16 files changed, 1393 insertions, 3107 deletions

diff --git a/drivers/lguest/Kconfig b/drivers/lguest/Kconfig
index 41e2250613a1..7eb9ecff8f4a 100644
--- a/drivers/lguest/Kconfig
+++ b/drivers/lguest/Kconfig
@@ -1,7 +1,6 @@
 config LGUEST
         tristate "Linux hypervisor example code"
-        depends on X86 && PARAVIRT && EXPERIMENTAL && !X86_PAE && FUTEX
-        select LGUEST_GUEST
+        depends on X86_32 && EXPERIMENTAL && !X86_PAE && FUTEX && !(X86_VISWS || X86_VOYAGER)
         select HVC_DRIVER
         ---help---
           This is a very simple module which allows you to run
@@ -18,13 +17,3 @@ config LGUEST_GUEST
           The guest needs code built-in, even if the host has lguest
           support as a module.  The drivers are tiny, so we build them
           in too.
-
-config LGUEST_NET
-        tristate
-        default y
-        depends on LGUEST_GUEST && NET
-
-config LGUEST_BLOCK
-        tristate
-        default y
-        depends on LGUEST_GUEST && BLOCK
diff --git a/drivers/lguest/Makefile b/drivers/lguest/Makefile
index e5047471c334..5e8272d296d8 100644
--- a/drivers/lguest/Makefile
+++ b/drivers/lguest/Makefile
@@ -1,10 +1,12 @@
-# Guest requires the paravirt_ops replacement and the bus driver.
-obj-$(CONFIG_LGUEST_GUEST) += lguest.o lguest_asm.o lguest_bus.o
+# Guest requires the device configuration and probing code.
+obj-$(CONFIG_LGUEST_GUEST) += lguest_device.o
 
 # Host requires the other files, which can be a module.
 obj-$(CONFIG_LGUEST)    += lg.o
-lg-y := core.o hypercalls.o page_tables.o interrupts_and_traps.o \
-        segments.o io.o lguest_user.o switcher.o
+lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
+        segments.o lguest_user.o
+
+lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o
 
 Preparation Preparation!: PREFIX=P
 Guest: PREFIX=G
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index a0788c12b392..35d19ae58de7 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -11,58 +11,20 @@
 #include <linux/vmalloc.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
+#include <linux/highmem.h>
 #include <asm/paravirt.h>
-#include <asm/desc.h>
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
 #include <asm/poll.h>
-#include <asm/highmem.h>
 #include <asm/asm-offsets.h>
-#include <asm/i387.h>
 #include "lg.h"
 
-/* Found in switcher.S */
-extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
-extern unsigned long default_idt_entries[];
-
-/* Every guest maps the core switcher code. */
-#define SHARED_SWITCHER_PAGES \
-        DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
-/* Pages for switcher itself, then two pages per cpu */
-#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * NR_CPUS)
-
-/* We map at -4M for ease of mapping into the guest (one PTE page). */
-#define SWITCHER_ADDR 0xFFC00000
 
 static struct vm_struct *switcher_vma;
 static struct page **switcher_page;
 
-static int cpu_had_pge;
-static struct {
-        unsigned long offset;
-        unsigned short segment;
-} lguest_entry;
-
 /* This One Big lock protects all inter-guest data structures. */
 DEFINE_MUTEX(lguest_lock);
-static DEFINE_PER_CPU(struct lguest *, last_guest);
-
-/* FIXME: Make dynamic. */
-#define MAX_LGUEST_GUESTS 16
-struct lguest lguests[MAX_LGUEST_GUESTS];
-
-/* Offset from where switcher.S was compiled to where we've copied it */
-static unsigned long switcher_offset(void)
-{
-        return SWITCHER_ADDR - (unsigned long)start_switcher_text;
-}
-
-/* This cpu's struct lguest_pages. */
-static struct lguest_pages *lguest_pages(unsigned int cpu)
-{
-        return &(((struct lguest_pages *)
-                  (SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
-}
 
 /*H:010 We need to set up the Switcher at a high virtual address.  Remember the
  * Switcher is a few hundred bytes of assembler code which actually changes the
@@ -73,9 +35,7 @@ static struct lguest_pages *lguest_pages(unsigned int cpu)
  * Host since it will be running as the switchover occurs.
  *
  * Trying to map memory at a particular address is an unusual thing to do, so
- * it's not a simple one-liner.  We also set up the per-cpu parts of the
- * Switcher here.
- */
+ * it's not a simple one-liner. */
 static __init int map_switcher(void)
 {
         int i, err;
@@ -132,90 +92,11 @@ static __init int map_switcher(void)
                 goto free_vma;
         }
 
-        /* Now the switcher is mapped at the right address, we can't fail!
-         * Copy in the compiled-in Switcher code (from switcher.S). */
+        /* Now the Switcher is mapped at the right address, we can't fail!
+         * Copy in the compiled-in Switcher code (from <arch>_switcher.S). */
         memcpy(switcher_vma->addr, start_switcher_text,
                end_switcher_text - start_switcher_text);
 
-        /* Most of the switcher.S doesn't care that it's been moved; on Intel,
-         * jumps are relative, and it doesn't access any references to external
-         * code or data.
-         *
-         * The only exception is the interrupt handlers in switcher.S: their
-         * addresses are placed in a table (default_idt_entries), so we need to
-         * update the table with the new addresses.  switcher_offset() is a
-         * convenience function which returns the distance between the builtin
-         * switcher code and the high-mapped copy we just made. */
-        for (i = 0; i < IDT_ENTRIES; i++)
-                default_idt_entries[i] += switcher_offset();
-
-        /*
-         * Set up the Switcher's per-cpu areas.
-         *
-         * Each CPU gets two pages of its own within the high-mapped region
-         * (aka. "struct lguest_pages").  Much of this can be initialized now,
-         * but some depends on what Guest we are running (which is set up in
-         * copy_in_guest_info()).
-         */
-        for_each_possible_cpu(i) {
-                /* lguest_pages() returns this CPU's two pages. */
-                struct lguest_pages *pages = lguest_pages(i);
-                /* This is a convenience pointer to make the code fit one
-                 * statement to a line. */
-                struct lguest_ro_state *state = &pages->state;
-
-                /* The Global Descriptor Table: the Host has a different one
-                 * for each CPU.  We keep a descriptor for the GDT which says
-                 * where it is and how big it is (the size is actually the last
-                 * byte, not the size, hence the "-1"). */
-                state->host_gdt_desc.size = GDT_SIZE-1;
-                state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
-
-                /* All CPUs on the Host use the same Interrupt Descriptor
-                 * Table, so we just use store_idt(), which gets this CPU's IDT
-                 * descriptor. */
-                store_idt(&state->host_idt_desc);
-
-                /* The descriptors for the Guest's GDT and IDT can be filled
-                 * out now, too.  We copy the GDT & IDT into ->guest_gdt and
-                 * ->guest_idt before actually running the Guest. */
-                state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
-                state->guest_idt_desc.address = (long)&state->guest_idt;
-                state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
-                state->guest_gdt_desc.address = (long)&state->guest_gdt;
-
-                /* We know where we want the stack to be when the Guest enters
-                 * the switcher: in pages->regs.  The stack grows upwards, so
-                 * we start it at the end of that structure. */
-                state->guest_tss.esp0 = (long)(&pages->regs + 1);
-                /* And this is the GDT entry to use for the stack: we keep a
-                 * couple of special LGUEST entries. */
-                state->guest_tss.ss0 = LGUEST_DS;
-
-                /* x86 can have a finegrained bitmap which indicates what I/O
-                 * ports the process can use.  We set it to the end of our
-                 * structure, meaning "none". */
-                state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
-
-                /* Some GDT entries are the same across all Guests, so we can
-                 * set them up now. */
-                setup_default_gdt_entries(state);
-                /* Most IDT entries are the same for all Guests, too.*/
-                setup_default_idt_entries(state, default_idt_entries);
-
-                /* The Host needs to be able to use the LGUEST segments on this
-                 * CPU, too, so put them in the Host GDT. */
-                get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
-                get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
-        }
-
-        /* In the Switcher, we want the %cs segment register to use the
-         * LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
-         * it will be undisturbed when we switch.  To change %cs and jump we
-         * need this structure to feed to Intel's "lcall" instruction. */
-        lguest_entry.offset = (long)switch_to_guest + switcher_offset();
-        lguest_entry.segment = LGUEST_CS;
-
         printk(KERN_INFO "lguest: mapped switcher at %p\n",
                switcher_vma->addr);
         /* And we succeeded... */
@@ -247,86 +128,12 @@ static void unmap_switcher(void)
                 __free_pages(switcher_page[i], 0);
 }
 
-/*H:130 Our Guest is usually so well behaved; it never tries to do things it
- * isn't allowed to.  Unfortunately, Linux's paravirtual infrastructure isn't
- * quite complete, because it doesn't contain replacements for the Intel I/O
- * instructions.  As a result, the Guest sometimes fumbles across one during
- * the boot process as it probes for various things which are usually attached
- * to a PC.
- *
- * When the Guest uses one of these instructions, we get trap #13 (General
- * Protection Fault) and come here.  We see if it's one of those troublesome
- * instructions and skip over it.  We return true if we did. */
-static int emulate_insn(struct lguest *lg)
-{
-        u8 insn;
-        unsigned int insnlen = 0, in = 0, shift = 0;
-        /* The eip contains the *virtual* address of the Guest's instruction:
-         * guest_pa just subtracts the Guest's page_offset. */
-        unsigned long physaddr = guest_pa(lg, lg->regs->eip);
-
-        /* The guest_pa() function only works for Guest kernel addresses, but
-         * that's all we're trying to do anyway. */
-        if (lg->regs->eip < lg->page_offset)
-                return 0;
-
-        /* Decoding x86 instructions is icky. */
-        lgread(lg, &insn, physaddr, 1);
-
-        /* 0x66 is an "operand prefix".  It means it's using the upper 16 bits
-           of the eax register. */
-        if (insn == 0x66) {
-                shift = 16;
-                /* The instruction is 1 byte so far, read the next byte. */
-                insnlen = 1;
-                lgread(lg, &insn, physaddr + insnlen, 1);
-        }
-
-        /* We can ignore the lower bit for the moment and decode the 4 opcodes
-         * we need to emulate. */
-        switch (insn & 0xFE) {
-        case 0xE4: /* in     <next byte>,%al */
-                insnlen += 2;
-                in = 1;
-                break;
-        case 0xEC: /* in     (%dx),%al */
-                insnlen += 1;
-                in = 1;
-                break;
-        case 0xE6: /* out    %al,<next byte> */
-                insnlen += 2;
-                break;
-        case 0xEE: /* out    %al,(%dx) */
-                insnlen += 1;
-                break;
-        default:
-                /* OK, we don't know what this is, can't emulate. */
-                return 0;
-        }
-
-        /* If it was an "IN" instruction, they expect the result to be read
-         * into %eax, so we change %eax.  We always return all-ones, which
-         * traditionally means "there's nothing there". */
-        if (in) {
-                /* Lower bit tells is whether it's a 16 or 32 bit access */
-                if (insn & 0x1)
-                        lg->regs->eax = 0xFFFFFFFF;
-                else
-                        lg->regs->eax |= (0xFFFF << shift);
-        }
-        /* Finally, we've "done" the instruction, so move past it. */
-        lg->regs->eip += insnlen;
-        /* Success! */
-        return 1;
-}
-/*:*/
-
 /*L:305
  * Dealing With Guest Memory.
  *
  * When the Guest gives us (what it thinks is) a physical address, we can use
- * the normal copy_from_user() & copy_to_user() on that address: remember,
- * Guest physical == Launcher virtual.
+ * the normal copy_from_user() & copy_to_user() on the corresponding place in
+ * the memory region allocated by the Launcher.
  *
  * But we can't trust the Guest: it might be trying to access the Launcher
  * code.  We have to check that the range is below the pfn_limit the Launcher
@@ -338,148 +145,27 @@ int lguest_address_ok(const struct lguest *lg,
         return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
 }
 
-/* This is a convenient routine to get a 32-bit value from the Guest (a very
- * common operation).  Here we can see how useful the kill_lguest() routine we
- * met in the Launcher can be: we return a random value (0) instead of needing
- * to return an error. */
-u32 lgread_u32(struct lguest *lg, unsigned long addr)
-{
-        u32 val = 0;
-
-        /* Don't let them access lguest binary. */
-        if (!lguest_address_ok(lg, addr, sizeof(val))
-            || get_user(val, (u32 __user *)addr) != 0)
-                kill_guest(lg, "bad read address %#lx", addr);
-        return val;
-}
-
-/* Same thing for writing a value. */
-void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val)
-{
-        if (!lguest_address_ok(lg, addr, sizeof(val))
-            || put_user(val, (u32 __user *)addr) != 0)
-                kill_guest(lg, "bad write address %#lx", addr);
-}
-
-/* This routine is more generic, and copies a range of Guest bytes into a
- * buffer.  If the copy_from_user() fails, we fill the buffer with zeroes, so
- * the caller doesn't end up using uninitialized kernel memory. */
-void lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
+/* This routine copies memory from the Guest.  Here we can see how useful the
+ * kill_lguest() routine we met in the Launcher can be: we return a random
+ * value (all zeroes) instead of needing to return an error. */
+void __lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes)
 {
         if (!lguest_address_ok(lg, addr, bytes)
-            || copy_from_user(b, (void __user *)addr, bytes) != 0) {
+            || copy_from_user(b, lg->mem_base + addr, bytes) != 0) {
                 /* copy_from_user should do this, but as we rely on it... */
                 memset(b, 0, bytes);
                 kill_guest(lg, "bad read address %#lx len %u", addr, bytes);
         }
 }
 
-/* Similarly, our generic routine to copy into a range of Guest bytes. */
-void lgwrite(struct lguest *lg, unsigned long addr, const void *b,
-             unsigned bytes)
+/* This is the write (copy into guest) version. */
+void __lgwrite(struct lguest *lg, unsigned long addr, const void *b,
+               unsigned bytes)
 {
         if (!lguest_address_ok(lg, addr, bytes)
-            || copy_to_user((void __user *)addr, b, bytes) != 0)
+            || copy_to_user(lg->mem_base + addr, b, bytes) != 0)
                 kill_guest(lg, "bad write address %#lx len %u", addr, bytes);
 }
-/* (end of memory access helper routines) :*/
-
-static void set_ts(void)
-{
-        u32 cr0;
-
-        cr0 = read_cr0();
-        if (!(cr0 & 8))
-                write_cr0(cr0|8);
-}
-
-/*S:010
- * We are getting close to the Switcher.
- *
- * Remember that each CPU has two pages which are visible to the Guest when it
- * runs on that CPU.  This has to contain the state for that Guest: we copy the
- * state in just before we run the Guest.
- *
- * Each Guest has "changed" flags which indicate what has changed in the Guest
- * since it last ran.  We saw this set in interrupts_and_traps.c and
- * segments.c.
- */
-static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
-{
-        /* Copying all this data can be quite expensive.  We usually run the
-         * same Guest we ran last time (and that Guest hasn't run anywhere else
-         * meanwhile).  If that's not the case, we pretend everything in the
-         * Guest has changed. */
-        if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
-                __get_cpu_var(last_guest) = lg;
-                lg->last_pages = pages;
-                lg->changed = CHANGED_ALL;
-        }
-
-        /* These copies are pretty cheap, so we do them unconditionally: */
-        /* Save the current Host top-level page directory. */
-        pages->state.host_cr3 = __pa(current->mm->pgd);
-        /* Set up the Guest's page tables to see this CPU's pages (and no
-         * other CPU's pages). */
-        map_switcher_in_guest(lg, pages);
-        /* Set up the two "TSS" members which tell the CPU what stack to use
-         * for traps which do directly into the Guest (ie. traps at privilege
-         * level 1). */
-        pages->state.guest_tss.esp1 = lg->esp1;
-        pages->state.guest_tss.ss1 = lg->ss1;
-
-        /* Copy direct-to-Guest trap entries. */
-        if (lg->changed & CHANGED_IDT)
-                copy_traps(lg, pages->state.guest_idt, default_idt_entries);
-
-        /* Copy all GDT entries which the Guest can change. */
-        if (lg->changed & CHANGED_GDT)
-                copy_gdt(lg, pages->state.guest_gdt);
-        /* If only the TLS entries have changed, copy them. */
-        else if (lg->changed & CHANGED_GDT_TLS)
-                copy_gdt_tls(lg, pages->state.guest_gdt);
-
-        /* Mark the Guest as unchanged for next time. */
-        lg->changed = 0;
-}
-
-/* Finally: the code to actually call into the Switcher to run the Guest. */
-static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
-{
-        /* This is a dummy value we need for GCC's sake. */
-        unsigned int clobber;
-
-        /* Copy the guest-specific information into this CPU's "struct
-         * lguest_pages". */
-        copy_in_guest_info(lg, pages);
-
-        /* Set the trap number to 256 (impossible value).  If we fault while
-         * switching to the Guest (bad segment registers or bug), this will
-         * cause us to abort the Guest. */
-        lg->regs->trapnum = 256;
-
-        /* Now: we push the "eflags" register on the stack, then do an "lcall".
-         * This is how we change from using the kernel code segment to using
-         * the dedicated lguest code segment, as well as jumping into the
-         * Switcher.
-         *
-         * The lcall also pushes the old code segment (KERNEL_CS) onto the
-         * stack, then the address of this call.  This stack layout happens to
-         * exactly match the stack of an interrupt... */
-        asm volatile("pushf; lcall *lguest_entry"
-                     /* This is how we tell GCC that %eax ("a") and %ebx ("b")
-                      * are changed by this routine.  The "=" means output. */
-                     : "=a"(clobber), "=b"(clobber)
-                     /* %eax contains the pages pointer.  ("0" refers to the
-                      * 0-th argument above, ie "a").  %ebx contains the
-                      * physical address of the Guest's top-level page
-                      * directory. */
-                     : "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
-                     /* We tell gcc that all these registers could change,
-                      * which means we don't have to save and restore them in
-                      * the Switcher. */
-                     : "memory", "%edx", "%ecx", "%edi", "%esi");
-}
 /*:*/
 
 /*H:030 Let's jump straight to the the main loop which runs the Guest.
@@ -489,22 +175,16 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
 {
         /* We stop running once the Guest is dead. */
         while (!lg->dead) {
-                /* We need to initialize this, otherwise gcc complains.  It's
-                 * not (yet) clever enough to see that it's initialized when we
-                 * need it. */
-                unsigned int cr2 = 0; /* Damn gcc */
-
-                /* First we run any hypercalls the Guest wants done: either in
-                 * the hypercall ring in "struct lguest_data", or directly by
-                 * using int 31 (LGUEST_TRAP_ENTRY). */
-                do_hypercalls(lg);
-                /* It's possible the Guest did a SEND_DMA hypercall to the
+                /* First we run any hypercalls the Guest wants done. */
+                if (lg->hcall)
+                        do_hypercalls(lg);
+
+                /* It's possible the Guest did a NOTIFY hypercall to the
                  * Launcher, in which case we return from the read() now. */
-                if (lg->dma_is_pending) {
-                        if (put_user(lg->pending_dma, user) ||
-                            put_user(lg->pending_key, user+1))
+                if (lg->pending_notify) {
+                        if (put_user(lg->pending_notify, user))
                                 return -EFAULT;
-                        return sizeof(unsigned long)*2;
+                        return sizeof(lg->pending_notify);
                 }
 
                 /* Check for signals */
@@ -542,144 +222,20 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
                  * the "Do Not Disturb" sign: */
                 local_irq_disable();
 
-                /* Remember the awfully-named TS bit?  If the Guest has asked
-                 * to set it we set it now, so we can trap and pass that trap
-                 * to the Guest if it uses the FPU. */
-                if (lg->ts)
-                        set_ts();
-
-                /* SYSENTER is an optimized way of doing system calls.  We
-                 * can't allow it because it always jumps to privilege level 0.
-                 * A normal Guest won't try it because we don't advertise it in
-                 * CPUID, but a malicious Guest (or malicious Guest userspace
-                 * program) could, so we tell the CPU to disable it before
-                 * running the Guest. */
-                if (boot_cpu_has(X86_FEATURE_SEP))
-                        wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
-
-                /* Now we actually run the Guest.  It will pop back out when
-                 * something interesting happens, and we can examine its
-                 * registers to see what it was doing. */
-                run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
-
-                /* The "regs" pointer contains two extra entries which are not
-                 * really registers: a trap number which says what interrupt or
-                 * trap made the switcher code come back, and an error code
-                 * which some traps set.  */
-
-                /* If the Guest page faulted, then the cr2 register will tell
-                 * us the bad virtual address.  We have to grab this now,
-                 * because once we re-enable interrupts an interrupt could
-                 * fault and thus overwrite cr2, or we could even move off to a
-                 * different CPU. */
-                if (lg->regs->trapnum == 14)
-                        cr2 = read_cr2();
-                /* Similarly, if we took a trap because the Guest used the FPU,
-                 * we have to restore the FPU it expects to see. */
-                else if (lg->regs->trapnum == 7)
-                        math_state_restore();
-
-                /* Restore SYSENTER if it's supposed to be on. */
-                if (boot_cpu_has(X86_FEATURE_SEP))
-                        wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
+                /* Actually run the Guest until something happens. */
+                lguest_arch_run_guest(lg);
 
                 /* Now we're ready to be interrupted or moved to other CPUs */
                 local_irq_enable();
 
-                /* OK, so what happened? */
-                switch (lg->regs->trapnum) {
-                case 13: /* We've intercepted a GPF. */
-                        /* Check if this was one of those annoying IN or OUT
-                         * instructions which we need to emulate.  If so, we
-                         * just go back into the Guest after we've done it. */
-                        if (lg->regs->errcode == 0) {
-                                if (emulate_insn(lg))
-                                        continue;
-                        }
-                        break;
-                case 14: /* We've intercepted a page fault. */
-                        /* The Guest accessed a virtual address that wasn't
-                         * mapped.  This happens a lot: we don't actually set
-                         * up most of the page tables for the Guest at all when
-                         * we start: as it runs it asks for more and more, and
-                         * we set them up as required. In this case, we don't
-                         * even tell the Guest that the fault happened.
-                         *
-                         * The errcode tells whether this was a read or a
-                         * write, and whether kernel or userspace code. */
-                        if (demand_page(lg, cr2, lg->regs->errcode))
-                                continue;
-
-                        /* OK, it's really not there (or not OK): the Guest
-                         * needs to know.  We write out the cr2 value so it
-                         * knows where the fault occurred.
-                         *
-                         * Note that if the Guest were really messed up, this
-                         * could happen before it's done the INITIALIZE
-                         * hypercall, so lg->lguest_data will be NULL, so
-                         * &lg->lguest_data->cr2 will be address 8.  Writing
-                         * into that address won't hurt the Host at all,
-                         * though. */
-                        if (put_user(cr2, &lg->lguest_data->cr2))
-                                kill_guest(lg, "Writing cr2");
-                        break;
-                case 7: /* We've intercepted a Device Not Available fault. */
-                        /* If the Guest doesn't want to know, we already
-                         * restored the Floating Point Unit, so we just
-                         * continue without telling it. */
-                        if (!lg->ts)
-                                continue;
-                        break;
-                case 32 ... 255:
-                        /* These values mean a real interrupt occurred, in
-                         * which case the Host handler has already been run.
-                         * We just do a friendly check if another process
-                         * should now be run, then fall through to loop
-                         * around: */
-                        cond_resched();
-                case LGUEST_TRAP_ENTRY: /* Handled at top of loop */
-                        continue;
-                }
-
-                /* If we get here, it's a trap the Guest wants to know
-                 * about. */
-                if (deliver_trap(lg, lg->regs->trapnum))
-                        continue;
-
-                /* If the Guest doesn't have a handler (either it hasn't
-                 * registered any yet, or it's one of the faults we don't let
-                 * it handle), it dies with a cryptic error message. */
-                kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
-                           lg->regs->trapnum, lg->regs->eip,
-                           lg->regs->trapnum == 14 ? cr2 : lg->regs->errcode);
+                /* Now we deal with whatever happened to the Guest. */
+                lguest_arch_handle_trap(lg);
         }
+
         /* The Guest is dead => "No such file or directory" */
         return -ENOENT;
 }
 
-/* Now we can look at each of the routines this calls, in increasing order of
- * complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
- * deliver_trap() and demand_page().  After all those, we'll be ready to
- * examine the Switcher, and our philosophical understanding of the Host/Guest
- * duality will be complete. :*/
-
-int find_free_guest(void)
-{
-        unsigned int i;
-        for (i = 0; i < MAX_LGUEST_GUESTS; i++)
-                if (!lguests[i].tsk)
-                        return i;
-        return -1;
-}
-
-static void adjust_pge(void *on)
-{
-        if (on)
-                write_cr4(read_cr4() | X86_CR4_PGE);
-        else
-                write_cr4(read_cr4() & ~X86_CR4_PGE);
-}
-
 /*H:000
  * Welcome to the Host!
  *
@@ -701,72 +257,50 @@ static int __init init(void)
         /* First we put the Switcher up in very high virtual memory. */
         err = map_switcher();
         if (err)
-                return err;
+                goto out;
 
         /* Now we set up the pagetable implementation for the Guests. */
         err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
-        if (err) {
-                unmap_switcher();
-                return err;
-        }
+        if (err)
+                goto unmap;
 
-        /* The I/O subsystem needs some things initialized. */
-        lguest_io_init();
+        /* We might need to reserve an interrupt vector. */
+        err = init_interrupts();
+        if (err)
+                goto free_pgtables;
 
         /* /dev/lguest needs to be registered. */
         err = lguest_device_init();
-        if (err) {
-                free_pagetables();
-                unmap_switcher();
-                return err;
-        }
+        if (err)
+                goto free_interrupts;
 
-        /* Finally, we need to turn off "Page Global Enable".  PGE is an
-         * optimization where page table entries are specially marked to show
-         * they never change.  The Host kernel marks all the kernel pages this
-         * way because it's always present, even when userspace is running.
-         *
-         * Lguest breaks this: unbeknownst to the rest of the Host kernel, we
-         * switch to the Guest kernel.  If you don't disable this on all CPUs,
-         * you'll get really weird bugs that you'll chase for two days.
-         *
-         * I used to turn PGE off every time we switched to the Guest and back
-         * on when we return, but that slowed the Switcher down noticibly. */
-
-        /* We don't need the complexity of CPUs coming and going while we're
-         * doing this. */
-        lock_cpu_hotplug();
-        if (cpu_has_pge) { /* We have a broader idea of "global". */
-                /* Remember that this was originally set (for cleanup). */
-                cpu_had_pge = 1;
-                /* adjust_pge is a helper function which sets or unsets the PGE
-                 * bit on its CPU, depending on the argument (0 == unset). */
-                on_each_cpu(adjust_pge, (void *)0, 0, 1);
-                /* Turn off the feature in the global feature set. */
-                clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
-        }
-        unlock_cpu_hotplug();
+        /* Finally we do some architecture-specific setup. */
+        lguest_arch_host_init();
 
         /* All good! */
         return 0;
+
+free_interrupts:
+        free_interrupts();
+free_pgtables:
+        free_pagetables();
+unmap:
+        unmap_switcher();
+out:
+        return err;
 }
 
 /* Cleaning up is just the same code, backwards.  With a little French. */
 static void __exit fini(void)
 {
         lguest_device_remove();
+        free_interrupts();
         free_pagetables();
         unmap_switcher();
 
-        /* If we had PGE before we started, turn it back on now. */
-        lock_cpu_hotplug();
-        if (cpu_had_pge) {
-                set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
-                /* adjust_pge's argument "1" means set PGE. */
-                on_each_cpu(adjust_pge, (void *)1, 0, 1);
-        }
-        unlock_cpu_hotplug();
+        lguest_arch_host_fini();
 }
+/*:*/
 
 /* The Host side of lguest can be a module.  This is a nice way for people to
  * play with it.  */
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index db6caace3b9c..9d5184c7c14a 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -25,17 +25,13 @@
 #include <linux/mm.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
-#include <irq_vectors.h>
 #include "lg.h"
 
-/*H:120 This is the core hypercall routine: where the Guest gets what it
- * wants.  Or gets killed.  Or, in the case of LHCALL_CRASH, both.
- *
- * Remember from the Guest: %eax == which call to make, and the arguments are
- * packed into %edx, %ebx and %ecx if needed. */
-static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
+/*H:120 This is the core hypercall routine: where the Guest gets what it wants.
+ * Or gets killed.  Or, in the case of LHCALL_CRASH, both. */
+static void do_hcall(struct lguest *lg, struct hcall_args *args)
 {
-        switch (regs->eax) {
+        switch (args->arg0) {
         case LHCALL_FLUSH_ASYNC:
                 /* This call does nothing, except by breaking out of the Guest
                  * it makes us process all the asynchronous hypercalls. */
@@ -51,7 +47,7 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
                 char msg[128];
                 /* If the lgread fails, it will call kill_guest() itself; the
                  * kill_guest() with the message will be ignored. */
-                lgread(lg, msg, regs->edx, sizeof(msg));
+                __lgread(lg, msg, args->arg1, sizeof(msg));
                 msg[sizeof(msg)-1] = '\0';
                 kill_guest(lg, "CRASH: %s", msg);
                 break;
@@ -59,67 +55,49 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
         case LHCALL_FLUSH_TLB:
                 /* FLUSH_TLB comes in two flavors, depending on the
                  * argument: */
-                if (regs->edx)
+                if (args->arg1)
                         guest_pagetable_clear_all(lg);
                 else
                         guest_pagetable_flush_user(lg);
                 break;
-        case LHCALL_BIND_DMA:
-                /* BIND_DMA really wants four arguments, but it's the only call
-                 * which does.  So the Guest packs the number of buffers and
-                 * the interrupt number into the final argument, and we decode
-                 * it here.  This can legitimately fail, since we currently
-                 * place a limit on the number of DMA pools a Guest can have.
-                 * So we return true or false from this call. */
-                regs->eax = bind_dma(lg, regs->edx, regs->ebx,
-                                     regs->ecx >> 8, regs->ecx & 0xFF);
-                break;
 
         /* All these calls simply pass the arguments through to the right
          * routines. */
-        case LHCALL_SEND_DMA:
-                send_dma(lg, regs->edx, regs->ebx);
-                break;
-        case LHCALL_LOAD_GDT:
-                load_guest_gdt(lg, regs->edx, regs->ebx);
-                break;
-        case LHCALL_LOAD_IDT_ENTRY:
-                load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
-                break;
         case LHCALL_NEW_PGTABLE:
-                guest_new_pagetable(lg, regs->edx);
+                guest_new_pagetable(lg, args->arg1);
                 break;
         case LHCALL_SET_STACK:
-                guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
+                guest_set_stack(lg, args->arg1, args->arg2, args->arg3);
                 break;
         case LHCALL_SET_PTE:
-                guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
+                guest_set_pte(lg, args->arg1, args->arg2, __pte(args->arg3));
                 break;
         case LHCALL_SET_PMD:
-                guest_set_pmd(lg, regs->edx, regs->ebx);
-                break;
-        case LHCALL_LOAD_TLS:
-                guest_load_tls(lg, regs->edx);
+                guest_set_pmd(lg, args->arg1, args->arg2);
                 break;
         case LHCALL_SET_CLOCKEVENT:
-                guest_set_clockevent(lg, regs->edx);
+                guest_set_clockevent(lg, args->arg1);
                 break;
-
         case LHCALL_TS:
                 /* This sets the TS flag, as we saw used in run_guest(). */
-                lg->ts = regs->edx;
+                lg->ts = args->arg1;
                 break;
         case LHCALL_HALT:
                 /* Similarly, this sets the halted flag for run_guest(). */
                 lg->halted = 1;
                 break;
+        case LHCALL_NOTIFY:
+                lg->pending_notify = args->arg1;
+                break;
         default:
-                kill_guest(lg, "Bad hypercall %li\n", regs->eax);
+                if (lguest_arch_do_hcall(lg, args))
+                        kill_guest(lg, "Bad hypercall %li\n", args->arg0);
         }
 }
+/*:*/
 
-/* Asynchronous hypercalls are easy: we just look in the array in the Guest's
- * "struct lguest_data" and see if there are any new ones marked "ready".
+/*H:124 Asynchronous hypercalls are easy: we just look in the array in the
+ * Guest's "struct lguest_data" to see if any new ones are marked "ready".
  *
  * We are careful to do these in order: obviously we respect the order the
  * Guest put them in the ring, but we also promise the Guest that they will
@@ -134,10 +112,9 @@ static void do_async_hcalls(struct lguest *lg)
         if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
                 return;
 
-
         /* We process "struct lguest_data"s hcalls[] ring once. */
         for (i = 0; i < ARRAY_SIZE(st); i++) {
-                struct lguest_regs regs;
+                struct hcall_args args;
                 /* We remember where we were up to from last time.  This makes
                  * sure that the hypercalls are done in the order the Guest
                  * places them in the ring. */
@@ -152,18 +129,16 @@ static void do_async_hcalls(struct lguest *lg)
                 if (++lg->next_hcall == LHCALL_RING_SIZE)
                         lg->next_hcall = 0;
 
-                /* We copy the hypercall arguments into a fake register
-                 * structure.  This makes life simple for do_hcall(). */
-                if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax)
-                    || get_user(regs.edx, &lg->lguest_data->hcalls[n].edx)
-                    || get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx)
-                    || get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) {
+                /* Copy the hypercall arguments into a local copy of
+                 * the hcall_args struct. */
+                if (copy_from_user(&args, &lg->lguest_data->hcalls[n],
+                                   sizeof(struct hcall_args))) {
                         kill_guest(lg, "Fetching async hypercalls");
                         break;
                 }
 
                 /* Do the hypercall, same as a normal one. */
-                do_hcall(lg, &regs);
+                do_hcall(lg, &args);
 
                 /* Mark the hypercall done. */
                 if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
@@ -171,9 +146,9 @@ static void do_async_hcalls(struct lguest *lg)
                         break;
                 }
 
-                /* Stop doing hypercalls if we've just done a DMA to the
-                 * Launcher: it needs to service this first. */
-                if (lg->dma_is_pending)
+                /* Stop doing hypercalls if they want to notify the Launcher:
+                 * it needs to service this first. */
+                if (lg->pending_notify)
                         break;
         }
 }
@@ -182,76 +157,35 @@ static void do_async_hcalls(struct lguest *lg)
  * Guest makes a hypercall, we end up here to set things up: */
 static void initialize(struct lguest *lg)
 {
-        u32 tsc_speed;
 
         /* You can't do anything until you're initialized.  The Guest knows the
          * rules, so we're unforgiving here. */
-        if (lg->regs->eax != LHCALL_LGUEST_INIT) {
-                kill_guest(lg, "hypercall %li before LGUEST_INIT",
-                           lg->regs->eax);
+        if (lg->hcall->arg0 != LHCALL_LGUEST_INIT) {
+                kill_guest(lg, "hypercall %li before INIT", lg->hcall->arg0);
                 return;
         }
 
-        /* We insist that the Time Stamp Counter exist and doesn't change with
-         * cpu frequency.  Some devious chip manufacturers decided that TSC
-         * changes could be handled in software.  I decided that time going
-         * backwards might be good for benchmarks, but it's bad for users.
-         *
-         * We also insist that the TSC be stable: the kernel detects unreliable
-         * TSCs for its own purposes, and we use that here. */
-        if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
-                tsc_speed = tsc_khz;
-        else
-                tsc_speed = 0;
-
-        /* The pointer to the Guest's "struct lguest_data" is the only
-         * argument. */
-        lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
-        /* If we check the address they gave is OK now, we can simply
-         * copy_to_user/from_user from now on rather than using lgread/lgwrite.
-         * I put this in to show that I'm not immune to writing stupid
-         * optimizations. */
-        if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
+        if (lguest_arch_init_hypercalls(lg))
                 kill_guest(lg, "bad guest page %p", lg->lguest_data);
-                return;
-        }
+
         /* The Guest tells us where we're not to deliver interrupts by putting
          * the range of addresses into "struct lguest_data". */
         if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
-            || get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
-            /* We tell the Guest that it can't use the top 4MB of virtual
-             * addresses used by the Switcher. */
-            || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
-            || put_user(tsc_speed, &lg->lguest_data->tsc_khz)
-            /* We also give the Guest a unique id, as used in lguest_net.c. */
-            || put_user(lg->guestid, &lg->lguest_data->guestid))
+            || get_user(lg->noirq_end, &lg->lguest_data->noirq_end))
                 kill_guest(lg, "bad guest page %p", lg->lguest_data);
 
         /* We write the current time into the Guest's data page once now. */
         write_timestamp(lg);
 
+        /* page_tables.c will also do some setup. */
+        page_table_guest_data_init(lg);
+
         /* This is the one case where the above accesses might have been the
          * first write to a Guest page.  This may have caused a copy-on-write
          * fault, but the Guest might be referring to the old (read-only)
          * page. */
         guest_pagetable_clear_all(lg);
 }
-/* Now we've examined the hypercall code; our Guest can make requests.  There
- * is one other way we can do things for the Guest, as we see in
- * emulate_insn(). */
-
-/*H:110 Tricky point: we mark the hypercall as "done" once we've done it.
- * Normally we don't need to do this: the Guest will run again and update the
- * trap number before we come back around the run_guest() loop to
- * do_hypercalls().
- *
- * However, if we are signalled or the Guest sends DMA to the Launcher, that
- * loop will exit without running the Guest.  When it comes back it would try
- * to re-run the hypercall. */
-static void clear_hcall(struct lguest *lg)
-{
-        lg->regs->trapnum = 255;
-}
 
 /*H:100
  * Hypercalls
@@ -261,16 +195,12 @@ static void clear_hcall(struct lguest *lg)
  */
 void do_hypercalls(struct lguest *lg)
 {
-        /* Not initialized yet? */
+        /* Not initialized yet?  This hypercall must do it. */
         if (unlikely(!lg->lguest_data)) {
-                /* Did the Guest make a hypercall?  We might have come back for
-                 * some other reason (an interrupt, a different trap). */
-                if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
-                        /* Set up the "struct lguest_data" */
-                        initialize(lg);
-                        /* The hypercall is done. */
-                        clear_hcall(lg);
-                }
+                /* Set up the "struct lguest_data" */
+                initialize(lg);
+                /* Hcall is done. */
+                lg->hcall = NULL;
                 return;
         }
 
@@ -280,12 +210,21 @@ void do_hypercalls(struct lguest *lg)
         do_async_hcalls(lg);
 
         /* If we stopped reading the hypercall ring because the Guest did a
-         * SEND_DMA to the Launcher, we want to return now.  Otherwise if the
-         * Guest asked us to do a hypercall, we do it. */
-        if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
-                do_hcall(lg, lg->regs);
-                /* The hypercall is done. */
-                clear_hcall(lg);
+         * NOTIFY to the Launcher, we want to return now.  Otherwise we do
+         * the hypercall. */
+        if (!lg->pending_notify) {
+                do_hcall(lg, lg->hcall);
+                /* Tricky point: we reset the hcall pointer to mark the
+                 * hypercall as "done".  We use the hcall pointer rather than
+                 * the trap number to indicate a hypercall is pending.
+                 * Normally it doesn't matter: the Guest will run again and
+                 * update the trap number before we come back here.
+                 *
+                 * However, if we are signalled or the Guest sends DMA to the
+                 * Launcher, the run_guest() loop will exit without running the
+                 * Guest.  When it comes back it would try to re-run the
+                 * hypercall. */
+                lg->hcall = NULL;
         }
 }
 
@@ -295,6 +234,6 @@ void write_timestamp(struct lguest *lg)
 {
         struct timespec now;
         ktime_get_real_ts(&now);
-        if (put_user(now, &lg->lguest_data->time))
+        if (copy_to_user(&lg->lguest_data->time, &now, sizeof(struct timespec)))
                 kill_guest(lg, "Writing timestamp");
 }
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 39731232d827..82966982cb38 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -12,8 +12,14 @@
  * them first, so we also have a way of "reflecting" them into the Guest as if
  * they had been delivered to it directly. :*/
 #include <linux/uaccess.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
 #include "lg.h"
 
+/* Allow Guests to use a non-128 (ie. non-Linux) syscall trap. */
+static unsigned int syscall_vector = SYSCALL_VECTOR;
+module_param(syscall_vector, uint, 0444);
+
 /* The address of the interrupt handler is split into two bits: */
 static unsigned long idt_address(u32 lo, u32 hi)
 {
@@ -39,7 +45,7 @@ static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val)
 {
         /* Stack grows upwards: move stack then write value. */
         *gstack -= 4;
-        lgwrite_u32(lg, *gstack, val);
+        lgwrite(lg, *gstack, u32, val);
 }
 
 /*H:210 The set_guest_interrupt() routine actually delivers the interrupt or
@@ -56,8 +62,9 @@ static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val)
  * it). */
 static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
 {
-        unsigned long gstack;
+        unsigned long gstack, origstack;
         u32 eflags, ss, irq_enable;
+        unsigned long virtstack;
 
         /* There are two cases for interrupts: one where the Guest is already
          * in the kernel, and a more complex one where the Guest is in
@@ -65,8 +72,10 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
         if ((lg->regs->ss&0x3) != GUEST_PL) {
                 /* The Guest told us their kernel stack with the SET_STACK
                  * hypercall: both the virtual address and the segment */
-                gstack = guest_pa(lg, lg->esp1);
+                virtstack = lg->esp1;
                 ss = lg->ss1;
+
+                origstack = gstack = guest_pa(lg, virtstack);
                 /* We push the old stack segment and pointer onto the new
                  * stack: when the Guest does an "iret" back from the interrupt
                  * handler the CPU will notice they're dropping privilege
@@ -75,8 +84,10 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
                 push_guest_stack(lg, &gstack, lg->regs->esp);
         } else {
                 /* We're staying on the same Guest (kernel) stack. */
-                gstack = guest_pa(lg, lg->regs->esp);
+                virtstack = lg->regs->esp;
                 ss = lg->regs->ss;
+
+                origstack = gstack = guest_pa(lg, virtstack);
         }
 
         /* Remember that we never let the Guest actually disable interrupts, so
@@ -102,7 +113,7 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
         /* Now we've pushed all the old state, we change the stack, the code
          * segment and the address to execute. */
         lg->regs->ss = ss;
-        lg->regs->esp = gstack + lg->page_offset;
+        lg->regs->esp = virtstack + (gstack - origstack);
         lg->regs->cs = (__KERNEL_CS|GUEST_PL);
         lg->regs->eip = idt_address(lo, hi);
 
@@ -165,7 +176,7 @@ void maybe_do_interrupt(struct lguest *lg)
         /* Look at the IDT entry the Guest gave us for this interrupt.  The
          * first 32 (FIRST_EXTERNAL_VECTOR) entries are for traps, so we skip
          * over them. */
-        idt = &lg->idt[FIRST_EXTERNAL_VECTOR+irq];
+        idt = &lg->arch.idt[FIRST_EXTERNAL_VECTOR+irq];
         /* If they don't have a handler (yet?), we just ignore it */
         if (idt_present(idt->a, idt->b)) {
                 /* OK, mark it no longer pending and deliver it. */
@@ -183,6 +194,47 @@ void maybe_do_interrupt(struct lguest *lg)
          * timer interrupt. */
         write_timestamp(lg);
 }
+/*:*/
+
+/* Linux uses trap 128 for system calls.  Plan9 uses 64, and Ron Minnich sent
+ * me a patch, so we support that too.  It'd be a big step for lguest if half
+ * the Plan 9 user base were to start using it.
+ *
+ * Actually now I think of it, it's possible that Ron *is* half the Plan 9
+ * userbase.  Oh well. */
+static bool could_be_syscall(unsigned int num)
+{
+        /* Normal Linux SYSCALL_VECTOR or reserved vector? */
+        return num == SYSCALL_VECTOR || num == syscall_vector;
+}
+
+/* The syscall vector it wants must be unused by Host. */
+bool check_syscall_vector(struct lguest *lg)
+{
+        u32 vector;
+
+        if (get_user(vector, &lg->lguest_data->syscall_vec))
+                return false;
+
+        return could_be_syscall(vector);
+}
+
+int init_interrupts(void)
+{
+        /* If they want some strange system call vector, reserve it now */
+        if (syscall_vector != SYSCALL_VECTOR
+            && test_and_set_bit(syscall_vector, used_vectors)) {
+                printk("lg: couldn't reserve syscall %u\n", syscall_vector);
+                return -EBUSY;
+        }
+        return 0;
+}
+
+void free_interrupts(void)
+{
+        if (syscall_vector != SYSCALL_VECTOR)
+                clear_bit(syscall_vector, used_vectors);
+}
 
 /*H:220 Now we've got the routines to deliver interrupts, delivering traps
  * like page fault is easy.  The only trick is that Intel decided that some
@@ -197,14 +249,14 @@ int deliver_trap(struct lguest *lg, unsigned int num)
 {
         /* Trap numbers are always 8 bit, but we set an impossible trap number
          * for traps inside the Switcher, so check that here. */
-        if (num >= ARRAY_SIZE(lg->idt))
+        if (num >= ARRAY_SIZE(lg->arch.idt))
                 return 0;
 
         /* Early on the Guest hasn't set the IDT entries (or maybe it put a
          * bogus one in): if we fail here, the Guest will be killed. */
-        if (!idt_present(lg->idt[num].a, lg->idt[num].b))
+        if (!idt_present(lg->arch.idt[num].a, lg->arch.idt[num].b))
                 return 0;
-        set_guest_interrupt(lg, lg->idt[num].a, lg->idt[num].b, has_err(num));
+        set_guest_interrupt(lg, lg->arch.idt[num].a, lg->arch.idt[num].b, has_err(num));
         return 1;
 }
 
@@ -218,28 +270,20 @@ int deliver_trap(struct lguest *lg, unsigned int num)
  * system calls down from 1750ns to 270ns.  Plus, if lguest didn't do it, all
  * the other hypervisors would tease it.
  *
- * This routine determines if a trap can be delivered directly. */
-static int direct_trap(const struct lguest *lg,
-                       const struct desc_struct *trap,
-                       unsigned int num)
+ * This routine indicates if a particular trap number could be delivered
+ * directly. */
+static int direct_trap(unsigned int num)
 {
         /* Hardware interrupts don't go to the Guest at all (except system
          * call). */
-        if (num >= FIRST_EXTERNAL_VECTOR && num != SYSCALL_VECTOR)
+        if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num))
                 return 0;
 
         /* The Host needs to see page faults (for shadow paging and to save the
          * fault address), general protection faults (in/out emulation) and
          * device not available (TS handling), and of course, the hypercall
          * trap. */
-        if (num == 14 || num == 13 || num == 7 || num == LGUEST_TRAP_ENTRY)
-                return 0;
-
-        /* Only trap gates (type 15) can go direct to the Guest.  Interrupt
-         * gates (type 14) disable interrupts as they are entered, which we
-         * never let the Guest do.  Not present entries (type 0x0) also can't
-         * go direct, of course 8) */
-        return idt_type(trap->a, trap->b) == 0xF;
+        return num != 14 && num != 13 && num != 7 && num != LGUEST_TRAP_ENTRY;
 }
 /*:*/
 
@@ -348,15 +392,11 @@ void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi)
          * to copy this again. */
         lg->changed |= CHANGED_IDT;
 
-        /* The IDT which we keep in "struct lguest" only contains 32 entries
-         * for the traps and LGUEST_IRQS (32) entries for interrupts.  We
-         * ignore attempts to set handlers for higher interrupt numbers, except
-         * for the system call "interrupt" at 128: we have a special IDT entry
-         * for that. */
-        if (num < ARRAY_SIZE(lg->idt))
-                set_trap(lg, &lg->idt[num], num, lo, hi);
-        else if (num == SYSCALL_VECTOR)
-                set_trap(lg, &lg->syscall_idt, num, lo, hi);
+        /* Check that the Guest doesn't try to step outside the bounds. */
+        if (num >= ARRAY_SIZE(lg->arch.idt))
+                kill_guest(lg, "Setting idt entry %u", num);
+        else
+                set_trap(lg, &lg->arch.idt[num], num, lo, hi);
 }
 
 /* The default entry for each interrupt points into the Switcher routines which
@@ -399,20 +439,21 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
 
         /* We can simply copy the direct traps, otherwise we use the default
          * ones in the Switcher: they will return to the Host. */
-        for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) {
-                if (direct_trap(lg, &lg->idt[i], i))
-                        idt[i] = lg->idt[i];
+        for (i = 0; i < ARRAY_SIZE(lg->arch.idt); i++) {
+                /* If no Guest can ever override this trap, leave it alone. */
+                if (!direct_trap(i))
+                        continue;
+
+                /* Only trap gates (type 15) can go direct to the Guest.
+                 * Interrupt gates (type 14) disable interrupts as they are
+                 * entered, which we never let the Guest do.  Not present
+                 * entries (type 0x0) also can't go direct, of course. */
+                if (idt_type(lg->arch.idt[i].a, lg->arch.idt[i].b) == 0xF)
+                        idt[i] = lg->arch.idt[i];
                 else
+                        /* Reset it to the default. */
                         default_idt_entry(&idt[i], i, def[i]);
         }
-
-        /* Don't forget the system call trap!  The IDT entries for other
-         * interupts never change, so no need to copy them. */
-        i = SYSCALL_VECTOR;
-        if (direct_trap(lg, &lg->syscall_idt, i))
-                idt[i] = lg->syscall_idt;
-        else
-                default_idt_entry(&idt[i], i, def[i]);
 }
 
 void guest_set_clockevent(struct lguest *lg, unsigned long delta)
diff --git a/drivers/lguest/io.c b/drivers/lguest/io.c
deleted file mode 100644
index ea68613b43f6..000000000000
--- a/drivers/lguest/io.c
+++ /dev/null
@@ -1,626 +0,0 @@
-/*P:300 The I/O mechanism in lguest is simple yet flexible, allowing the Guest
- * to talk to the Launcher or directly to another Guest.  It uses familiar
- * concepts of DMA and interrupts, plus some neat code stolen from
- * futexes... :*/
-
-/* Copyright (C) 2006 Rusty Russell IBM Corporation
- *
- *  This program is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation; either version 2 of the License, or
- *  (at your option) any later version.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
- */
-#include <linux/types.h>
-#include <linux/futex.h>
-#include <linux/jhash.h>
-#include <linux/mm.h>
-#include <linux/highmem.h>
-#include <linux/uaccess.h>
-#include "lg.h"
-
-/*L:300
- * I/O
- *
- * Getting data in and out of the Guest is quite an art.  There are numerous
- * ways to do it, and they all suck differently.  We try to keep things fairly
- * close to "real" hardware so our Guest's drivers don't look like an alien
- * visitation in the middle of the Linux code, and yet make sure that Guests
- * can talk directly to other Guests, not just the Launcher.
- *
- * To do this, the Guest gives us a key when it binds or sends DMA buffers.
- * The key corresponds to a "physical" address inside the Guest (ie. a virtual
- * address inside the Launcher process).  We don't, however, use this key
- * directly.
- *
- * We want Guests which share memory to be able to DMA to each other: two
- * Launchers can mmap memory the same file, then the Guests can communicate.
- * Fortunately, the futex code provides us with a way to get a "union
- * futex_key" corresponding to the memory lying at a virtual address: if the
- * two processes share memory, the "union futex_key" for that memory will match
- * even if the memory is mapped at different addresses in each.  So we always
- * convert the keys to "union futex_key"s to compare them.
- *
- * Before we dive into this though, we need to look at another set of helper
- * routines used throughout the Host kernel code to access Guest memory.
- :*/
-static struct list_head dma_hash[61];
-
-/* An unfortunate side effect of the Linux double-linked list implementation is
- * that there's no good way to statically initialize an array of linked
- * lists. */
-void lguest_io_init(void)
-{
-        unsigned int i;
-
-        for (i = 0; i < ARRAY_SIZE(dma_hash); i++)
-                INIT_LIST_HEAD(&dma_hash[i]);
-}
-
-/* FIXME: allow multi-page lengths. */
-static int check_dma_list(struct lguest *lg, const struct lguest_dma *dma)
-{
-        unsigned int i;
-
-        for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
-                if (!dma->len[i])
-                        return 1;
-                if (!lguest_address_ok(lg, dma->addr[i], dma->len[i]))
-                        goto kill;
-                if (dma->len[i] > PAGE_SIZE)
-                        goto kill;
-                /* We could do over a page, but is it worth it? */
-                if ((dma->addr[i] % PAGE_SIZE) + dma->len[i] > PAGE_SIZE)
-                        goto kill;
-        }
-        return 1;
-
-kill:
-        kill_guest(lg, "bad DMA entry: %u@%#lx", dma->len[i], dma->addr[i]);
-        return 0;
-}
-
-/*L:330 This is our hash function, using the wonderful Jenkins hash.
- *
- * The futex key is a union with three parts: an unsigned long word, a pointer,
- * and an int "offset".  We could use jhash_2words() which takes three u32s.
- * (Ok, the hash functions are great: the naming sucks though).
- *
- * It's nice to be portable to 64-bit platforms, so we use the more generic
- * jhash2(), which takes an array of u32, the number of u32s, and an initial
- * u32 to roll in.  This is uglier, but breaks down to almost the same code on
- * 32-bit platforms like this one.
- *
- * We want a position in the array, so we modulo ARRAY_SIZE(dma_hash) (ie. 61).
- */
-static unsigned int hash(const union futex_key *key)
-{
-        return jhash2((u32*)&key->both.word,
-                      (sizeof(key->both.word)+sizeof(key->both.ptr))/4,
-                      key->both.offset)
-                % ARRAY_SIZE(dma_hash);
-}
-
-/* This is a convenience routine to compare two keys.  It's a much bemoaned C
- * weakness that it doesn't allow '==' on structures or unions, so we have to
- * open-code it like this. */
-static inline int key_eq(const union futex_key *a, const union futex_key *b)
-{
-        return (a->both.word == b->both.word
-                && a->both.ptr == b->both.ptr
-                && a->both.offset == b->both.offset);
-}
-
-/*L:360 OK, when we need to actually free up a Guest's DMA array we do several
- * things, so we have a convenient function to do it.
- *
- * The caller must hold a read lock on dmainfo owner's current->mm->mmap_sem
- * for the drop_futex_key_refs(). */
-static void unlink_dma(struct lguest_dma_info *dmainfo)
-{
-        /* You locked this too, right? */
-        BUG_ON(!mutex_is_locked(&lguest_lock));
-        /* This is how we know that the entry is free. */
-        dmainfo->interrupt = 0;
-        /* Remove it from the hash table. */
-        list_del(&dmainfo->list);
-        /* Drop the references we were holding (to the inode or mm). */
-        drop_futex_key_refs(&dmainfo->key);
-}
-
-/*L:350 This is the routine which we call when the Guest asks to unregister a
- * DMA array attached to a given key.  Returns true if the array was found. */
-static int unbind_dma(struct lguest *lg,
-                      const union futex_key *key,
-                      unsigned long dmas)
-{
-        int i, ret = 0;
-
-        /* We don't bother with the hash table, just look through all this
-         * Guest's DMA arrays. */
-        for (i = 0; i < LGUEST_MAX_DMA; i++) {
-                /* In theory it could have more than one array on the same key,
-                 * or one array on multiple keys, so we check both */
-                if (key_eq(key, &lg->dma[i].key) && dmas == lg->dma[i].dmas) {
-                        unlink_dma(&lg->dma[i]);
-                        ret = 1;
-                        break;
-                }
-        }
-        return ret;
-}
-
-/*L:340 BIND_DMA: this is the hypercall which sets up an array of "struct
- * lguest_dma" for receiving I/O.
- *
- * The Guest wants to bind an array of "struct lguest_dma"s to a particular key
- * to receive input.  This only happens when the Guest is setting up a new
- * device, so it doesn't have to be very fast.
- *
- * It returns 1 on a successful registration (it can fail if we hit the limit
- * of registrations for this Guest).
- */
-int bind_dma(struct lguest *lg,
-             unsigned long ukey, unsigned long dmas, u16 numdmas, u8 interrupt)
-{
-        unsigned int i;
-        int ret = 0;
-        union futex_key key;
-        /* Futex code needs the mmap_sem. */
-        struct rw_semaphore *fshared = &current->mm->mmap_sem;
-
-        /* Invalid interrupt?  (We could kill the guest here). */
-        if (interrupt >= LGUEST_IRQS)
-                return 0;
-
-        /* We need to grab the Big Lguest Lock, because other Guests may be
-         * trying to look through this Guest's DMAs to send something while
-         * we're doing this. */
-        mutex_lock(&lguest_lock);
-        down_read(fshared);
-        if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) {
-                kill_guest(lg, "bad dma key %#lx", ukey);
-                goto unlock;
-        }
-
-        /* We want to keep this key valid once we drop mmap_sem, so we have to
-         * hold a reference. */
-        get_futex_key_refs(&key);
-
-        /* If the Guest specified an interrupt of 0, that means they want to
-         * unregister this array of "struct lguest_dma"s. */
-        if (interrupt == 0)
-                ret = unbind_dma(lg, &key, dmas);
-        else {
-                /* Look through this Guest's dma array for an unused entry. */
-                for (i = 0; i < LGUEST_MAX_DMA; i++) {
-                        /* If the interrupt is non-zero, the entry is already
-                         * used. */
-                        if (lg->dma[i].interrupt)
-                                continue;
-
-                        /* OK, a free one!  Fill on our details. */
-                        lg->dma[i].dmas = dmas;
-                        lg->dma[i].num_dmas = numdmas;
-                        lg->dma[i].next_dma = 0;
-                        lg->dma[i].key = key;
-                        lg->dma[i].guestid = lg->guestid;
-                        lg->dma[i].interrupt = interrupt;
-
-                        /* Now we add it to the hash table: the position
-                         * depends on the futex key that we got. */
-                        list_add(&lg->dma[i].list, &dma_hash[hash(&key)]);
-                        /* Success! */
-                        ret = 1;
-                        goto unlock;
-                }
-        }
-        /* If we didn't find a slot to put the key in, drop the reference
-         * again. */
-        drop_futex_key_refs(&key);
-unlock:
-        /* Unlock and out. */
-        up_read(fshared);
-        mutex_unlock(&lguest_lock);
-        return ret;
-}
-
-/*L:385 Note that our routines to access a different Guest's memory are called
- * lgread_other() and lgwrite_other(): these names emphasize that they are only
- * used when the Guest is *not* the current Guest.
- *
- * The interface for copying from another process's memory is called
- * access_process_vm(), with a final argument of 0 for a read, and 1 for a
- * write.
- *
- * We need lgread_other() to read the destination Guest's "struct lguest_dma"
- * array. */
-static int lgread_other(struct lguest *lg,
-                        void *buf, u32 addr, unsigned bytes)
-{
-        if (!lguest_address_ok(lg, addr, bytes)
-            || access_process_vm(lg->tsk, addr, buf, bytes, 0) != bytes) {
-                memset(buf, 0, bytes);
-                kill_guest(lg, "bad address in registered DMA struct");
-                return 0;
-        }
-        return 1;
-}
-
-/* "lgwrite()" to another Guest: used to update the destination "used_len" once
- * we've transferred data into the buffer. */
-static int lgwrite_other(struct lguest *lg, u32 addr,
-                         const void *buf, unsigned bytes)
-{
-        if (!lguest_address_ok(lg, addr, bytes)
-            || (access_process_vm(lg->tsk, addr, (void *)buf, bytes, 1)
-                != bytes)) {
-                kill_guest(lg, "bad address writing to registered DMA");
-                return 0;
-        }
-        return 1;
-}
-
-/*L:400 This is the generic engine which copies from a source "struct
- * lguest_dma" from this Guest into another Guest's "struct lguest_dma".  The
- * destination Guest's pages have already been mapped, as contained in the
- * pages array.
- *
- * If you're wondering if there's a nice "copy from one process to another"
- * routine, so was I.  But Linux isn't really set up to copy between two
- * unrelated processes, so we have to write it ourselves.
- */
-static u32 copy_data(struct lguest *srclg,
-                     const struct lguest_dma *src,
-                     const struct lguest_dma *dst,
-                     struct page *pages[])
-{
-        unsigned int totlen, si, di, srcoff, dstoff;
-        void *maddr = NULL;
-
-        /* We return the total length transferred. */
-        totlen = 0;
-
-        /* We keep indexes into the source and destination "struct lguest_dma",
-         * and an offset within each region. */
-        si = di = 0;
-        srcoff = dstoff = 0;
-
-        /* We loop until the source or destination is exhausted. */
-        while (si < LGUEST_MAX_DMA_SECTIONS && src->len[si]
-               && di < LGUEST_MAX_DMA_SECTIONS && dst->len[di]) {
-                /* We can only transfer the rest of the src buffer, or as much
-                 * as will fit into the destination buffer. */
-                u32 len = min(src->len[si] - srcoff, dst->len[di] - dstoff);
-
-                /* For systems using "highmem" we need to use kmap() to access
-                 * the page we want.  We often use the same page over and over,
-                 * so rather than kmap() it on every loop, we set the maddr
-                 * pointer to NULL when we need to move to the next
-                 * destination page. */
-                if (!maddr)
-                        maddr = kmap(pages[di]);
-
-                /* Copy directly from (this Guest's) source address to the
-                 * destination Guest's kmap()ed buffer.  Note that maddr points
-                 * to the start of the page: we need to add the offset of the
-                 * destination address and offset within the buffer. */
-
-                /* FIXME: This is not completely portable.  I looked at
-                 * copy_to_user_page(), and some arch's seem to need special
-                 * flushes.  x86 is fine. */
-                if (copy_from_user(maddr + (dst->addr[di] + dstoff)%PAGE_SIZE,
-                                   (void __user *)src->addr[si], len) != 0) {
-                        /* If a copy failed, it's the source's fault. */
-                        kill_guest(srclg, "bad address in sending DMA");
-                        totlen = 0;
-                        break;
-                }
-
-                /* Increment the total and src & dst offsets */
-                totlen += len;
-                srcoff += len;
-                dstoff += len;
-
-                /* Presumably we reached the end of the src or dest buffers: */
-                if (srcoff == src->len[si]) {
-                        /* Move to the next buffer at offset 0 */
-                        si++;
-                        srcoff = 0;
-                }
-                if (dstoff == dst->len[di]) {
-                        /* We need to unmap that destination page and reset
-                         * maddr ready for the next one. */
-                        kunmap(pages[di]);
-                        maddr = NULL;
-                        di++;
-                        dstoff = 0;
-                }
-        }
-
-        /* If we still had a page mapped at the end, unmap now. */
-        if (maddr)
-                kunmap(pages[di]);
-
-        return totlen;
-}
-
-/*L:390 This is how we transfer a "struct lguest_dma" from the source Guest
- * (the current Guest which called SEND_DMA) to another Guest. */
-static u32 do_dma(struct lguest *srclg, const struct lguest_dma *src,
-                  struct lguest *dstlg, const struct lguest_dma *dst)
-{
-        int i;
-        u32 ret;
-        struct page *pages[LGUEST_MAX_DMA_SECTIONS];
-
-        /* We check that both source and destination "struct lguest_dma"s are
-         * within the bounds of the source and destination Guests */
-        if (!check_dma_list(dstlg, dst) || !check_dma_list(srclg, src))
-                return 0;
-
-        /* We need to map the pages which correspond to each parts of
-         * destination buffer. */
-        for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
-                if (dst->len[i] == 0)
-                        break;
-                /* get_user_pages() is a complicated function, especially since
-                 * we only want a single page.  But it works, and returns the
-                 * number of pages.  Note that we're holding the destination's
-                 * mmap_sem, as get_user_pages() requires. */
-                if (get_user_pages(dstlg->tsk, dstlg->mm,
-                                   dst->addr[i], 1, 1, 1, pages+i, NULL)
-                    != 1) {
-                        /* This means the destination gave us a bogus buffer */
-                        kill_guest(dstlg, "Error mapping DMA pages");
-                        ret = 0;
-                        goto drop_pages;
-                }
-        }
-
-        /* Now copy the data until we run out of src or dst. */
-        ret = copy_data(srclg, src, dst, pages);
-
-drop_pages:
-        while (--i >= 0)
-                put_page(pages[i]);
-        return ret;
-}
-
-/*L:380 Transferring data from one Guest to another is not as simple as I'd
- * like.  We've found the "struct lguest_dma_info" bound to the same address as
- * the send, we need to copy into it.
- *
- * This function returns true if the destination array was empty. */
-static int dma_transfer(struct lguest *srclg,
-                        unsigned long udma,
-                        struct lguest_dma_info *dst)
-{
-        struct lguest_dma dst_dma, src_dma;
-        struct lguest *dstlg;
-        u32 i, dma = 0;
-
-        /* From the "struct lguest_dma_info" we found in the hash, grab the
-         * Guest. */
-        dstlg = &lguests[dst->guestid];
-        /* Read in the source "struct lguest_dma" handed to SEND_DMA. */
-        lgread(srclg, &src_dma, udma, sizeof(src_dma));
-
-        /* We need the destination's mmap_sem, and we already hold the source's
-         * mmap_sem for the futex key lookup.  Normally this would suggest that
-         * we could deadlock if the destination Guest was trying to send to
-         * this source Guest at the same time, which is another reason that all
-         * I/O is done under the big lguest_lock. */
-        down_read(&dstlg->mm->mmap_sem);
-
-        /* Look through the destination DMA array for an available buffer. */
-        for (i = 0; i < dst->num_dmas; i++) {
-                /* We keep a "next_dma" pointer which often helps us avoid
-                 * looking at lots of previously-filled entries. */
-                dma = (dst->next_dma + i) % dst->num_dmas;
-                if (!lgread_other(dstlg, &dst_dma,
-                                  dst->dmas + dma * sizeof(struct lguest_dma),
-                                  sizeof(dst_dma))) {
-                        goto fail;
-                }
-                if (!dst_dma.used_len)
-                        break;
-        }
-
-        /* If we found a buffer, we do the actual data copy. */
-        if (i != dst->num_dmas) {
-                unsigned long used_lenp;
-                unsigned int ret;
-
-                ret = do_dma(srclg, &src_dma, dstlg, &dst_dma);
-                /* Put used length in the source "struct lguest_dma"'s used_len
-                 * field.  It's a little tricky to figure out where that is,
-                 * though. */
-                lgwrite_u32(srclg,
-                            udma+offsetof(struct lguest_dma, used_len), ret);
-                /* Tranferring 0 bytes is OK if the source buffer was empty. */
-                if (ret == 0 && src_dma.len[0] != 0)
-                        goto fail;
-
-                /* The destination Guest might be running on a different CPU:
-                 * we have to make sure that it will see the "used_len" field
-                 * change to non-zero *after* it sees the data we copied into
-                 * the buffer.  Hence a write memory barrier. */
-                wmb();
-                /* Figuring out where the destination's used_len field for this
-                 * "struct lguest_dma" in the array is also a little ugly. */
-                used_lenp = dst->dmas
-                        + dma * sizeof(struct lguest_dma)
-                        + offsetof(struct lguest_dma, used_len);
-                lgwrite_other(dstlg, used_lenp, &ret, sizeof(ret));
-                /* Move the cursor for next time. */
-                dst->next_dma++;
-        }
-        up_read(&dstlg->mm->mmap_sem);
-
-        /* We trigger the destination interrupt, even if the destination was
-         * empty and we didn't transfer anything: this gives them a chance to
-         * wake up and refill. */
-        set_bit(dst->interrupt, dstlg->irqs_pending);
-        /* Wake up the destination process. */
-        wake_up_process(dstlg->tsk);
-        /* If we passed the last "struct lguest_dma", the receive had no
-         * buffers left. */
-        return i == dst->num_dmas;
-
-fail:
-        up_read(&dstlg->mm->mmap_sem);
-        return 0;
-}
-
-/*L:370 This is the counter-side to the BIND_DMA hypercall; the SEND_DMA
- * hypercall.  We find out who's listening, and send to them. */
-void send_dma(struct lguest *lg, unsigned long ukey, unsigned long udma)
-{
-        union futex_key key;
-        int empty = 0;
-        struct rw_semaphore *fshared = &current->mm->mmap_sem;
-
-again:
-        mutex_lock(&lguest_lock);
-        down_read(fshared);
-        /* Get the futex key for the key the Guest gave us */
-        if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) {
-                kill_guest(lg, "bad sending DMA key");
-                goto unlock;
-        }
-        /* Since the key must be a multiple of 4, the futex key uses the lower
-         * bit of the "offset" field (which would always be 0) to indicate a
-         * mapping which is shared with other processes (ie. Guests). */
-        if (key.shared.offset & 1) {
-                struct lguest_dma_info *i;
-                /* Look through the hash for other Guests. */
-                list_for_each_entry(i, &dma_hash[hash(&key)], list) {
-                        /* Don't send to ourselves. */
-                        if (i->guestid == lg->guestid)
-                                continue;
-                        if (!key_eq(&key, &i->key))
-                                continue;
-
-                        /* If dma_transfer() tells us the destination has no
-                         * available buffers, we increment "empty". */
-                        empty += dma_transfer(lg, udma, i);
-                        break;
-                }
-                /* If the destination is empty, we release our locks and
-                 * give the destination Guest a brief chance to restock. */
-                if (empty == 1) {
-                        /* Give any recipients one chance to restock. */
-                        up_read(&current->mm->mmap_sem);
-                        mutex_unlock(&lguest_lock);
-                        /* Next time, we won't try again. */
-                        empty++;
-                        goto again;
-                }
-        } else {
-                /* Private mapping: Guest is sending to its Launcher.  We set
-                 * the "dma_is_pending" flag so that the main loop will exit
-                 * and the Launcher's read() from /dev/lguest will return. */
-                lg->dma_is_pending = 1;
-                lg->pending_dma = udma;
-                lg->pending_key = ukey;
-        }
-unlock:
-        up_read(fshared);
-        mutex_unlock(&lguest_lock);
-}
-/*:*/
-
-void release_all_dma(struct lguest *lg)
-{
-        unsigned int i;
-
-        BUG_ON(!mutex_is_locked(&lguest_lock));
-
-        down_read(&lg->mm->mmap_sem);
-        for (i = 0; i < LGUEST_MAX_DMA; i++) {
-                if (lg->dma[i].interrupt)
-                        unlink_dma(&lg->dma[i]);
-        }
-        up_read(&lg->mm->mmap_sem);
-}
-
-/*M:007 We only return a single DMA buffer to the Launcher, but it would be
- * more efficient to return a pointer to the entire array of DMA buffers, which
- * it can cache and choose one whenever it wants.
- *
- * Currently the Launcher uses a write to /dev/lguest, and the return value is
- * the address of the DMA structure with the interrupt number placed in
- * dma->used_len.  If we wanted to return the entire array, we need to return
- * the address, array size and interrupt number: this seems to require an
- * ioctl(). :*/
-
-/*L:320 This routine looks for a DMA buffer registered by the Guest on the
- * given key (using the BIND_DMA hypercall). */
-unsigned long get_dma_buffer(struct lguest *lg,
-                             unsigned long ukey, unsigned long *interrupt)
-{
-        unsigned long ret = 0;
-        union futex_key key;
-        struct lguest_dma_info *i;
-        struct rw_semaphore *fshared = &current->mm->mmap_sem;
-
-        /* Take the Big Lguest Lock to stop other Guests sending this Guest DMA
-         * at the same time. */
-        mutex_lock(&lguest_lock);
-        /* To match between Guests sharing the same underlying memory we steal
-         * code from the futex infrastructure.  This requires that we hold the
-         * "mmap_sem" for our process (the Launcher), and pass it to the futex
-         * code. */
-        down_read(fshared);
-
-        /* This can fail if it's not a valid address, or if the address is not
-         * divisible by 4 (the futex code needs that, we don't really). */
-        if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) {
-                kill_guest(lg, "bad registered DMA buffer");
-                goto unlock;
-        }
-        /* Search the hash table for matching entries (the Launcher can only
-         * send to its own Guest for the moment, so the entry must be for this
-         * Guest) */
-        list_for_each_entry(i, &dma_hash[hash(&key)], list) {
-                if (key_eq(&key, &i->key) && i->guestid == lg->guestid) {
-                        unsigned int j;
-                        /* Look through the registered DMA array for an
-                         * available buffer. */
-                        for (j = 0; j < i->num_dmas; j++) {
-                                struct lguest_dma dma;
-
-                                ret = i->dmas + j * sizeof(struct lguest_dma);
-                                lgread(lg, &dma, ret, sizeof(dma));
-                                if (dma.used_len == 0)
-                                        break;
-                        }
-                        /* Store the interrupt the Guest wants when the buffer
-                         * is used. */
-                        *interrupt = i->interrupt;
-                        break;
-                }
-        }
-unlock:
-        up_read(fshared);
-        mutex_unlock(&lguest_lock);
-        return ret;
-}
-/*:*/
-
-/*L:410 This really has completed the Launcher.  Not only have we now finished
- * the longest chapter in our journey, but this also means we are over halfway
- * through!
- *
- * Enough prevaricating around the bush: it is time for us to dive into the
- * core of the Host, in "make Host".
- */
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 64f0abed317c..d9144beca82c 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -1,119 +1,25 @@
 #ifndef _LGUEST_H
 #define _LGUEST_H
 
-#include <asm/desc.h>
-
-#define GDT_ENTRY_LGUEST_CS     10
-#define GDT_ENTRY_LGUEST_DS     11
-#define LGUEST_CS               (GDT_ENTRY_LGUEST_CS * 8)
-#define LGUEST_DS               (GDT_ENTRY_LGUEST_DS * 8)
-
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/stringify.h>
-#include <linux/binfmts.h>
-#include <linux/futex.h>
 #include <linux/lguest.h>
 #include <linux/lguest_launcher.h>
 #include <linux/wait.h>
 #include <linux/err.h>
 #include <asm/semaphore.h>
-#include "irq_vectors.h"
-
-#define GUEST_PL 1
 
-struct lguest_regs
-{
-        /* Manually saved part. */
-        unsigned long ebx, ecx, edx;
-        unsigned long esi, edi, ebp;
-        unsigned long gs;
-        unsigned long eax;
-        unsigned long fs, ds, es;
-        unsigned long trapnum, errcode;
-        /* Trap pushed part */
-        unsigned long eip;
-        unsigned long cs;
-        unsigned long eflags;
-        unsigned long esp;
-        unsigned long ss;
-};
+#include <asm/lguest.h>
 
 void free_pagetables(void);
 int init_pagetables(struct page **switcher_page, unsigned int pages);
 
-/* Full 4G segment descriptors, suitable for CS and DS. */
-#define FULL_EXEC_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9b00})
-#define FULL_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9300})
-
-struct lguest_dma_info
-{
-        struct list_head list;
-        union futex_key key;
-        unsigned long dmas;
-        u16 next_dma;
-        u16 num_dmas;
-        u16 guestid;
-        u8 interrupt;   /* 0 when not registered */
-};
-
-/*H:310 The page-table code owes a great debt of gratitude to Andi Kleen.  He
- * reviewed the original code which used "u32" for all page table entries, and
- * insisted that it would be far clearer with explicit typing.  I thought it
- * was overkill, but he was right: it is much clearer than it was before.
- *
- * We have separate types for the Guest's ptes & pgds and the shadow ptes &
- * pgds.  There's already a Linux type for these (pte_t and pgd_t) but they
- * change depending on kernel config options (PAE). */
-
-/* Each entry is identical: lower 12 bits of flags and upper 20 bits for the
- * "page frame number" (0 == first physical page, etc).  They are different
- * types so the compiler will warn us if we mix them improperly. */
-typedef union {
-        struct { unsigned flags:12, pfn:20; };
-        struct { unsigned long val; } raw;
-} spgd_t;
-typedef union {
-        struct { unsigned flags:12, pfn:20; };
-        struct { unsigned long val; } raw;
-} spte_t;
-typedef union {
-        struct { unsigned flags:12, pfn:20; };
-        struct { unsigned long val; } raw;
-} gpgd_t;
-typedef union {
-        struct { unsigned flags:12, pfn:20; };
-        struct { unsigned long val; } raw;
-} gpte_t;
-
-/* We have two convenient macros to convert a "raw" value as handed to us by
- * the Guest into the correct Guest PGD or PTE type. */
-#define mkgpte(_val) ((gpte_t){.raw.val = _val})
-#define mkgpgd(_val) ((gpgd_t){.raw.val = _val})
-/*:*/
-
 struct pgdir
 {
-        unsigned long cr3;
-        spgd_t *pgdir;
-};
-
-/* This is a guest-specific page (mapped ro) into the guest. */
-struct lguest_ro_state
-{
-        /* Host information we need to restore when we switch back. */
-        u32 host_cr3;
-        struct Xgt_desc_struct host_idt_desc;
-        struct Xgt_desc_struct host_gdt_desc;
-        u32 host_sp;
-
-        /* Fields which are used when guest is running. */
-        struct Xgt_desc_struct guest_idt_desc;
-        struct Xgt_desc_struct guest_gdt_desc;
-        struct i386_hw_tss guest_tss;
-        struct desc_struct guest_idt[IDT_ENTRIES];
-        struct desc_struct guest_gdt[GDT_ENTRIES];
+        unsigned long gpgdir;
+        pgd_t *pgdir;
 };
 
 /* We have two pages shared with guests, per cpu.  */
@@ -141,9 +47,11 @@ struct lguest
         struct lguest_data __user *lguest_data;
         struct task_struct *tsk;
         struct mm_struct *mm;   /* == tsk->mm, but that becomes NULL on exit */
-        u16 guestid;
         u32 pfn_limit;
-        u32 page_offset;
+        /* This provides the offset to the base of guest-physical
+         * memory in the Launcher. */
+        void __user *mem_base;
+        unsigned long kernel_address;
         u32 cr2;
         int halted;
         int ts;
@@ -151,6 +59,9 @@ struct lguest
         u32 esp1;
         u8 ss1;
 
+        /* If a hypercall was asked for, this points to the arguments. */
+        struct hcall_args *hcall;
+
         /* Do we need to stop what we're doing and return to userspace? */
         int break_out;
         wait_queue_head_t break_wq;
@@ -167,24 +78,15 @@ struct lguest
         struct task_struct *wake;
 
         unsigned long noirq_start, noirq_end;
-        int dma_is_pending;
-        unsigned long pending_dma; /* struct lguest_dma */
-        unsigned long pending_key; /* address they're sending to */
+        unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
 
         unsigned int stack_pages;
         u32 tsc_khz;
 
-        struct lguest_dma_info dma[LGUEST_MAX_DMA];
-
         /* Dead? */
         const char *dead;
 
-        /* The GDT entries copied into lguest_ro_state when running. */
-        struct desc_struct gdt[GDT_ENTRIES];
-
-        /* The IDT entries: some copied into lguest_ro_state when running. */
-        struct desc_struct idt[FIRST_EXTERNAL_VECTOR+LGUEST_IRQS];
-        struct desc_struct syscall_idt;
+        struct lguest_arch arch;
 
         /* Virtual clock device */
         struct hrtimer hrt;
@@ -193,19 +95,38 @@ struct lguest
         DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
 };
 
-extern struct lguest lguests[];
 extern struct mutex lguest_lock;
 
 /* core.c: */
-u32 lgread_u32(struct lguest *lg, unsigned long addr);
-void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val);
-void lgread(struct lguest *lg, void *buf, unsigned long addr, unsigned len);
-void lgwrite(struct lguest *lg, unsigned long, const void *buf, unsigned len);
-int find_free_guest(void);
 int lguest_address_ok(const struct lguest *lg,
                       unsigned long addr, unsigned long len);
+void __lgread(struct lguest *, void *, unsigned long, unsigned);
+void __lgwrite(struct lguest *, unsigned long, const void *, unsigned);
+
+/*L:306 Using memory-copy operations like that is usually inconvient, so we
+ * have the following helper macros which read and write a specific type (often
+ * an unsigned long).
+ *
+ * This reads into a variable of the given type then returns that. */
+#define lgread(lg, addr, type)                                          \
+        ({ type _v; __lgread((lg), &_v, (addr), sizeof(_v)); _v; })
+
+/* This checks that the variable is of the given type, then writes it out. */
+#define lgwrite(lg, addr, type, val)                            \
+        do {                                                    \
+                typecheck(type, val);                           \
+                __lgwrite((lg), (addr), &(val), sizeof(val));   \
+        } while(0)
+/* (end of memory access helper routines) :*/
+
 int run_guest(struct lguest *lg, unsigned long __user *user);
 
+/* Helper macros to obtain the first 12 or the last 20 bits, this is only the
+ * first step in the migration to the kernel types.  pte_pfn is already defined
+ * in the kernel. */
+#define pgd_flags(x)    (pgd_val(x) & ~PAGE_MASK)
+#define pte_flags(x)    (pte_val(x) & ~PAGE_MASK)
+#define pgd_pfn(x)      (pgd_val(x) >> PAGE_SHIFT)
 
 /* interrupts_and_traps.c: */
 void maybe_do_interrupt(struct lguest *lg);
@@ -219,6 +140,9 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
                 const unsigned long *def);
 void guest_set_clockevent(struct lguest *lg, unsigned long delta);
 void init_clockdev(struct lguest *lg);
+bool check_syscall_vector(struct lguest *lg);
+int init_interrupts(void);
+void free_interrupts(void);
 
 /* segments.c: */
 void setup_default_gdt_entries(struct lguest_ro_state *state);
@@ -232,28 +156,33 @@ void copy_gdt_tls(const struct lguest *lg, struct desc_struct *gdt);
 int init_guest_pagetable(struct lguest *lg, unsigned long pgtable);
 void free_guest_pagetable(struct lguest *lg);
 void guest_new_pagetable(struct lguest *lg, unsigned long pgtable);
-void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 i);
+void guest_set_pmd(struct lguest *lg, unsigned long gpgdir, u32 i);
 void guest_pagetable_clear_all(struct lguest *lg);
 void guest_pagetable_flush_user(struct lguest *lg);
-void guest_set_pte(struct lguest *lg, unsigned long cr3,
-                   unsigned long vaddr, gpte_t val);
+void guest_set_pte(struct lguest *lg, unsigned long gpgdir,
+                   unsigned long vaddr, pte_t val);
 void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages);
 int demand_page(struct lguest *info, unsigned long cr2, int errcode);
 void pin_page(struct lguest *lg, unsigned long vaddr);
+unsigned long guest_pa(struct lguest *lg, unsigned long vaddr);
+void page_table_guest_data_init(struct lguest *lg);
+
+/* <arch>/core.c: */
+void lguest_arch_host_init(void);
+void lguest_arch_host_fini(void);
+void lguest_arch_run_guest(struct lguest *lg);
+void lguest_arch_handle_trap(struct lguest *lg);
+int lguest_arch_init_hypercalls(struct lguest *lg);
+int lguest_arch_do_hcall(struct lguest *lg, struct hcall_args *args);
+void lguest_arch_setup_regs(struct lguest *lg, unsigned long start);
+
+/* <arch>/switcher.S: */
+extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
 
 /* lguest_user.c: */
 int lguest_device_init(void);
 void lguest_device_remove(void);
 
-/* io.c: */
-void lguest_io_init(void);
-int bind_dma(struct lguest *lg,
-             unsigned long key, unsigned long udma, u16 numdmas, u8 interrupt);
-void send_dma(struct lguest *info, unsigned long key, unsigned long udma);
-void release_all_dma(struct lguest *lg);
-unsigned long get_dma_buffer(struct lguest *lg, unsigned long key,
-                             unsigned long *interrupt);
-
 /* hypercalls.c: */
 void do_hypercalls(struct lguest *lg);
 void write_timestamp(struct lguest *lg);
@@ -292,9 +221,5 @@ do {								\
 } while(0)
 /* (End of aside) :*/
 
-static inline unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
-{
-        return vaddr - lg->page_offset;
-}
 #endif  /* __ASSEMBLY__ */
 #endif  /* _LGUEST_H */
diff --git a/drivers/lguest/lguest.c b/drivers/lguest/lguest.c
deleted file mode 100644
index 3ba337dde857..000000000000
--- a/drivers/lguest/lguest.c
+++ /dev/null
@@ -1,1108 +0,0 @@
-/*P:010
- * A hypervisor allows multiple Operating Systems to run on a single machine.
- * To quote David Wheeler: "Any problem in computer science can be solved with
- * another layer of indirection."
- *
- * We keep things simple in two ways.  First, we start with a normal Linux
- * kernel and insert a module (lg.ko) which allows us to run other Linux
- * kernels the same way we'd run processes.  We call the first kernel the Host,
- * and the others the Guests.  The program which sets up and configures Guests
- * (such as the example in Documentation/lguest/lguest.c) is called the
- * Launcher.
- *
- * Secondly, we only run specially modified Guests, not normal kernels.  When
- * you set CONFIG_LGUEST to 'y' or 'm', this automatically sets
- * CONFIG_LGUEST_GUEST=y, which compiles this file into the kernel so it knows
- * how to be a Guest.  This means that you can use the same kernel you boot
- * normally (ie. as a Host) as a Guest.
- *
- * These Guests know that they cannot do privileged operations, such as disable
- * interrupts, and that they have to ask the Host to do such things explicitly.
- * This file consists of all the replacements for such low-level native
- * hardware operations: these special Guest versions call the Host.
- *
- * So how does the kernel know it's a Guest?  The Guest starts at a special
- * entry point marked with a magic string, which sets up a few things then
- * calls here.  We replace the native functions various "paravirt" structures
- * with our Guest versions, then boot like normal. :*/
-
-/*
- * Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
- * NON INFRINGEMENT.  See the GNU General Public License for more
- * details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-#include <linux/kernel.h>
-#include <linux/start_kernel.h>
-#include <linux/string.h>
-#include <linux/console.h>
-#include <linux/screen_info.h>
-#include <linux/irq.h>
-#include <linux/interrupt.h>
-#include <linux/clocksource.h>
-#include <linux/clockchips.h>
-#include <linux/lguest.h>
-#include <linux/lguest_launcher.h>
-#include <linux/lguest_bus.h>
-#include <asm/paravirt.h>
-#include <asm/param.h>
-#include <asm/page.h>
-#include <asm/pgtable.h>
-#include <asm/desc.h>
-#include <asm/setup.h>
-#include <asm/e820.h>
-#include <asm/mce.h>
-#include <asm/io.h>
-
-/*G:010 Welcome to the Guest!
- *
- * The Guest in our tale is a simple creature: identical to the Host but
- * behaving in simplified but equivalent ways.  In particular, the Guest is the
- * same kernel as the Host (or at least, built from the same source code). :*/
-
-/* Declarations for definitions in lguest_guest.S */
-extern char lguest_noirq_start[], lguest_noirq_end[];
-extern const char lgstart_cli[], lgend_cli[];
-extern const char lgstart_sti[], lgend_sti[];
-extern const char lgstart_popf[], lgend_popf[];
-extern const char lgstart_pushf[], lgend_pushf[];
-extern const char lgstart_iret[], lgend_iret[];
-extern void lguest_iret(void);
-
-struct lguest_data lguest_data = {
-        .hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
-        .noirq_start = (u32)lguest_noirq_start,
-        .noirq_end = (u32)lguest_noirq_end,
-        .blocked_interrupts = { 1 }, /* Block timer interrupts */
-};
-struct lguest_device_desc *lguest_devices;
-static cycle_t clock_base;
-
-/*G:035 Notice the lazy_hcall() above, rather than hcall().  This is our first
- * real optimization trick!
- *
- * When lazy_mode is set, it means we're allowed to defer all hypercalls and do
- * them as a batch when lazy_mode is eventually turned off.  Because hypercalls
- * are reasonably expensive, batching them up makes sense.  For example, a
- * large mmap might update dozens of page table entries: that code calls
- * paravirt_enter_lazy_mmu(), does the dozen updates, then calls
- * lguest_leave_lazy_mode().
- *
- * So, when we're in lazy mode, we call async_hypercall() to store the call for
- * future processing.  When lazy mode is turned off we issue a hypercall to
- * flush the stored calls.
- */
-static void lguest_leave_lazy_mode(void)
-{
-        paravirt_leave_lazy(paravirt_get_lazy_mode());
-        hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
-}
-
-static void lazy_hcall(unsigned long call,
-                       unsigned long arg1,
-                       unsigned long arg2,
-                       unsigned long arg3)
-{
-        if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
-                hcall(call, arg1, arg2, arg3);
-        else
-                async_hcall(call, arg1, arg2, arg3);
-}
-
-/* async_hcall() is pretty simple: I'm quite proud of it really.  We have a
- * ring buffer of stored hypercalls which the Host will run though next time we
- * do a normal hypercall.  Each entry in the ring has 4 slots for the hypercall
- * arguments, and a "hcall_status" word which is 0 if the call is ready to go,
- * and 255 once the Host has finished with it.
- *
- * If we come around to a slot which hasn't been finished, then the table is
- * full and we just make the hypercall directly.  This has the nice side
- * effect of causing the Host to run all the stored calls in the ring buffer
- * which empties it for next time! */
-void async_hcall(unsigned long call,
-                 unsigned long arg1, unsigned long arg2, unsigned long arg3)
-{
-        /* Note: This code assumes we're uniprocessor. */
-        static unsigned int next_call;
-        unsigned long flags;
-
-        /* Disable interrupts if not already disabled: we don't want an
-         * interrupt handler making a hypercall while we're already doing
-         * one! */
-        local_irq_save(flags);
-        if (lguest_data.hcall_status[next_call] != 0xFF) {
-                /* Table full, so do normal hcall which will flush table. */
-                hcall(call, arg1, arg2, arg3);
-        } else {
-                lguest_data.hcalls[next_call].eax = call;
-                lguest_data.hcalls[next_call].edx = arg1;
-                lguest_data.hcalls[next_call].ebx = arg2;
-                lguest_data.hcalls[next_call].ecx = arg3;
-                /* Arguments must all be written before we mark it to go */
-                wmb();
-                lguest_data.hcall_status[next_call] = 0;
-                if (++next_call == LHCALL_RING_SIZE)
-                        next_call = 0;
-        }
-        local_irq_restore(flags);
-}
-/*:*/
-
-/* Wrappers for the SEND_DMA and BIND_DMA hypercalls.  This is mainly because
- * Jeff Garzik complained that __pa() should never appear in drivers, and this
- * helps remove most of them.   But also, it wraps some ugliness. */
-void lguest_send_dma(unsigned long key, struct lguest_dma *dma)
-{
-        /* The hcall might not write this if something goes wrong */
-        dma->used_len = 0;
-        hcall(LHCALL_SEND_DMA, key, __pa(dma), 0);
-}
-
-int lguest_bind_dma(unsigned long key, struct lguest_dma *dmas,
-                    unsigned int num, u8 irq)
-{
-        /* This is the only hypercall which actually wants 5 arguments, and we
-         * only support 4.  Fortunately the interrupt number is always less
-         * than 256, so we can pack it with the number of dmas in the final
-         * argument.  */
-        if (!hcall(LHCALL_BIND_DMA, key, __pa(dmas), (num << 8) | irq))
-                return -ENOMEM;
-        return 0;
-}
-
-/* Unbinding is the same hypercall as binding, but with 0 num & irq. */
-void lguest_unbind_dma(unsigned long key, struct lguest_dma *dmas)
-{
-        hcall(LHCALL_BIND_DMA, key, __pa(dmas), 0);
-}
-
-/* For guests, device memory can be used as normal memory, so we cast away the
- * __iomem to quieten sparse. */
-void *lguest_map(unsigned long phys_addr, unsigned long pages)
-{
-        return (__force void *)ioremap(phys_addr, PAGE_SIZE*pages);
-}
-
-void lguest_unmap(void *addr)
-{
-        iounmap((__force void __iomem *)addr);
-}
-
-/*G:033
- * Here are our first native-instruction replacements: four functions for
- * interrupt control.
- *
- * The simplest way of implementing these would be to have "turn interrupts
- * off" and "turn interrupts on" hypercalls.  Unfortunately, this is too slow:
- * these are by far the most commonly called functions of those we override.
- *
- * So instead we keep an "irq_enabled" field inside our "struct lguest_data",
- * which the Guest can update with a single instruction.  The Host knows to
- * check there when it wants to deliver an interrupt.
- */
-
-/* save_flags() is expected to return the processor state (ie. "eflags").  The
- * eflags word contains all kind of stuff, but in practice Linux only cares
- * about the interrupt flag.  Our "save_flags()" just returns that. */
-static unsigned long save_fl(void)
-{
-        return lguest_data.irq_enabled;
-}
-
-/* "restore_flags" just sets the flags back to the value given. */
-static void restore_fl(unsigned long flags)
-{
-        lguest_data.irq_enabled = flags;
-}
-
-/* Interrupts go off... */
-static void irq_disable(void)
-{
-        lguest_data.irq_enabled = 0;
-}
-
-/* Interrupts go on... */
-static void irq_enable(void)
-{
-        lguest_data.irq_enabled = X86_EFLAGS_IF;
-}
-/*:*/
-/*M:003 Note that we don't check for outstanding interrupts when we re-enable
- * them (or when we unmask an interrupt).  This seems to work for the moment,
- * since interrupts are rare and we'll just get the interrupt on the next timer
- * tick, but when we turn on CONFIG_NO_HZ, we should revisit this.  One way
- * would be to put the "irq_enabled" field in a page by itself, and have the
- * Host write-protect it when an interrupt comes in when irqs are disabled.
- * There will then be a page fault as soon as interrupts are re-enabled. :*/
-
-/*G:034
- * The Interrupt Descriptor Table (IDT).
- *
- * The IDT tells the processor what to do when an interrupt comes in.  Each
- * entry in the table is a 64-bit descriptor: this holds the privilege level,
- * address of the handler, and... well, who cares?  The Guest just asks the
- * Host to make the change anyway, because the Host controls the real IDT.
- */
-static void lguest_write_idt_entry(struct desc_struct *dt,
-                                   int entrynum, u32 low, u32 high)
-{
-        /* Keep the local copy up to date. */
-        write_dt_entry(dt, entrynum, low, high);
-        /* Tell Host about this new entry. */
-        hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, low, high);
-}
-
-/* Changing to a different IDT is very rare: we keep the IDT up-to-date every
- * time it is written, so we can simply loop through all entries and tell the
- * Host about them. */
-static void lguest_load_idt(const struct Xgt_desc_struct *desc)
-{
-        unsigned int i;
-        struct desc_struct *idt = (void *)desc->address;
-
-        for (i = 0; i < (desc->size+1)/8; i++)
-                hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b);
-}
-
-/*
- * The Global Descriptor Table.
- *
- * The Intel architecture defines another table, called the Global Descriptor
- * Table (GDT).  You tell the CPU where it is (and its size) using the "lgdt"
- * instruction, and then several other instructions refer to entries in the
- * table.  There are three entries which the Switcher needs, so the Host simply
- * controls the entire thing and the Guest asks it to make changes using the
- * LOAD_GDT hypercall.
- *
- * This is the opposite of the IDT code where we have a LOAD_IDT_ENTRY
- * hypercall and use that repeatedly to load a new IDT.  I don't think it
- * really matters, but wouldn't it be nice if they were the same?
- */
-static void lguest_load_gdt(const struct Xgt_desc_struct *desc)
-{
-        BUG_ON((desc->size+1)/8 != GDT_ENTRIES);
-        hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0);
-}
-
-/* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
- * then tell the Host to reload the entire thing.  This operation is so rare
- * that this naive implementation is reasonable. */
-static void lguest_write_gdt_entry(struct desc_struct *dt,
-                                   int entrynum, u32 low, u32 high)
-{
-        write_dt_entry(dt, entrynum, low, high);
-        hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0);
-}
-
-/* OK, I lied.  There are three "thread local storage" GDT entries which change
- * on every context switch (these three entries are how glibc implements
- * __thread variables).  So we have a hypercall specifically for this case. */
-static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
-{
-        /* There's one problem which normal hardware doesn't have: the Host
-         * can't handle us removing entries we're currently using.  So we clear
-         * the GS register here: if it's needed it'll be reloaded anyway. */
-        loadsegment(gs, 0);
-        lazy_hcall(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu, 0);
-}
-
-/*G:038 That's enough excitement for now, back to ploughing through each of
- * the different pv_ops structures (we're about 1/3 of the way through).
- *
- * This is the Local Descriptor Table, another weird Intel thingy.  Linux only
- * uses this for some strange applications like Wine.  We don't do anything
- * here, so they'll get an informative and friendly Segmentation Fault. */
-static void lguest_set_ldt(const void *addr, unsigned entries)
-{
-}
-
-/* This loads a GDT entry into the "Task Register": that entry points to a
- * structure called the Task State Segment.  Some comments scattered though the
- * kernel code indicate that this used for task switching in ages past, along
- * with blood sacrifice and astrology.
- *
- * Now there's nothing interesting in here that we don't get told elsewhere.
- * But the native version uses the "ltr" instruction, which makes the Host
- * complain to the Guest about a Segmentation Fault and it'll oops.  So we
- * override the native version with a do-nothing version. */
-static void lguest_load_tr_desc(void)
-{
-}
-
-/* The "cpuid" instruction is a way of querying both the CPU identity
- * (manufacturer, model, etc) and its features.  It was introduced before the
- * Pentium in 1993 and keeps getting extended by both Intel and AMD.  As you
- * might imagine, after a decade and a half this treatment, it is now a giant
- * ball of hair.  Its entry in the current Intel manual runs to 28 pages.
- *
- * This instruction even it has its own Wikipedia entry.  The Wikipedia entry
- * has been translated into 4 languages.  I am not making this up!
- *
- * We could get funky here and identify ourselves as "GenuineLguest", but
- * instead we just use the real "cpuid" instruction.  Then I pretty much turned
- * off feature bits until the Guest booted.  (Don't say that: you'll damage
- * lguest sales!)  Shut up, inner voice!  (Hey, just pointing out that this is
- * hardly future proof.)  Noone's listening!  They don't like you anyway,
- * parenthetic weirdo!
- *
- * Replacing the cpuid so we can turn features off is great for the kernel, but
- * anyone (including userspace) can just use the raw "cpuid" instruction and
- * the Host won't even notice since it isn't privileged.  So we try not to get
- * too worked up about it. */
-static void lguest_cpuid(unsigned int *eax, unsigned int *ebx,
-                         unsigned int *ecx, unsigned int *edx)
-{
-        int function = *eax;
-
-        native_cpuid(eax, ebx, ecx, edx);
-        switch (function) {
-        case 1: /* Basic feature request. */
-                /* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
-                *ecx &= 0x00002201;
-                /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
-                *edx &= 0x07808101;
-                /* The Host can do a nice optimization if it knows that the
-                 * kernel mappings (addresses above 0xC0000000 or whatever
-                 * PAGE_OFFSET is set to) haven't changed.  But Linux calls
-                 * flush_tlb_user() for both user and kernel mappings unless
-                 * the Page Global Enable (PGE) feature bit is set. */
-                *edx |= 0x00002000;
-                break;
-        case 0x80000000:
-                /* Futureproof this a little: if they ask how much extended
-                 * processor information there is, limit it to known fields. */
-                if (*eax > 0x80000008)
-                        *eax = 0x80000008;
-                break;
-        }
-}
-
-/* Intel has four control registers, imaginatively named cr0, cr2, cr3 and cr4.
- * I assume there's a cr1, but it hasn't bothered us yet, so we'll not bother
- * it.  The Host needs to know when the Guest wants to change them, so we have
- * a whole series of functions like read_cr0() and write_cr0().
- *
- * We start with CR0.  CR0 allows you to turn on and off all kinds of basic
- * features, but Linux only really cares about one: the horrifically-named Task
- * Switched (TS) bit at bit 3 (ie. 8)
- *
- * What does the TS bit do?  Well, it causes the CPU to trap (interrupt 7) if
- * the floating point unit is used.  Which allows us to restore FPU state
- * lazily after a task switch, and Linux uses that gratefully, but wouldn't a
- * name like "FPUTRAP bit" be a little less cryptic?
- *
- * We store cr0 (and cr3) locally, because the Host never changes it.  The
- * Guest sometimes wants to read it and we'd prefer not to bother the Host
- * unnecessarily. */
-static unsigned long current_cr0, current_cr3;
-static void lguest_write_cr0(unsigned long val)
-{
-        /* 8 == TS bit. */
-        lazy_hcall(LHCALL_TS, val & 8, 0, 0);
-        current_cr0 = val;
-}
-
-static unsigned long lguest_read_cr0(void)
-{
-        return current_cr0;
-}
-
-/* Intel provided a special instruction to clear the TS bit for people too cool
- * to use write_cr0() to do it.  This "clts" instruction is faster, because all
- * the vowels have been optimized out. */
-static void lguest_clts(void)
-{
-        lazy_hcall(LHCALL_TS, 0, 0, 0);
-        current_cr0 &= ~8U;
-}
-
-/* CR2 is the virtual address of the last page fault, which the Guest only ever
- * reads.  The Host kindly writes this into our "struct lguest_data", so we
- * just read it out of there. */
-static unsigned long lguest_read_cr2(void)
-{
-        return lguest_data.cr2;
-}
-
-/* CR3 is the current toplevel pagetable page: the principle is the same as
- * cr0.  Keep a local copy, and tell the Host when it changes. */
-static void lguest_write_cr3(unsigned long cr3)
-{
-        lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
-        current_cr3 = cr3;
-}
-
-static unsigned long lguest_read_cr3(void)
-{
-        return current_cr3;
-}
-
-/* CR4 is used to enable and disable PGE, but we don't care. */
-static unsigned long lguest_read_cr4(void)
-{
-        return 0;
-}
-
-static void lguest_write_cr4(unsigned long val)
-{
-}
-
-/*
- * Page Table Handling.
- *
- * Now would be a good time to take a rest and grab a coffee or similarly
- * relaxing stimulant.  The easy parts are behind us, and the trek gradually
- * winds uphill from here.
- *
- * Quick refresher: memory is divided into "pages" of 4096 bytes each.  The CPU
- * maps virtual addresses to physical addresses using "page tables".  We could
- * use one huge index of 1 million entries: each address is 4 bytes, so that's
- * 1024 pages just to hold the page tables.   But since most virtual addresses
- * are unused, we use a two level index which saves space.  The CR3 register
- * contains the physical address of the top level "page directory" page, which
- * contains physical addresses of up to 1024 second-level pages.  Each of these
- * second level pages contains up to 1024 physical addresses of actual pages,
- * or Page Table Entries (PTEs).
- *
- * Here's a diagram, where arrows indicate physical addresses:
- *
- * CR3 ---> +---------+
- *          |      --------->+---------+
- *          |         |      | PADDR1  |
- *        Top-level   |      | PADDR2  |
- *        (PMD) page  |      |         |
- *          |         |    Lower-level |
- *          |         |    (PTE) page  |
- *          |         |      |         |
- *            ....               ....
- *
- * So to convert a virtual address to a physical address, we look up the top
- * level, which points us to the second level, which gives us the physical
- * address of that page.  If the top level entry was not present, or the second
- * level entry was not present, then the virtual address is invalid (we
- * say "the page was not mapped").
- *
- * Put another way, a 32-bit virtual address is divided up like so:
- *
- *  1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
- * |<---- 10 bits ---->|<---- 10 bits ---->|<------ 12 bits ------>|
- *    Index into top     Index into second      Offset within page
- *  page directory page    pagetable page
- *
- * The kernel spends a lot of time changing both the top-level page directory
- * and lower-level pagetable pages.  The Guest doesn't know physical addresses,
- * so while it maintains these page tables exactly like normal, it also needs
- * to keep the Host informed whenever it makes a change: the Host will create
- * the real page tables based on the Guests'.
- */
-
-/* The Guest calls this to set a second-level entry (pte), ie. to map a page
- * into a process' address space.  We set the entry then tell the Host the
- * toplevel and address this corresponds to.  The Guest uses one pagetable per
- * process, so we need to tell the Host which one we're changing (mm->pgd). */
-static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
-                              pte_t *ptep, pte_t pteval)
-{
-        *ptep = pteval;
-        lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, pteval.pte_low);
-}
-
-/* The Guest calls this to set a top-level entry.  Again, we set the entry then
- * tell the Host which top-level page we changed, and the index of the entry we
- * changed. */
-static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
-{
-        *pmdp = pmdval;
-        lazy_hcall(LHCALL_SET_PMD, __pa(pmdp)&PAGE_MASK,
-                   (__pa(pmdp)&(PAGE_SIZE-1))/4, 0);
-}
-
-/* There are a couple of legacy places where the kernel sets a PTE, but we
- * don't know the top level any more.  This is useless for us, since we don't
- * know which pagetable is changing or what address, so we just tell the Host
- * to forget all of them.  Fortunately, this is very rare.
- *
- * ... except in early boot when the kernel sets up the initial pagetables,
- * which makes booting astonishingly slow.  So we don't even tell the Host
- * anything changed until we've done the first page table switch.
- */
-static void lguest_set_pte(pte_t *ptep, pte_t pteval)
-{
-        *ptep = pteval;
-        /* Don't bother with hypercall before initial setup. */
-        if (current_cr3)
-                lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
-}
-
-/* Unfortunately for Lguest, the pv_mmu_ops for page tables were based on
- * native page table operations.  On native hardware you can set a new page
- * table entry whenever you want, but if you want to remove one you have to do
- * a TLB flush (a TLB is a little cache of page table entries kept by the CPU).
- *
- * So the lguest_set_pte_at() and lguest_set_pmd() functions above are only
- * called when a valid entry is written, not when it's removed (ie. marked not
- * present).  Instead, this is where we come when the Guest wants to remove a
- * page table entry: we tell the Host to set that entry to 0 (ie. the present
- * bit is zero). */
-static void lguest_flush_tlb_single(unsigned long addr)
-{
-        /* Simply set it to zero: if it was not, it will fault back in. */
-        lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0);
-}
-
-/* This is what happens after the Guest has removed a large number of entries.
- * This tells the Host that any of the page table entries for userspace might
- * have changed, ie. virtual addresses below PAGE_OFFSET. */
-static void lguest_flush_tlb_user(void)
-{
-        lazy_hcall(LHCALL_FLUSH_TLB, 0, 0, 0);
-}
-
-/* This is called when the kernel page tables have changed.  That's not very
- * common (unless the Guest is using highmem, which makes the Guest extremely
- * slow), so it's worth separating this from the user flushing above. */
-static void lguest_flush_tlb_kernel(void)
-{
-        lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
-}
-
-/*
- * The Unadvanced Programmable Interrupt Controller.
- *
- * This is an attempt to implement the simplest possible interrupt controller.
- * I spent some time looking though routines like set_irq_chip_and_handler,
- * set_irq_chip_and_handler_name, set_irq_chip_data and set_phasers_to_stun and
- * I *think* this is as simple as it gets.
- *
- * We can tell the Host what interrupts we want blocked ready for using the
- * lguest_data.interrupts bitmap, so disabling (aka "masking") them is as
- * simple as setting a bit.  We don't actually "ack" interrupts as such, we
- * just mask and unmask them.  I wonder if we should be cleverer?
- */
-static void disable_lguest_irq(unsigned int irq)
-{
-        set_bit(irq, lguest_data.blocked_interrupts);
-}
-
-static void enable_lguest_irq(unsigned int irq)
-{
-        clear_bit(irq, lguest_data.blocked_interrupts);
-}
-
-/* This structure describes the lguest IRQ controller. */
-static struct irq_chip lguest_irq_controller = {
-        .name           = "lguest",
-        .mask           = disable_lguest_irq,
-        .mask_ack       = disable_lguest_irq,
-        .unmask         = enable_lguest_irq,
-};
-
-/* This sets up the Interrupt Descriptor Table (IDT) entry for each hardware
- * interrupt (except 128, which is used for system calls), and then tells the
- * Linux infrastructure that each interrupt is controlled by our level-based
- * lguest interrupt controller. */
-static void __init lguest_init_IRQ(void)
-{
-        unsigned int i;
-
-        for (i = 0; i < LGUEST_IRQS; i++) {
-                int vector = FIRST_EXTERNAL_VECTOR + i;
-                if (vector != SYSCALL_VECTOR) {
-                        set_intr_gate(vector, interrupt[i]);
-                        set_irq_chip_and_handler(i, &lguest_irq_controller,
-                                                 handle_level_irq);
-                }
-        }
-        /* This call is required to set up for 4k stacks, where we have
-         * separate stacks for hard and soft interrupts. */
-        irq_ctx_init(smp_processor_id());
-}
-
-/*
- * Time.
- *
- * It would be far better for everyone if the Guest had its own clock, but
- * until then the Host gives us the time on every interrupt.
- */
-static unsigned long lguest_get_wallclock(void)
-{
-        return lguest_data.time.tv_sec;
-}
-
-static cycle_t lguest_clock_read(void)
-{
-        unsigned long sec, nsec;
-
-        /* If the Host tells the TSC speed, we can trust that. */
-        if (lguest_data.tsc_khz)
-                return native_read_tsc();
-
-        /* If we can't use the TSC, we read the time value written by the Host.
-         * Since it's in two parts (seconds and nanoseconds), we risk reading
-         * it just as it's changing from 99 & 0.999999999 to 100 and 0, and
-         * getting 99 and 0.  As Linux tends to come apart under the stress of
-         * time travel, we must be careful: */
-        do {
-                /* First we read the seconds part. */
-                sec = lguest_data.time.tv_sec;
-                /* This read memory barrier tells the compiler and the CPU that
-                 * this can't be reordered: we have to complete the above
-                 * before going on. */
-                rmb();
-                /* Now we read the nanoseconds part. */
-                nsec = lguest_data.time.tv_nsec;
-                /* Make sure we've done that. */
-                rmb();
-                /* Now if the seconds part has changed, try again. */
-        } while (unlikely(lguest_data.time.tv_sec != sec));
-
-        /* Our non-TSC clock is in real nanoseconds. */
-        return sec*1000000000ULL + nsec;
-}
-
-/* This is what we tell the kernel is our clocksource.  */
-static struct clocksource lguest_clock = {
-        .name           = "lguest",
-        .rating         = 400,
-        .read           = lguest_clock_read,
-        .mask           = CLOCKSOURCE_MASK(64),
-        .mult           = 1 << 22,
-        .shift          = 22,
-};
-
-/* The "scheduler clock" is just our real clock, adjusted to start at zero */
-static unsigned long long lguest_sched_clock(void)
-{
-        return cyc2ns(&lguest_clock, lguest_clock_read() - clock_base);
-}
-
-/* We also need a "struct clock_event_device": Linux asks us to set it to go
- * off some time in the future.  Actually, James Morris figured all this out, I
- * just applied the patch. */
-static int lguest_clockevent_set_next_event(unsigned long delta,
-                                           struct clock_event_device *evt)
-{
-        if (delta < LG_CLOCK_MIN_DELTA) {
-                if (printk_ratelimit())
-                        printk(KERN_DEBUG "%s: small delta %lu ns\n",
-                               __FUNCTION__, delta);
-                return -ETIME;
-        }
-        hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0);
-        return 0;
-}
-
-static void lguest_clockevent_set_mode(enum clock_event_mode mode,
-                                      struct clock_event_device *evt)
-{
-        switch (mode) {
-        case CLOCK_EVT_MODE_UNUSED:
-        case CLOCK_EVT_MODE_SHUTDOWN:
-                /* A 0 argument shuts the clock down. */
-                hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0);
-                break;
-        case CLOCK_EVT_MODE_ONESHOT:
-                /* This is what we expect. */
-                break;
-        case CLOCK_EVT_MODE_PERIODIC:
-                BUG();
-        case CLOCK_EVT_MODE_RESUME:
-                break;
-        }
-}
-
-/* This describes our primitive timer chip. */
-static struct clock_event_device lguest_clockevent = {
-        .name                   = "lguest",
-        .features               = CLOCK_EVT_FEAT_ONESHOT,
-        .set_next_event         = lguest_clockevent_set_next_event,
-        .set_mode               = lguest_clockevent_set_mode,
-        .rating                 = INT_MAX,
-        .mult                   = 1,
-        .shift                  = 0,
-        .min_delta_ns           = LG_CLOCK_MIN_DELTA,
-        .max_delta_ns           = LG_CLOCK_MAX_DELTA,
-};
-
-/* This is the Guest timer interrupt handler (hardware interrupt 0).  We just
- * call the clockevent infrastructure and it does whatever needs doing. */
-static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
-{
-        unsigned long flags;
-
-        /* Don't interrupt us while this is running. */
-        local_irq_save(flags);
-        lguest_clockevent.event_handler(&lguest_clockevent);
-        local_irq_restore(flags);
-}
-
-/* At some point in the boot process, we get asked to set up our timing
- * infrastructure.  The kernel doesn't expect timer interrupts before this, but
- * we cleverly initialized the "blocked_interrupts" field of "struct
- * lguest_data" so that timer interrupts were blocked until now. */
-static void lguest_time_init(void)
-{
-        /* Set up the timer interrupt (0) to go to our simple timer routine */
-        set_irq_handler(0, lguest_time_irq);
-
-        /* Our clock structure look like arch/i386/kernel/tsc.c if we can use
-         * the TSC, otherwise it's a dumb nanosecond-resolution clock.  Either
-         * way, the "rating" is initialized so high that it's always chosen
-         * over any other clocksource. */
-        if (lguest_data.tsc_khz) {
-                lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
-                                                         lguest_clock.shift);
-                lguest_clock.flags = CLOCK_SOURCE_IS_CONTINUOUS;
-        }
-        clock_base = lguest_clock_read();
-        clocksource_register(&lguest_clock);
-
-        /* Now we've set up our clock, we can use it as the scheduler clock */
-        pv_time_ops.sched_clock = lguest_sched_clock;
-
-        /* We can't set cpumask in the initializer: damn C limitations!  Set it
-         * here and register our timer device. */
-        lguest_clockevent.cpumask = cpumask_of_cpu(0);
-        clockevents_register_device(&lguest_clockevent);
-
-        /* Finally, we unblock the timer interrupt. */
-        enable_lguest_irq(0);
-}
-
-/*
- * Miscellaneous bits and pieces.
- *
- * Here is an oddball collection of functions which the Guest needs for things
- * to work.  They're pretty simple.
- */
-
-/* The Guest needs to tell the host what stack it expects traps to use.  For
- * native hardware, this is part of the Task State Segment mentioned above in
- * lguest_load_tr_desc(), but to help hypervisors there's this special call.
- *
- * We tell the Host the segment we want to use (__KERNEL_DS is the kernel data
- * segment), the privilege level (we're privilege level 1, the Host is 0 and
- * will not tolerate us trying to use that), the stack pointer, and the number
- * of pages in the stack. */
-static void lguest_load_esp0(struct tss_struct *tss,
-                                     struct thread_struct *thread)
-{
-        lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->esp0,
-                   THREAD_SIZE/PAGE_SIZE);
-}
-
-/* Let's just say, I wouldn't do debugging under a Guest. */
-static void lguest_set_debugreg(int regno, unsigned long value)
-{
-        /* FIXME: Implement */
-}
-
-/* There are times when the kernel wants to make sure that no memory writes are
- * caught in the cache (that they've all reached real hardware devices).  This
- * doesn't matter for the Guest which has virtual hardware.
- *
- * On the Pentium 4 and above, cpuid() indicates that the Cache Line Flush
- * (clflush) instruction is available and the kernel uses that.  Otherwise, it
- * uses the older "Write Back and Invalidate Cache" (wbinvd) instruction.
- * Unlike clflush, wbinvd can only be run at privilege level 0.  So we can
- * ignore clflush, but replace wbinvd.
- */
-static void lguest_wbinvd(void)
-{
-}
-
-/* If the Guest expects to have an Advanced Programmable Interrupt Controller,
- * we play dumb by ignoring writes and returning 0 for reads.  So it's no
- * longer Programmable nor Controlling anything, and I don't think 8 lines of
- * code qualifies for Advanced.  It will also never interrupt anything.  It
- * does, however, allow us to get through the Linux boot code. */
-#ifdef CONFIG_X86_LOCAL_APIC
-static void lguest_apic_write(unsigned long reg, unsigned long v)
-{
-}
-
-static unsigned long lguest_apic_read(unsigned long reg)
-{
-        return 0;
-}
-#endif
-
-/* STOP!  Until an interrupt comes in. */
-static void lguest_safe_halt(void)
-{
-        hcall(LHCALL_HALT, 0, 0, 0);
-}
-
-/* Perhaps CRASH isn't the best name for this hypercall, but we use it to get a
- * message out when we're crashing as well as elegant termination like powering
- * off.
- *
- * Note that the Host always prefers that the Guest speak in physical addresses
- * rather than virtual addresses, so we use __pa() here. */
-static void lguest_power_off(void)
-{
-        hcall(LHCALL_CRASH, __pa("Power down"), 0, 0);
-}
-
-/*
- * Panicing.
- *
- * Don't.  But if you did, this is what happens.
- */
-static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
-{
-        hcall(LHCALL_CRASH, __pa(p), 0, 0);
-        /* The hcall won't return, but to keep gcc happy, we're "done". */
-        return NOTIFY_DONE;
-}
-
-static struct notifier_block paniced = {
-        .notifier_call = lguest_panic
-};
-
-/* Setting up memory is fairly easy. */
-static __init char *lguest_memory_setup(void)
-{
-        /* We do this here and not earlier because lockcheck barfs if we do it
-         * before start_kernel() */
-        atomic_notifier_chain_register(&panic_notifier_list, &paniced);
-
-        /* The Linux bootloader header contains an "e820" memory map: the
-         * Launcher populated the first entry with our memory limit. */
-        add_memory_region(boot_params.e820_map[0].addr,
-                          boot_params.e820_map[0].size,
-                          boot_params.e820_map[0].type);
-
-        /* This string is for the boot messages. */
-        return "LGUEST";
-}
-
-/*G:050
- * Patching (Powerfully Placating Performance Pedants)
- *
- * We have already seen that pv_ops structures let us replace simple
- * native instructions with calls to the appropriate back end all throughout
- * the kernel.  This allows the same kernel to run as a Guest and as a native
- * kernel, but it's slow because of all the indirect branches.
- *
- * Remember that David Wheeler quote about "Any problem in computer science can
- * be solved with another layer of indirection"?  The rest of that quote is
- * "... But that usually will create another problem."  This is the first of
- * those problems.
- *
- * Our current solution is to allow the paravirt back end to optionally patch
- * over the indirect calls to replace them with something more efficient.  We
- * patch the four most commonly called functions: disable interrupts, enable
- * interrupts, restore interrupts and save interrupts.  We usually have 10
- * bytes to patch into: the Guest versions of these operations are small enough
- * that we can fit comfortably.
- *
- * First we need assembly templates of each of the patchable Guest operations,
- * and these are in lguest_asm.S. */
-
-/*G:060 We construct a table from the assembler templates: */
-static const struct lguest_insns
-{
-        const char *start, *end;
-} lguest_insns[] = {
-        [PARAVIRT_PATCH(pv_irq_ops.irq_disable)] = { lgstart_cli, lgend_cli },
-        [PARAVIRT_PATCH(pv_irq_ops.irq_enable)] = { lgstart_sti, lgend_sti },
-        [PARAVIRT_PATCH(pv_irq_ops.restore_fl)] = { lgstart_popf, lgend_popf },
-        [PARAVIRT_PATCH(pv_irq_ops.save_fl)] = { lgstart_pushf, lgend_pushf },
-};
-
-/* Now our patch routine is fairly simple (based on the native one in
- * paravirt.c).  If we have a replacement, we copy it in and return how much of
- * the available space we used. */
-static unsigned lguest_patch(u8 type, u16 clobber, void *ibuf,
-                             unsigned long addr, unsigned len)
-{
-        unsigned int insn_len;
-
-        /* Don't do anything special if we don't have a replacement */
-        if (type >= ARRAY_SIZE(lguest_insns) || !lguest_insns[type].start)
-                return paravirt_patch_default(type, clobber, ibuf, addr, len);
-
-        insn_len = lguest_insns[type].end - lguest_insns[type].start;
-
-        /* Similarly if we can't fit replacement (shouldn't happen, but let's
-         * be thorough). */
-        if (len < insn_len)
-                return paravirt_patch_default(type, clobber, ibuf, addr, len);
-
-        /* Copy in our instructions. */
-        memcpy(ibuf, lguest_insns[type].start, insn_len);
-        return insn_len;
-}
-
-/*G:030 Once we get to lguest_init(), we know we're a Guest.  The pv_ops
- * structures in the kernel provide points for (almost) every routine we have
- * to override to avoid privileged instructions. */
-__init void lguest_init(void *boot)
-{
-        /* Copy boot parameters first: the Launcher put the physical location
-         * in %esi, and head.S converted that to a virtual address and handed
-         * it to us.  We use "__memcpy" because "memcpy" sometimes tries to do
-         * tricky things to go faster, and we're not ready for that. */
-        __memcpy(&boot_params, boot, PARAM_SIZE);
-        /* The boot parameters also tell us where the command-line is: save
-         * that, too. */
-        __memcpy(boot_command_line, __va(boot_params.hdr.cmd_line_ptr),
-               COMMAND_LINE_SIZE);
-
-        /* We're under lguest, paravirt is enabled, and we're running at
-         * privilege level 1, not 0 as normal. */
-        pv_info.name = "lguest";
-        pv_info.paravirt_enabled = 1;
-        pv_info.kernel_rpl = 1;
-
-        /* We set up all the lguest overrides for sensitive operations.  These
-         * are detailed with the operations themselves. */
-
-        /* interrupt-related operations */
-        pv_irq_ops.init_IRQ = lguest_init_IRQ;
-        pv_irq_ops.save_fl = save_fl;
-        pv_irq_ops.restore_fl = restore_fl;
-        pv_irq_ops.irq_disable = irq_disable;
-        pv_irq_ops.irq_enable = irq_enable;
-        pv_irq_ops.safe_halt = lguest_safe_halt;
-
-        /* init-time operations */
-        pv_init_ops.memory_setup = lguest_memory_setup;
-        pv_init_ops.patch = lguest_patch;
-
-        /* Intercepts of various cpu instructions */
-        pv_cpu_ops.load_gdt = lguest_load_gdt;
-        pv_cpu_ops.cpuid = lguest_cpuid;
-        pv_cpu_ops.load_idt = lguest_load_idt;
-        pv_cpu_ops.iret = lguest_iret;
-        pv_cpu_ops.load_esp0 = lguest_load_esp0;
-        pv_cpu_ops.load_tr_desc = lguest_load_tr_desc;
-        pv_cpu_ops.set_ldt = lguest_set_ldt;
-        pv_cpu_ops.load_tls = lguest_load_tls;
-        pv_cpu_ops.set_debugreg = lguest_set_debugreg;
-        pv_cpu_ops.clts = lguest_clts;
-        pv_cpu_ops.read_cr0 = lguest_read_cr0;
-        pv_cpu_ops.write_cr0 = lguest_write_cr0;
-        pv_cpu_ops.read_cr4 = lguest_read_cr4;
-        pv_cpu_ops.write_cr4 = lguest_write_cr4;
-        pv_cpu_ops.write_gdt_entry = lguest_write_gdt_entry;
-        pv_cpu_ops.write_idt_entry = lguest_write_idt_entry;
-        pv_cpu_ops.wbinvd = lguest_wbinvd;
-        pv_cpu_ops.lazy_mode.enter = paravirt_enter_lazy_cpu;
-        pv_cpu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
-
-        /* pagetable management */
-        pv_mmu_ops.write_cr3 = lguest_write_cr3;
-        pv_mmu_ops.flush_tlb_user = lguest_flush_tlb_user;
-        pv_mmu_ops.flush_tlb_single = lguest_flush_tlb_single;
-        pv_mmu_ops.flush_tlb_kernel = lguest_flush_tlb_kernel;
-        pv_mmu_ops.set_pte = lguest_set_pte;
-        pv_mmu_ops.set_pte_at = lguest_set_pte_at;
-        pv_mmu_ops.set_pmd = lguest_set_pmd;
-        pv_mmu_ops.read_cr2 = lguest_read_cr2;
-        pv_mmu_ops.read_cr3 = lguest_read_cr3;
-        pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu;
-        pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
-
-#ifdef CONFIG_X86_LOCAL_APIC
-        /* apic read/write intercepts */
-        pv_apic_ops.apic_write = lguest_apic_write;
-        pv_apic_ops.apic_write_atomic = lguest_apic_write;
-        pv_apic_ops.apic_read = lguest_apic_read;
-#endif
-
-        /* time operations */
-        pv_time_ops.get_wallclock = lguest_get_wallclock;
-        pv_time_ops.time_init = lguest_time_init;
-
-        /* Now is a good time to look at the implementations of these functions
-         * before returning to the rest of lguest_init(). */
-
-        /*G:070 Now we've seen all the paravirt_ops, we return to
-         * lguest_init() where the rest of the fairly chaotic boot setup
-         * occurs.
-         *
-         * The Host expects our first hypercall to tell it where our "struct
-         * lguest_data" is, so we do that first. */
-        hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
-
-        /* The native boot code sets up initial page tables immediately after
-         * the kernel itself, and sets init_pg_tables_end so they're not
-         * clobbered.  The Launcher places our initial pagetables somewhere at
-         * the top of our physical memory, so we don't need extra space: set
-         * init_pg_tables_end to the end of the kernel. */
-        init_pg_tables_end = __pa(pg0);
-
-        /* Load the %fs segment register (the per-cpu segment register) with
-         * the normal data segment to get through booting. */
-        asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
-
-        /* Clear the part of the kernel data which is expected to be zero.
-         * Normally it will be anyway, but if we're loading from a bzImage with
-         * CONFIG_RELOCATALE=y, the relocations will be sitting here. */
-        memset(__bss_start, 0, __bss_stop - __bss_start);
-
-        /* The Host uses the top of the Guest's virtual address space for the
-         * Host<->Guest Switcher, and it tells us how much it needs in
-         * lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */
-        reserve_top_address(lguest_data.reserve_mem);
-
-        /* If we don't initialize the lock dependency checker now, it crashes
-         * paravirt_disable_iospace. */
-        lockdep_init();
-
-        /* The IDE code spends about 3 seconds probing for disks: if we reserve
-         * all the I/O ports up front it can't get them and so doesn't probe.
-         * Other device drivers are similar (but less severe).  This cuts the
-         * kernel boot time on my machine from 4.1 seconds to 0.45 seconds. */
-        paravirt_disable_iospace();
-
-        /* This is messy CPU setup stuff which the native boot code does before
-         * start_kernel, so we have to do, too: */
-        cpu_detect(&new_cpu_data);
-        /* head.S usually sets up the first capability word, so do it here. */
-        new_cpu_data.x86_capability[0] = cpuid_edx(1);
-
-        /* Math is always hard! */
-        new_cpu_data.hard_math = 1;
-
-#ifdef CONFIG_X86_MCE
-        mce_disabled = 1;
-#endif
-#ifdef CONFIG_ACPI
-        acpi_disabled = 1;
-        acpi_ht = 0;
-#endif
-
-        /* We set the perferred console to "hvc".  This is the "hypervisor
-         * virtual console" driver written by the PowerPC people, which we also
-         * adapted for lguest's use. */
-        add_preferred_console("hvc", 0, NULL);
-
-        /* Last of all, we set the power management poweroff hook to point to
-         * the Guest routine to power off. */
-        pm_power_off = lguest_power_off;
-
-        /* Now we're set up, call start_kernel() in init/main.c and we proceed
-         * to boot as normal.  It never returns. */
-        start_kernel();
-}
-/*
- * This marks the end of stage II of our journey, The Guest.
- *
- * It is now time for us to explore the nooks and crannies of the three Guest
- * devices and complete our understanding of the Guest in "make Drivers".
- */
diff --git a/drivers/lguest/lguest_asm.S b/drivers/lguest/lguest_asm.S
deleted file mode 100644
index 1ddcd5cd20f6..000000000000
--- a/drivers/lguest/lguest_asm.S
+++ /dev/null
@@ -1,93 +0,0 @@
-#include <linux/linkage.h>
-#include <linux/lguest.h>
-#include <asm/asm-offsets.h>
-#include <asm/thread_info.h>
-#include <asm/processor-flags.h>
-
-/*G:020 This is where we begin: we have a magic signature which the launcher
- * looks for.  The plan is that the Linux boot protocol will be extended with a
- * "platform type" field which will guide us here from the normal entry point,
- * but for the moment this suffices.  The normal boot code uses %esi for the
- * boot header, so we do too.  We convert it to a virtual address by adding
- * PAGE_OFFSET, and hand it to lguest_init() as its argument (ie. %eax).
- *
- * The .section line puts this code in .init.text so it will be discarded after
- * boot. */
-.section .init.text, "ax", @progbits
-.ascii "GenuineLguest"
-        /* Set up initial stack. */
-        movl $(init_thread_union+THREAD_SIZE),%esp
-        movl %esi, %eax
-        addl $__PAGE_OFFSET, %eax
-        jmp lguest_init
-
-/*G:055 We create a macro which puts the assembler code between lgstart_ and
- * lgend_ markers.  These templates are put in the .text section: they can't be
- * discarded after boot as we may need to patch modules, too. */
-.text
-#define LGUEST_PATCH(name, insns...)                    \
-        lgstart_##name: insns; lgend_##name:;           \
-        .globl lgstart_##name; .globl lgend_##name
-
-LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled)
-LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled)
-LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled)
-LGUEST_PATCH(pushf, movl lguest_data+LGUEST_DATA_irq_enabled, %eax)
-/*:*/
-
-/* These demark the EIP range where host should never deliver interrupts. */
-.global lguest_noirq_start
-.global lguest_noirq_end
-
-/*M:004 When the Host reflects a trap or injects an interrupt into the Guest,
- * it sets the eflags interrupt bit on the stack based on
- * lguest_data.irq_enabled, so the Guest iret logic does the right thing when
- * restoring it.  However, when the Host sets the Guest up for direct traps,
- * such as system calls, the processor is the one to push eflags onto the
- * stack, and the interrupt bit will be 1 (in reality, interrupts are always
- * enabled in the Guest).
- *
- * This turns out to be harmless: the only trap which should happen under Linux
- * with interrupts disabled is Page Fault (due to our lazy mapping of vmalloc
- * regions), which has to be reflected through the Host anyway.  If another
- * trap *does* go off when interrupts are disabled, the Guest will panic, and
- * we'll never get to this iret! :*/
-
-/*G:045 There is one final paravirt_op that the Guest implements, and glancing
- * at it you can see why I left it to last.  It's *cool*!  It's in *assembler*!
- *
- * The "iret" instruction is used to return from an interrupt or trap.  The
- * stack looks like this:
- *   old address
- *   old code segment & privilege level
- *   old processor flags ("eflags")
- *
- * The "iret" instruction pops those values off the stack and restores them all
- * at once.  The only problem is that eflags includes the Interrupt Flag which
- * the Guest can't change: the CPU will simply ignore it when we do an "iret".
- * So we have to copy eflags from the stack to lguest_data.irq_enabled before
- * we do the "iret".
- *
- * There are two problems with this: firstly, we need to use a register to do
- * the copy and secondly, the whole thing needs to be atomic.  The first
- * problem is easy to solve: push %eax on the stack so we can use it, and then
- * restore it at the end just before the real "iret".
- *
- * The second is harder: copying eflags to lguest_data.irq_enabled will turn
- * interrupts on before we're finished, so we could be interrupted before we
- * return to userspace or wherever.  Our solution to this is to surround the
- * code with lguest_noirq_start: and lguest_noirq_end: labels.  We tell the
- * Host that it is *never* to interrupt us there, even if interrupts seem to be
- * enabled. */
-ENTRY(lguest_iret)
-        pushl   %eax
-        movl    12(%esp), %eax
-lguest_noirq_start:
-        /* Note the %ss: segment prefix here.  Normal data accesses use the
-         * "ds" segment, but that will have already been restored for whatever
-         * we're returning to (such as userspace): we can't trust it.  The %ss:
-         * prefix makes sure we use the stack segment, which is still valid. */
-        movl    %eax,%ss:lguest_data+LGUEST_DATA_irq_enabled
-        popl    %eax
-        iret
-lguest_noirq_end:
diff --git a/drivers/lguest/lguest_bus.c b/drivers/lguest/lguest_bus.c
deleted file mode 100644
index 57329788f8a7..000000000000
--- a/drivers/lguest/lguest_bus.c
+++ /dev/null
@@ -1,218 +0,0 @@
-/*P:050 Lguest guests use a very simple bus for devices.  It's a simple array
- * of device descriptors contained just above the top of normal memory.  The
- * lguest bus is 80% tedious boilerplate code. :*/
-#include <linux/init.h>
-#include <linux/bootmem.h>
-#include <linux/lguest_bus.h>
-#include <asm/io.h>
-#include <asm/paravirt.h>
-
-static ssize_t type_show(struct device *_dev,
-                         struct device_attribute *attr, char *buf)
-{
-        struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
-        return sprintf(buf, "%hu", lguest_devices[dev->index].type);
-}
-static ssize_t features_show(struct device *_dev,
-                             struct device_attribute *attr, char *buf)
-{
-        struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
-        return sprintf(buf, "%hx", lguest_devices[dev->index].features);
-}
-static ssize_t pfn_show(struct device *_dev,
-                         struct device_attribute *attr, char *buf)
-{
-        struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
-        return sprintf(buf, "%u", lguest_devices[dev->index].pfn);
-}
-static ssize_t status_show(struct device *_dev,
-                           struct device_attribute *attr, char *buf)
-{
-        struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
-        return sprintf(buf, "%hx", lguest_devices[dev->index].status);
-}
-static ssize_t status_store(struct device *_dev, struct device_attribute *attr,
-                            const char *buf, size_t count)
-{
-        struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
-        if (sscanf(buf, "%hi", &lguest_devices[dev->index].status) != 1)
-                return -EINVAL;
-        return count;
-}
-static struct device_attribute lguest_dev_attrs[] = {
-        __ATTR_RO(type),
-        __ATTR_RO(features),
-        __ATTR_RO(pfn),
-        __ATTR(status, 0644, status_show, status_store),
-        __ATTR_NULL
-};
-
-/*D:130 The generic bus infrastructure requires a function which says whether a
- * device matches a driver.  For us, it is simple: "struct lguest_driver"
- * contains a "device_type" field which indicates what type of device it can
- * handle, so we just cast the args and compare: */
-static int lguest_dev_match(struct device *_dev, struct device_driver *_drv)
-{
-        struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
-        struct lguest_driver *drv = container_of(_drv,struct lguest_driver,drv);
-
-        return (drv->device_type == lguest_devices[dev->index].type);
-}
-/*:*/
-
-struct lguest_bus {
-        struct bus_type bus;
-        struct device dev;
-};
-
-static struct lguest_bus lguest_bus = {
-        .bus = {
-                .name  = "lguest",
-                .match = lguest_dev_match,
-                .dev_attrs = lguest_dev_attrs,
-        },
-        .dev = {
-                .parent = NULL,
-                .bus_id = "lguest",
-        }
-};
-
-/*D:140 This is the callback which occurs once the bus infrastructure matches
- * up a device and driver, ie. in response to add_lguest_device() calling
- * device_register(), or register_lguest_driver() calling driver_register().
- *
- * At the moment it's always the latter: the devices are added first, since
- * scan_devices() is called from a "core_initcall", and the drivers themselves
- * called later as a normal "initcall".  But it would work the other way too.
- *
- * So now we have the happy couple, we add the status bit to indicate that we
- * found a driver.  If the driver truly loves the device, it will return
- * happiness from its probe function (ok, perhaps this wasn't my greatest
- * analogy), and we set the final "driver ok" bit so the Host sees it's all
- * green. */
-static int lguest_dev_probe(struct device *_dev)
-{
-        int ret;
-        struct lguest_device*dev = container_of(_dev,struct lguest_device,dev);
-        struct lguest_driver*drv = container_of(dev->dev.driver,
-                                                struct lguest_driver, drv);
-
-        lguest_devices[dev->index].status |= LGUEST_DEVICE_S_DRIVER;
-        ret = drv->probe(dev);
-        if (ret == 0)
-                lguest_devices[dev->index].status |= LGUEST_DEVICE_S_DRIVER_OK;
-        return ret;
-}
-
-/* The last part of the bus infrastructure is the function lguest drivers use
- * to register themselves.  Firstly, we do nothing if there's no lguest bus
- * (ie. this is not a Guest), otherwise we fill in the embedded generic "struct
- * driver" fields and call the generic driver_register(). */
-int register_lguest_driver(struct lguest_driver *drv)
-{
-        if (!lguest_devices)
-                return 0;
-
-        drv->drv.bus = &lguest_bus.bus;
-        drv->drv.name = drv->name;
-        drv->drv.owner = drv->owner;
-        drv->drv.probe = lguest_dev_probe;
-
-        return driver_register(&drv->drv);
-}
-
-/* At the moment we build all the drivers into the kernel because they're so
- * simple: 8144 bytes for all three of them as I type this.  And as the console
- * really needs to be built in, it's actually only 3527 bytes for the network
- * and block drivers.
- *
- * If they get complex it will make sense for them to be modularized, so we
- * need to explicitly export the symbol.
- *
- * I don't think non-GPL modules make sense, so it's a GPL-only export.
- */
-EXPORT_SYMBOL_GPL(register_lguest_driver);
-
-/*D:120 This is the core of the lguest bus: actually adding a new device.
- * It's a separate function because it's neater that way, and because an
- * earlier version of the code supported hotplug and unplug.  They were removed
- * early on because they were never used.
- *
- * As Andrew Tridgell says, "Untested code is buggy code".
- *
- * It's worth reading this carefully: we start with an index into the array of
- * "struct lguest_device_desc"s indicating the device which is new: */
-static void add_lguest_device(unsigned int index)
-{
-        struct lguest_device *new;
-
-        /* Each "struct lguest_device_desc" has a "status" field, which the
-         * Guest updates as the device is probed.  In the worst case, the Host
-         * can look at these bits to tell what part of device setup failed,
-         * even if the console isn't available. */
-        lguest_devices[index].status |= LGUEST_DEVICE_S_ACKNOWLEDGE;
-        new = kmalloc(sizeof(struct lguest_device), GFP_KERNEL);
-        if (!new) {
-                printk(KERN_EMERG "Cannot allocate lguest device %u\n", index);
-                lguest_devices[index].status |= LGUEST_DEVICE_S_FAILED;
-                return;
-        }
-
-        /* The "struct lguest_device" setup is pretty straight-forward example
-         * code. */
-        new->index = index;
-        new->private = NULL;
-        memset(&new->dev, 0, sizeof(new->dev));
-        new->dev.parent = &lguest_bus.dev;
-        new->dev.bus = &lguest_bus.bus;
-        sprintf(new->dev.bus_id, "%u", index);
-
-        /* device_register() causes the bus infrastructure to look for a
-         * matching driver. */
-        if (device_register(&new->dev) != 0) {
-                printk(KERN_EMERG "Cannot register lguest device %u\n", index);
-                lguest_devices[index].status |= LGUEST_DEVICE_S_FAILED;
-                kfree(new);
-        }
-}
-
-/*D:110 scan_devices() simply iterates through the device array.  The type 0
- * is reserved to mean "no device", and anything else means we have found a
- * device: add it. */
-static void scan_devices(void)
-{
-        unsigned int i;
-
-        for (i = 0; i < LGUEST_MAX_DEVICES; i++)
-                if (lguest_devices[i].type)
-                        add_lguest_device(i);
-}
-
-/*D:100 Fairly early in boot, lguest_bus_init() is called to set up the lguest
- * bus.  We check that we are a Guest by checking paravirt_ops.name: there are
- * other ways of checking, but this seems most obvious to me.
- *
- * So we can access the array of "struct lguest_device_desc"s easily, we map
- * that memory and store the pointer in the global "lguest_devices".  Then we
- * register the bus with the core.  Doing two registrations seems clunky to me,
- * but it seems to be the correct sysfs incantation.
- *
- * Finally we call scan_devices() which adds all the devices found in the
- * "struct lguest_device_desc" array. */
-static int __init lguest_bus_init(void)
-{
-        if (strcmp(pv_info.name, "lguest") != 0)
-                return 0;
-
-        /* Devices are in a single page above top of "normal" mem */
-        lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);
-
-        if (bus_register(&lguest_bus.bus) != 0
-            || device_register(&lguest_bus.dev) != 0)
-                panic("lguest bus registration failed");
-
-        scan_devices();
-        return 0;
-}
-/* Do this after core stuff, before devices. */
-postcore_initcall(lguest_bus_init);
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
new file mode 100644
index 000000000000..71c64837b437
--- /dev/null
+++ b/drivers/lguest/lguest_device.c
@@ -0,0 +1,373 @@
+/*P:050 Lguest guests use a very simple method to describe devices.  It's a
+ * series of device descriptors contained just above the top of normal
+ * memory.
+ *
+ * We use the standard "virtio" device infrastructure, which provides us with a
+ * console, a network and a block driver.  Each one expects some configuration
+ * information and a "virtqueue" mechanism to send and receive data. :*/
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/lguest_launcher.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/interrupt.h>
+#include <linux/virtio_ring.h>
+#include <linux/err.h>
+#include <asm/io.h>
+#include <asm/paravirt.h>
+#include <asm/lguest_hcall.h>
+
+/* The pointer to our (page) of device descriptions. */
+static void *lguest_devices;
+
+/* Unique numbering for lguest devices. */
+static unsigned int dev_index;
+
+/* For Guests, device memory can be used as normal memory, so we cast away the
+ * __iomem to quieten sparse. */
+static inline void *lguest_map(unsigned long phys_addr, unsigned long pages)
+{
+        return (__force void *)ioremap(phys_addr, PAGE_SIZE*pages);
+}
+
+static inline void lguest_unmap(void *addr)
+{
+        iounmap((__force void __iomem *)addr);
+}
+
+/*D:100 Each lguest device is just a virtio device plus a pointer to its entry
+ * in the lguest_devices page. */
+struct lguest_device {
+        struct virtio_device vdev;
+
+        /* The entry in the lguest_devices page for this device. */
+        struct lguest_device_desc *desc;
+};
+
+/* Since the virtio infrastructure hands us a pointer to the virtio_device all
+ * the time, it helps to have a curt macro to get a pointer to the struct
+ * lguest_device it's enclosed in.  */
+#define to_lgdev(vdev) container_of(vdev, struct lguest_device, vdev)
+
+/*D:130
+ * Device configurations
+ *
+ * The configuration information for a device consists of a series of fields.
+ * The device will look for these fields during setup.
+ *
+ * For us these fields come immediately after that device's descriptor in the
+ * lguest_devices page.
+ *
+ * Each field starts with a "type" byte, a "length" byte, then that number of
+ * bytes of configuration information.  The device descriptor tells us the
+ * total configuration length so we know when we've reached the last field. */
+
+/* type + length bytes */
+#define FHDR_LEN 2
+
+/* This finds the first field of a given type for a device's configuration. */
+static void *lg_find(struct virtio_device *vdev, u8 type, unsigned int *len)
+{
+        struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+        int i;
+
+        for (i = 0; i < desc->config_len; i += FHDR_LEN + desc->config[i+1]) {
+                if (desc->config[i] == type) {
+                        /* Mark it used, so Host can know we looked at it, and
+                         * also so we won't find the same one twice. */
+                        desc->config[i] |= 0x80;
+                        /* Remember, the second byte is the length. */
+                        *len = desc->config[i+1];
+                        /* We return a pointer to the field header. */
+                        return desc->config + i;
+                }
+        }
+
+        /* Not found: return NULL for failure. */
+        return NULL;
+}
+
+/* Once they've found a field, getting a copy of it is easy. */
+static void lg_get(struct virtio_device *vdev, void *token,
+                   void *buf, unsigned len)
+{
+        /* Check they didn't ask for more than the length of the field! */
+        BUG_ON(len > ((u8 *)token)[1]);
+        memcpy(buf, token + FHDR_LEN, len);
+}
+
+/* Setting the contents is also trivial. */
+static void lg_set(struct virtio_device *vdev, void *token,
+                   const void *buf, unsigned len)
+{
+        BUG_ON(len > ((u8 *)token)[1]);
+        memcpy(token + FHDR_LEN, buf, len);
+}
+
+/* The operations to get and set the status word just access the status field
+ * of the device descriptor. */
+static u8 lg_get_status(struct virtio_device *vdev)
+{
+        return to_lgdev(vdev)->desc->status;
+}
+
+static void lg_set_status(struct virtio_device *vdev, u8 status)
+{
+        to_lgdev(vdev)->desc->status = status;
+}
+
+/*
+ * Virtqueues
+ *
+ * The other piece of infrastructure virtio needs is a "virtqueue": a way of
+ * the Guest device registering buffers for the other side to read from or
+ * write into (ie. send and receive buffers).  Each device can have multiple
+ * virtqueues: for example the console has one queue for sending and one for
+ * receiving.
+ *
+ * Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue
+ * already exists in virtio_ring.c.  We just need to connect it up.
+ *
+ * We start with the information we need to keep about each virtqueue.
+ */
+
+/*D:140 This is the information we remember about each virtqueue. */
+struct lguest_vq_info
+{
+        /* A copy of the information contained in the device config. */
+        struct lguest_vqconfig config;
+
+        /* The address where we mapped the virtio ring, so we can unmap it. */
+        void *pages;
+};
+
+/* When the virtio_ring code wants to prod the Host, it calls us here and we
+ * make a hypercall.  We hand the page number of the virtqueue so the Host
+ * knows which virtqueue we're talking about. */
+static void lg_notify(struct virtqueue *vq)
+{
+        /* We store our virtqueue information in the "priv" pointer of the
+         * virtqueue structure. */
+        struct lguest_vq_info *lvq = vq->priv;
+
+        hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0);
+}
+
+/* This routine finds the first virtqueue described in the configuration of
+ * this device and sets it up.
+ *
+ * This is kind of an ugly duckling.  It'd be nicer to have a standard
+ * representation of a virtqueue in the configuration space, but it seems that
+ * everyone wants to do it differently.  The KVM guys want the Guest to
+ * allocate its own pages and tell the Host where they are, but for lguest it's
+ * simpler for the Host to simply tell us where the pages are.
+ *
+ * So we provide devices with a "find virtqueue and set it up" function. */
+static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
+                                    bool (*callback)(struct virtqueue *vq))
+{
+        struct lguest_vq_info *lvq;
+        struct virtqueue *vq;
+        unsigned int len;
+        void *token;
+        int err;
+
+        /* Look for a field of the correct type to mark a virtqueue.  Note that
+         * if this succeeds, then the type will be changed so it won't be found
+         * again, and future lg_find_vq() calls will find the next
+         * virtqueue (if any). */
+        token = vdev->config->find(vdev, VIRTIO_CONFIG_F_VIRTQUEUE, &len);
+        if (!token)
+                return ERR_PTR(-ENOENT);
+
+        lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
+        if (!lvq)
+                return ERR_PTR(-ENOMEM);
+
+        /* Note: we could use a configuration space inside here, just like we
+         * do for the device.  This would allow expansion in future, because
+         * our configuration system is designed to be expansible.  But this is
+         * way easier. */
+        if (len != sizeof(lvq->config)) {
+                dev_err(&vdev->dev, "Unexpected virtio config len %u\n", len);
+                err = -EIO;
+                goto free_lvq;
+        }
+        /* Make a copy of the "struct lguest_vqconfig" field.  We need a copy
+         * because the config space might not be aligned correctly. */
+        vdev->config->get(vdev, token, &lvq->config, sizeof(lvq->config));
+
+        /* Figure out how many pages the ring will take, and map that memory */
+        lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
+                                DIV_ROUND_UP(vring_size(lvq->config.num),
+                                             PAGE_SIZE));
+        if (!lvq->pages) {
+                err = -ENOMEM;
+                goto free_lvq;
+        }
+
+        /* OK, tell virtio_ring.c to set up a virtqueue now we know its size
+         * and we've got a pointer to its pages. */
+        vq = vring_new_virtqueue(lvq->config.num, vdev, lvq->pages,
+                                 lg_notify, callback);
+        if (!vq) {
+                err = -ENOMEM;
+                goto unmap;
+        }
+
+        /* Tell the interrupt for this virtqueue to go to the virtio_ring
+         * interrupt handler. */
+        /* FIXME: We used to have a flag for the Host to tell us we could use
+         * the interrupt as a source of randomness: it'd be nice to have that
+         * back.. */
+        err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
+                          vdev->dev.bus_id, vq);
+        if (err)
+                goto destroy_vring;
+
+        /* Last of all we hook up our 'struct lguest_vq_info" to the
+         * virtqueue's priv pointer. */
+        vq->priv = lvq;
+        return vq;
+
+destroy_vring:
+        vring_del_virtqueue(vq);
+unmap:
+        lguest_unmap(lvq->pages);
+free_lvq:
+        kfree(lvq);
+        return ERR_PTR(err);
+}
+/*:*/
+
+/* Cleaning up a virtqueue is easy */
+static void lg_del_vq(struct virtqueue *vq)
+{
+        struct lguest_vq_info *lvq = vq->priv;
+
+        /* Tell virtio_ring.c to free the virtqueue. */
+        vring_del_virtqueue(vq);
+        /* Unmap the pages containing the ring. */
+        lguest_unmap(lvq->pages);
+        /* Free our own queue information. */
+        kfree(lvq);
+}
+
+/* The ops structure which hooks everything together. */
+static struct virtio_config_ops lguest_config_ops = {
+        .find = lg_find,
+        .get = lg_get,
+        .set = lg_set,
+        .get_status = lg_get_status,
+        .set_status = lg_set_status,
+        .find_vq = lg_find_vq,
+        .del_vq = lg_del_vq,
+};
+
+/* The root device for the lguest virtio devices.  This makes them appear as
+ * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2. */
+static struct device lguest_root = {
+        .parent = NULL,
+        .bus_id = "lguest",
+};
+
+/*D:120 This is the core of the lguest bus: actually adding a new device.
+ * It's a separate function because it's neater that way, and because an
+ * earlier version of the code supported hotplug and unplug.  They were removed
+ * early on because they were never used.
+ *
+ * As Andrew Tridgell says, "Untested code is buggy code".
+ *
+ * It's worth reading this carefully: we start with a pointer to the new device
+ * descriptor in the "lguest_devices" page. */
+static void add_lguest_device(struct lguest_device_desc *d)
+{
+        struct lguest_device *ldev;
+
+        ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
+        if (!ldev) {
+                printk(KERN_EMERG "Cannot allocate lguest dev %u\n",
+                       dev_index++);
+                return;
+        }
+
+        /* This devices' parent is the lguest/ dir. */
+        ldev->vdev.dev.parent = &lguest_root;
+        /* We have a unique device index thanks to the dev_index counter. */
+        ldev->vdev.index = dev_index++;
+        /* The device type comes straight from the descriptor.  There's also a
+         * device vendor field in the virtio_device struct, which we leave as
+         * 0. */
+        ldev->vdev.id.device = d->type;
+        /* We have a simple set of routines for querying the device's
+         * configuration information and setting its status. */
+        ldev->vdev.config = &lguest_config_ops;
+        /* And we remember the device's descriptor for lguest_config_ops. */
+        ldev->desc = d;
+
+        /* register_virtio_device() sets up the generic fields for the struct
+         * virtio_device and calls device_register().  This makes the bus
+         * infrastructure look for a matching driver. */
+        if (register_virtio_device(&ldev->vdev) != 0) {
+                printk(KERN_ERR "Failed to register lguest device %u\n",
+                       ldev->vdev.index);
+                kfree(ldev);
+        }
+}
+
+/*D:110 scan_devices() simply iterates through the device page.  The type 0 is
+ * reserved to mean "end of devices". */
+static void scan_devices(void)
+{
+        unsigned int i;
+        struct lguest_device_desc *d;
+
+        /* We start at the page beginning, and skip over each entry. */
+        for (i = 0; i < PAGE_SIZE; i += sizeof(*d) + d->config_len) {
+                d = lguest_devices + i;
+
+                /* Once we hit a zero, stop. */
+                if (d->type == 0)
+                        break;
+
+                add_lguest_device(d);
+        }
+}
+
+/*D:105 Fairly early in boot, lguest_devices_init() is called to set up the
+ * lguest device infrastructure.  We check that we are a Guest by checking
+ * pv_info.name: there are other ways of checking, but this seems most
+ * obvious to me.
+ *
+ * So we can access the "struct lguest_device_desc"s easily, we map that memory
+ * and store the pointer in the global "lguest_devices".  Then we register a
+ * root device from which all our devices will hang (this seems to be the
+ * correct sysfs incantation).
+ *
+ * Finally we call scan_devices() which adds all the devices found in the
+ * lguest_devices page. */
+static int __init lguest_devices_init(void)
+{
+        if (strcmp(pv_info.name, "lguest") != 0)
+                return 0;
+
+        if (device_register(&lguest_root) != 0)
+                panic("Could not register lguest root");
+
+        /* Devices are in a single page above top of "normal" mem */
+        lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);
+
+        scan_devices();
+        return 0;
+}
+/* We do this after core stuff, but before the drivers. */
+postcore_initcall(lguest_devices_init);
+
+/*D:150 At this point in the journey we used to now wade through the lguest
+ * devices themselves: net, block and console.  Since they're all now virtio
+ * devices rather than lguest-specific, I've decided to ignore them.  Mostly,
+ * they're kind of boring.  But this does mean you'll never experience the
+ * thrill of reading the forbidden love scene buried deep in the block driver.
+ *
+ * "make Launcher" beckons, where we answer questions like "Where do Guests
+ * come from?", and "What do you do when someone asks for optimization?". */
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 80d1b58c7698..ee405b38383d 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -1,73 +1,17 @@
 /*P:200 This contains all the /dev/lguest code, whereby the userspace launcher
  * controls and communicates with the Guest.  For example, the first write will
- * tell us the memory size, pagetable, entry point and kernel address offset.
- * A read will run the Guest until a signal is pending (-EINTR), or the Guest
- * does a DMA out to the Launcher.  Writes are also used to get a DMA buffer
- * registered by the Guest and to send the Guest an interrupt. :*/
+ * tell us the Guest's memory layout, pagetable, entry point and kernel address
+ * offset.  A read will run the Guest until something happens, such as a signal
+ * or the Guest doing a NOTIFY out to the Launcher. :*/
 #include <linux/uaccess.h>
 #include <linux/miscdevice.h>
 #include <linux/fs.h>
 #include "lg.h"
 
-/*L:030 setup_regs() doesn't really belong in this file, but it gives us an
- * early glimpse deeper into the Host so it's worth having here.
- *
- * Most of the Guest's registers are left alone: we used get_zeroed_page() to
- * allocate the structure, so they will be 0. */
-static void setup_regs(struct lguest_regs *regs, unsigned long start)
-{
-        /* There are four "segment" registers which the Guest needs to boot:
-         * The "code segment" register (cs) refers to the kernel code segment
-         * __KERNEL_CS, and the "data", "extra" and "stack" segment registers
-         * refer to the kernel data segment __KERNEL_DS.
-         *
-         * The privilege level is packed into the lower bits.  The Guest runs
-         * at privilege level 1 (GUEST_PL).*/
-        regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
-        regs->cs = __KERNEL_CS|GUEST_PL;
-
-        /* The "eflags" register contains miscellaneous flags.  Bit 1 (0x002)
-         * is supposed to always be "1".  Bit 9 (0x200) controls whether
-         * interrupts are enabled.  We always leave interrupts enabled while
-         * running the Guest. */
-        regs->eflags = 0x202;
-
-        /* The "Extended Instruction Pointer" register says where the Guest is
-         * running. */
-        regs->eip = start;
-
-        /* %esi points to our boot information, at physical address 0, so don't
-         * touch it. */
-}
-
-/*L:310 To send DMA into the Guest, the Launcher needs to be able to ask for a
- * DMA buffer.  This is done by writing LHREQ_GETDMA and the key to
- * /dev/lguest. */
-static long user_get_dma(struct lguest *lg, const u32 __user *input)
-{
-        unsigned long key, udma, irq;
-
-        /* Fetch the key they wrote to us. */
-        if (get_user(key, input) != 0)
-                return -EFAULT;
-        /* Look for a free Guest DMA buffer bound to that key. */
-        udma = get_dma_buffer(lg, key, &irq);
-        if (!udma)
-                return -ENOENT;
-
-        /* We need to tell the Launcher what interrupt the Guest expects after
-         * the buffer is filled.  We stash it in udma->used_len. */
-        lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
-
-        /* The (guest-physical) address of the DMA buffer is returned from
-         * the write(). */
-        return udma;
-}
-
 /*L:315 To force the Guest to stop running and return to the Launcher, the
  * Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest.  The
  * Launcher then writes LHREQ_BREAK and "0" to release the Waker. */
-static int break_guest_out(struct lguest *lg, const u32 __user *input)
+static int break_guest_out(struct lguest *lg, const unsigned long __user *input)
 {
         unsigned long on;
 
@@ -90,9 +34,9 @@ static int break_guest_out(struct lguest *lg, const u32 __user *input)
 
 /*L:050 Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
  * number to /dev/lguest. */
-static int user_send_irq(struct lguest *lg, const u32 __user *input)
+static int user_send_irq(struct lguest *lg, const unsigned long __user *input)
 {
-        u32 irq;
+        unsigned long irq;
 
         if (get_user(irq, input) != 0)
                 return -EFAULT;
@@ -133,17 +77,19 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
                 return len;
         }
 
-        /* If we returned from read() last time because the Guest sent DMA,
+        /* If we returned from read() last time because the Guest notified,
          * clear the flag. */
-        if (lg->dma_is_pending)
-                lg->dma_is_pending = 0;
+        if (lg->pending_notify)
+                lg->pending_notify = 0;
 
         /* Run the Guest until something interesting happens. */
         return run_guest(lg, (unsigned long __user *)user);
 }
 
-/*L:020 The initialization write supplies 4 32-bit values (in addition to the
- * 32-bit LHREQ_INITIALIZE value).  These are:
+/*L:020 The initialization write supplies 4 pointer sized (32 or 64 bit)
+ * values (in addition to the LHREQ_INITIALIZE value).  These are:
+ *
+ * base: The start of the Guest-physical memory inside the Launcher memory.
  *
  * pfnlimit: The highest (Guest-physical) page number the Guest should be
  * allowed to access.  The Launcher has to live in Guest memory, so it sets
@@ -153,23 +99,17 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
  * pagetables (which are set up by the Launcher).
  *
  * start: The first instruction to execute ("eip" in x86-speak).
- *
- * page_offset: The PAGE_OFFSET constant in the Guest kernel.  We should
- * probably wean the code off this, but it's a very useful constant!  Any
- * address above this is within the Guest kernel, and any kernel address can
- * quickly converted from physical to virtual by adding PAGE_OFFSET.  It's
- * 0xC0000000 (3G) by default, but it's configurable at kernel build time.
  */
-static int initialize(struct file *file, const u32 __user *input)
+static int initialize(struct file *file, const unsigned long __user *input)
 {
         /* "struct lguest" contains everything we (the Host) know about a
          * Guest. */
         struct lguest *lg;
-        int err, i;
-        u32 args[4];
+        int err;
+        unsigned long args[4];
 
-        /* We grab the Big Lguest lock, which protects the global array
-         * "lguests" and multiple simultaneous initializations. */
+        /* We grab the Big Lguest lock, which protects against multiple
+         * simultaneous initializations. */
         mutex_lock(&lguest_lock);
         /* You can't initialize twice!  Close the device and start again... */
         if (file->private_data) {
@@ -182,20 +122,15 @@ static int initialize(struct file *file, const u32 __user *input)
                 goto unlock;
         }
 
-        /* Find an unused guest. */
-        i = find_free_guest();
-        if (i < 0) {
-                err = -ENOSPC;
+        lg = kzalloc(sizeof(*lg), GFP_KERNEL);
+        if (!lg) {
+                err = -ENOMEM;
                 goto unlock;
         }
-        /* OK, we have an index into the "lguest" array: "lg" is a convenient
-         * pointer. */
-        lg = &lguests[i];
 
         /* Populate the easy fields of our "struct lguest" */
-        lg->guestid = i;
-        lg->pfn_limit = args[0];
-        lg->page_offset = args[3];
+        lg->mem_base = (void __user *)(long)args[0];
+        lg->pfn_limit = args[1];
 
         /* We need a complete page for the Guest registers: they are accessible
          * to the Guest and we can only grant it access to whole pages. */
@@ -210,17 +145,13 @@ static int initialize(struct file *file, const u32 __user *input)
         /* Initialize the Guest's shadow page tables, using the toplevel
          * address the Launcher gave us.  This allocates memory, so can
          * fail. */
-        err = init_guest_pagetable(lg, args[1]);
+        err = init_guest_pagetable(lg, args[2]);
         if (err)
                 goto free_regs;
 
         /* Now we initialize the Guest's registers, handing it the start
          * address. */
-        setup_regs(lg->regs, args[2]);
-
-        /* There are a couple of GDT entries the Guest expects when first
-         * booting. */
-        setup_guest_gdt(lg);
+        lguest_arch_setup_regs(lg, args[3]);
 
         /* The timer for lguest's clock needs initialization. */
         init_clockdev(lg);
@@ -260,18 +191,19 @@ unlock:
 /*L:010 The first operation the Launcher does must be a write.  All writes
  * start with a 32 bit number: for the first write this must be
  * LHREQ_INITIALIZE to set up the Guest.  After that the Launcher can use
- * writes of other values to get DMA buffers and send interrupts. */
-static ssize_t write(struct file *file, const char __user *input,
+ * writes of other values to send interrupts. */
+static ssize_t write(struct file *file, const char __user *in,
                      size_t size, loff_t *off)
 {
         /* Once the guest is initialized, we hold the "struct lguest" in the
          * file private data. */
         struct lguest *lg = file->private_data;
-        u32 req;
+        const unsigned long __user *input = (const unsigned long __user *)in;
+        unsigned long req;
 
         if (get_user(req, input) != 0)
                 return -EFAULT;
-        input += sizeof(req);
+        input++;
 
         /* If you haven't initialized, you must do that first. */
         if (req != LHREQ_INITIALIZE && !lg)
@@ -287,13 +219,11 @@ static ssize_t write(struct file *file, const char __user *input,
 
         switch (req) {
         case LHREQ_INITIALIZE:
-                return initialize(file, (const u32 __user *)input);
-        case LHREQ_GETDMA:
-                return user_get_dma(lg, (const u32 __user *)input);
+                return initialize(file, input);
         case LHREQ_IRQ:
-                return user_send_irq(lg, (const u32 __user *)input);
+                return user_send_irq(lg, input);
         case LHREQ_BREAK:
-                return break_guest_out(lg, (const u32 __user *)input);
+                return break_guest_out(lg, input);
         default:
                 return -EINVAL;
         }
@@ -319,8 +249,6 @@ static int close(struct inode *inode, struct file *file)
         mutex_lock(&lguest_lock);
         /* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
         hrtimer_cancel(&lg->hrt);
-        /* Free any DMA buffers the Guest had bound. */
-        release_all_dma(lg);
         /* Free up the shadow page tables for the Guest. */
         free_guest_pagetable(lg);
         /* Now all the memory cleanups are done, it's safe to release the
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index b7a924ace684..2a45f0691c9b 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -13,6 +13,7 @@
 #include <linux/random.h>
 #include <linux/percpu.h>
 #include <asm/tlbflush.h>
+#include <asm/uaccess.h>
 #include "lg.h"
 
 /*M:008 We hold reference to pages, which prevents them from being swapped.
@@ -44,44 +45,32 @@
  *  (vii) Setting up the page tables initially.
  :*/
 
-/* Pages a 4k long, and each page table entry is 4 bytes long, giving us 1024
- * (or 2^10) entries per page. */
-#define PTES_PER_PAGE_SHIFT 10
-#define PTES_PER_PAGE (1 << PTES_PER_PAGE_SHIFT)
 
 /* 1024 entries in a page table page maps 1024 pages: 4MB.  The Switcher is
  * conveniently placed at the top 4MB, so it uses a separate, complete PTE
  * page.  */
-#define SWITCHER_PGD_INDEX (PTES_PER_PAGE - 1)
+#define SWITCHER_PGD_INDEX (PTRS_PER_PGD - 1)
 
 /* We actually need a separate PTE page for each CPU.  Remember that after the
  * Switcher code itself comes two pages for each CPU, and we don't want this
  * CPU's guest to see the pages of any other CPU. */
-static DEFINE_PER_CPU(spte_t *, switcher_pte_pages);
+static DEFINE_PER_CPU(pte_t *, switcher_pte_pages);
 #define switcher_pte_page(cpu) per_cpu(switcher_pte_pages, cpu)
 
 /*H:320 With our shadow and Guest types established, we need to deal with
  * them: the page table code is curly enough to need helper functions to keep
  * it clear and clean.
  *
- * The first helper takes a virtual address, and says which entry in the top
- * level page table deals with that address.  Since each top level entry deals
- * with 4M, this effectively divides by 4M. */
-static unsigned vaddr_to_pgd_index(unsigned long vaddr)
-{
-        return vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
-}
-
-/* There are two functions which return pointers to the shadow (aka "real")
+ * There are two functions which return pointers to the shadow (aka "real")
  * page tables.
  *
  * spgd_addr() takes the virtual address and returns a pointer to the top-level
  * page directory entry for that address.  Since we keep track of several page
  * tables, the "i" argument tells us which one we're interested in (it's
  * usually the current one). */
-static spgd_t *spgd_addr(struct lguest *lg, u32 i, unsigned long vaddr)
+static pgd_t *spgd_addr(struct lguest *lg, u32 i, unsigned long vaddr)
 {
-        unsigned int index = vaddr_to_pgd_index(vaddr);
+        unsigned int index = pgd_index(vaddr);
 
         /* We kill any Guest trying to touch the Switcher addresses. */
         if (index >= SWITCHER_PGD_INDEX) {
@@ -95,28 +84,28 @@ static spgd_t *spgd_addr(struct lguest *lg, u32 i, unsigned long vaddr)
 /* This routine then takes the PGD entry given above, which contains the
  * address of the PTE page.  It then returns a pointer to the PTE entry for the
  * given address. */
-static spte_t *spte_addr(struct lguest *lg, spgd_t spgd, unsigned long vaddr)
+static pte_t *spte_addr(struct lguest *lg, pgd_t spgd, unsigned long vaddr)
 {
-        spte_t *page = __va(spgd.pfn << PAGE_SHIFT);
+        pte_t *page = __va(pgd_pfn(spgd) << PAGE_SHIFT);
         /* You should never call this if the PGD entry wasn't valid */
-        BUG_ON(!(spgd.flags & _PAGE_PRESENT));
-        return &page[(vaddr >> PAGE_SHIFT) % PTES_PER_PAGE];
+        BUG_ON(!(pgd_flags(spgd) & _PAGE_PRESENT));
+        return &page[(vaddr >> PAGE_SHIFT) % PTRS_PER_PTE];
 }
 
 /* These two functions just like the above two, except they access the Guest
  * page tables.  Hence they return a Guest address. */
 static unsigned long gpgd_addr(struct lguest *lg, unsigned long vaddr)
 {
-        unsigned int index = vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
-        return lg->pgdirs[lg->pgdidx].cr3 + index * sizeof(gpgd_t);
+        unsigned int index = vaddr >> (PGDIR_SHIFT);
+        return lg->pgdirs[lg->pgdidx].gpgdir + index * sizeof(pgd_t);
 }
 
 static unsigned long gpte_addr(struct lguest *lg,
-                               gpgd_t gpgd, unsigned long vaddr)
+                               pgd_t gpgd, unsigned long vaddr)
 {
-        unsigned long gpage = gpgd.pfn << PAGE_SHIFT;
-        BUG_ON(!(gpgd.flags & _PAGE_PRESENT));
-        return gpage + ((vaddr>>PAGE_SHIFT) % PTES_PER_PAGE) * sizeof(gpte_t);
+        unsigned long gpage = pgd_pfn(gpgd) << PAGE_SHIFT;
+        BUG_ON(!(pgd_flags(gpgd) & _PAGE_PRESENT));
+        return gpage + ((vaddr>>PAGE_SHIFT) % PTRS_PER_PTE) * sizeof(pte_t);
 }
 
 /*H:350 This routine takes a page number given by the Guest and converts it to
@@ -149,53 +138,55 @@ static unsigned long get_pfn(unsigned long virtpfn, int write)
  * entry can be a little tricky.  The flags are (almost) the same, but the
  * Guest PTE contains a virtual page number: the CPU needs the real page
  * number. */
-static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write)
+static pte_t gpte_to_spte(struct lguest *lg, pte_t gpte, int write)
 {
-        spte_t spte;
-        unsigned long pfn;
+        unsigned long pfn, base, flags;
 
         /* The Guest sets the global flag, because it thinks that it is using
          * PGE.  We only told it to use PGE so it would tell us whether it was
          * flushing a kernel mapping or a userspace mapping.  We don't actually
          * use the global bit, so throw it away. */
-        spte.flags = (gpte.flags & ~_PAGE_GLOBAL);
+        flags = (pte_flags(gpte) & ~_PAGE_GLOBAL);
+
+        /* The Guest's pages are offset inside the Launcher. */
+        base = (unsigned long)lg->mem_base / PAGE_SIZE;
 
         /* We need a temporary "unsigned long" variable to hold the answer from
          * get_pfn(), because it returns 0xFFFFFFFF on failure, which wouldn't
          * fit in spte.pfn.  get_pfn() finds the real physical number of the
          * page, given the virtual number. */
-        pfn = get_pfn(gpte.pfn, write);
+        pfn = get_pfn(base + pte_pfn(gpte), write);
         if (pfn == -1UL) {
-                kill_guest(lg, "failed to get page %u", gpte.pfn);
+                kill_guest(lg, "failed to get page %lu", pte_pfn(gpte));
                 /* When we destroy the Guest, we'll go through the shadow page
                  * tables and release_pte() them.  Make sure we don't think
                  * this one is valid! */
-                spte.flags = 0;
+                flags = 0;
         }
-        /* Now we assign the page number, and our shadow PTE is complete. */
-        spte.pfn = pfn;
-        return spte;
+        /* Now we assemble our shadow PTE from the page number and flags. */
+        return pfn_pte(pfn, __pgprot(flags));
 }
 
 /*H:460 And to complete the chain, release_pte() looks like this: */
-static void release_pte(spte_t pte)
+static void release_pte(pte_t pte)
 {
         /* Remember that get_user_pages() took a reference to the page, in
          * get_pfn()?  We have to put it back now. */
-        if (pte.flags & _PAGE_PRESENT)
-                put_page(pfn_to_page(pte.pfn));
+        if (pte_flags(pte) & _PAGE_PRESENT)
+                put_page(pfn_to_page(pte_pfn(pte)));
 }
 /*:*/
 
-static void check_gpte(struct lguest *lg, gpte_t gpte)
+static void check_gpte(struct lguest *lg, pte_t gpte)
 {
-        if ((gpte.flags & (_PAGE_PWT|_PAGE_PSE)) || gpte.pfn >= lg->pfn_limit)
+        if ((pte_flags(gpte) & (_PAGE_PWT|_PAGE_PSE))
+            || pte_pfn(gpte) >= lg->pfn_limit)
                 kill_guest(lg, "bad page table entry");
 }
 
-static void check_gpgd(struct lguest *lg, gpgd_t gpgd)
+static void check_gpgd(struct lguest *lg, pgd_t gpgd)
 {
-        if ((gpgd.flags & ~_PAGE_TABLE) || gpgd.pfn >= lg->pfn_limit)
+        if ((pgd_flags(gpgd) & ~_PAGE_TABLE) || pgd_pfn(gpgd) >= lg->pfn_limit)
                 kill_guest(lg, "bad page directory entry");
 }
 
@@ -211,21 +202,21 @@ static void check_gpgd(struct lguest *lg, gpgd_t gpgd)
  * true. */
 int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
 {
-        gpgd_t gpgd;
-        spgd_t *spgd;
+        pgd_t gpgd;
+        pgd_t *spgd;
         unsigned long gpte_ptr;
-        gpte_t gpte;
-        spte_t *spte;
+        pte_t gpte;
+        pte_t *spte;
 
         /* First step: get the top-level Guest page table entry. */
-        gpgd = mkgpgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
+        gpgd = lgread(lg, gpgd_addr(lg, vaddr), pgd_t);
         /* Toplevel not present?  We can't map it in. */
-        if (!(gpgd.flags & _PAGE_PRESENT))
+        if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
                 return 0;
 
         /* Now look at the matching shadow entry. */
         spgd = spgd_addr(lg, lg->pgdidx, vaddr);
-        if (!(spgd->flags & _PAGE_PRESENT)) {
+        if (!(pgd_flags(*spgd) & _PAGE_PRESENT)) {
                 /* No shadow entry: allocate a new shadow PTE page. */
                 unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
                 /* This is not really the Guest's fault, but killing it is
@@ -238,34 +229,35 @@ int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
                 check_gpgd(lg, gpgd);
                 /* And we copy the flags to the shadow PGD entry.  The page
                  * number in the shadow PGD is the page we just allocated. */
-                spgd->raw.val = (__pa(ptepage) | gpgd.flags);
+                *spgd = __pgd(__pa(ptepage) | pgd_flags(gpgd));
         }
 
         /* OK, now we look at the lower level in the Guest page table: keep its
          * address, because we might update it later. */
         gpte_ptr = gpte_addr(lg, gpgd, vaddr);
-        gpte = mkgpte(lgread_u32(lg, gpte_ptr));
+        gpte = lgread(lg, gpte_ptr, pte_t);
 
         /* If this page isn't in the Guest page tables, we can't page it in. */
-        if (!(gpte.flags & _PAGE_PRESENT))
+        if (!(pte_flags(gpte) & _PAGE_PRESENT))
                 return 0;
 
         /* Check they're not trying to write to a page the Guest wants
          * read-only (bit 2 of errcode == write). */
-        if ((errcode & 2) && !(gpte.flags & _PAGE_RW))
+        if ((errcode & 2) && !(pte_flags(gpte) & _PAGE_RW))
                 return 0;
 
         /* User access to a kernel page? (bit 3 == user access) */
-        if ((errcode & 4) && !(gpte.flags & _PAGE_USER))
+        if ((errcode & 4) && !(pte_flags(gpte) & _PAGE_USER))
                 return 0;
 
         /* Check that the Guest PTE flags are OK, and the page number is below
          * the pfn_limit (ie. not mapping the Launcher binary). */
         check_gpte(lg, gpte);
         /* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
-        gpte.flags |= _PAGE_ACCESSED;
+        gpte = pte_mkyoung(gpte);
+
         if (errcode & 2)
-                gpte.flags |= _PAGE_DIRTY;
+                gpte = pte_mkdirty(gpte);
 
         /* Get the pointer to the shadow PTE entry we're going to set. */
         spte = spte_addr(lg, *spgd, vaddr);
@@ -275,21 +267,18 @@ int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
 
         /* If this is a write, we insist that the Guest page is writable (the
          * final arg to gpte_to_spte()). */
-        if (gpte.flags & _PAGE_DIRTY)
+        if (pte_dirty(gpte))
                 *spte = gpte_to_spte(lg, gpte, 1);
-        else {
+        else
                 /* If this is a read, don't set the "writable" bit in the page
                  * table entry, even if the Guest says it's writable.  That way
                  * we come back here when a write does actually ocur, so we can
                  * update the Guest's _PAGE_DIRTY flag. */
-                gpte_t ro_gpte = gpte;
-                ro_gpte.flags &= ~_PAGE_RW;
-                *spte = gpte_to_spte(lg, ro_gpte, 0);
-        }
+                *spte = gpte_to_spte(lg, pte_wrprotect(gpte), 0);
 
         /* Finally, we write the Guest PTE entry back: we've set the
          * _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags. */
-        lgwrite_u32(lg, gpte_ptr, gpte.raw.val);
+        lgwrite(lg, gpte_ptr, pte_t, gpte);
 
         /* We succeeded in mapping the page! */
         return 1;
@@ -305,17 +294,18 @@ int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
  * mapped by the shadow page tables, and is it writable? */
 static int page_writable(struct lguest *lg, unsigned long vaddr)
 {
-        spgd_t *spgd;
+        pgd_t *spgd;
         unsigned long flags;
 
         /* Look at the top level entry: is it present? */
         spgd = spgd_addr(lg, lg->pgdidx, vaddr);
-        if (!(spgd->flags & _PAGE_PRESENT))
+        if (!(pgd_flags(*spgd) & _PAGE_PRESENT))
                 return 0;
 
         /* Check the flags on the pte entry itself: it must be present and
          * writable. */
-        flags = spte_addr(lg, *spgd, vaddr)->flags;
+        flags = pte_flags(*(spte_addr(lg, *spgd, vaddr)));
+
         return (flags & (_PAGE_PRESENT|_PAGE_RW)) == (_PAGE_PRESENT|_PAGE_RW);
 }
 
@@ -329,22 +319,22 @@ void pin_page(struct lguest *lg, unsigned long vaddr)
 }
 
 /*H:450 If we chase down the release_pgd() code, it looks like this: */
-static void release_pgd(struct lguest *lg, spgd_t *spgd)
+static void release_pgd(struct lguest *lg, pgd_t *spgd)
 {
         /* If the entry's not present, there's nothing to release. */
-        if (spgd->flags & _PAGE_PRESENT) {
+        if (pgd_flags(*spgd) & _PAGE_PRESENT) {
                 unsigned int i;
                 /* Converting the pfn to find the actual PTE page is easy: turn
                  * the page number into a physical address, then convert to a
                  * virtual address (easy for kernel pages like this one). */
-                spte_t *ptepage = __va(spgd->pfn << PAGE_SHIFT);
+                pte_t *ptepage = __va(pgd_pfn(*spgd) << PAGE_SHIFT);
                 /* For each entry in the page, we might need to release it. */
-                for (i = 0; i < PTES_PER_PAGE; i++)
+                for (i = 0; i < PTRS_PER_PTE; i++)
                         release_pte(ptepage[i]);
                 /* Now we can free the page of PTEs */
                 free_page((long)ptepage);
                 /* And zero out the PGD entry we we never release it twice. */
-                spgd->raw.val = 0;
+                *spgd = __pgd(0);
         }
 }
 
@@ -356,7 +346,7 @@ static void flush_user_mappings(struct lguest *lg, int idx)
 {
         unsigned int i;
         /* Release every pgd entry up to the kernel's address. */
-        for (i = 0; i < vaddr_to_pgd_index(lg->page_offset); i++)
+        for (i = 0; i < pgd_index(lg->kernel_address); i++)
                 release_pgd(lg, lg->pgdirs[idx].pgdir + i);
 }
 
@@ -369,6 +359,25 @@ void guest_pagetable_flush_user(struct lguest *lg)
 }
 /*:*/
 
+/* We walk down the guest page tables to get a guest-physical address */
+unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
+{
+        pgd_t gpgd;
+        pte_t gpte;
+
+        /* First step: get the top-level Guest page table entry. */
+        gpgd = lgread(lg, gpgd_addr(lg, vaddr), pgd_t);
+        /* Toplevel not present?  We can't map it in. */
+        if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
+                kill_guest(lg, "Bad address %#lx", vaddr);
+
+        gpte = lgread(lg, gpte_addr(lg, gpgd, vaddr), pte_t);
+        if (!(pte_flags(gpte) & _PAGE_PRESENT))
+                kill_guest(lg, "Bad address %#lx", vaddr);
+
+        return pte_pfn(gpte) * PAGE_SIZE | (vaddr & ~PAGE_MASK);
+}
+
 /* We keep several page tables.  This is a simple routine to find the page
  * table (if any) corresponding to this top-level address the Guest has given
  * us. */
@@ -376,7 +385,7 @@ static unsigned int find_pgdir(struct lguest *lg, unsigned long pgtable)
 {
         unsigned int i;
         for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
-                if (lg->pgdirs[i].cr3 == pgtable)
+                if (lg->pgdirs[i].gpgdir == pgtable)
                         break;
         return i;
 }
@@ -385,7 +394,7 @@ static unsigned int find_pgdir(struct lguest *lg, unsigned long pgtable)
  * allocate a new one (and so the kernel parts are not there), we set
  * blank_pgdir. */
 static unsigned int new_pgdir(struct lguest *lg,
-                              unsigned long cr3,
+                              unsigned long gpgdir,
                               int *blank_pgdir)
 {
         unsigned int next;
@@ -395,7 +404,7 @@ static unsigned int new_pgdir(struct lguest *lg,
         next = random32() % ARRAY_SIZE(lg->pgdirs);
         /* If it's never been allocated at all before, try now. */
         if (!lg->pgdirs[next].pgdir) {
-                lg->pgdirs[next].pgdir = (spgd_t *)get_zeroed_page(GFP_KERNEL);
+                lg->pgdirs[next].pgdir = (pgd_t *)get_zeroed_page(GFP_KERNEL);
                 /* If the allocation fails, just keep using the one we have */
                 if (!lg->pgdirs[next].pgdir)
                         next = lg->pgdidx;
@@ -405,7 +414,7 @@ static unsigned int new_pgdir(struct lguest *lg,
                         *blank_pgdir = 1;
         }
         /* Record which Guest toplevel this shadows. */
-        lg->pgdirs[next].cr3 = cr3;
+        lg->pgdirs[next].gpgdir = gpgdir;
         /* Release all the non-kernel mappings. */
         flush_user_mappings(lg, next);
 
@@ -472,26 +481,27 @@ void guest_pagetable_clear_all(struct lguest *lg)
  * they set _PAGE_DIRTY then we can put a writable PTE entry in immediately.
  */
 static void do_set_pte(struct lguest *lg, int idx,
-                       unsigned long vaddr, gpte_t gpte)
+                       unsigned long vaddr, pte_t gpte)
 {
         /* Look up the matching shadow page directot entry. */
-        spgd_t *spgd = spgd_addr(lg, idx, vaddr);
+        pgd_t *spgd = spgd_addr(lg, idx, vaddr);
 
         /* If the top level isn't present, there's no entry to update. */
-        if (spgd->flags & _PAGE_PRESENT) {
+        if (pgd_flags(*spgd) & _PAGE_PRESENT) {
                 /* Otherwise, we start by releasing the existing entry. */
-                spte_t *spte = spte_addr(lg, *spgd, vaddr);
+                pte_t *spte = spte_addr(lg, *spgd, vaddr);
                 release_pte(*spte);
 
                 /* If they're setting this entry as dirty or accessed, we might
                  * as well put that entry they've given us in now.  This shaves
                  * 10% off a copy-on-write micro-benchmark. */
-                if (gpte.flags & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
+                if (pte_flags(gpte) & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
                         check_gpte(lg, gpte);
-                        *spte = gpte_to_spte(lg, gpte, gpte.flags&_PAGE_DIRTY);
+                        *spte = gpte_to_spte(lg, gpte,
+                                             pte_flags(gpte) & _PAGE_DIRTY);
                 } else
                         /* Otherwise we can demand_page() it in later. */
-                        spte->raw.val = 0;
+                        *spte = __pte(0);
         }
 }
 
@@ -506,18 +516,18 @@ static void do_set_pte(struct lguest *lg, int idx,
  * The benefit is that when we have to track a new page table, we can copy keep
  * all the kernel mappings.  This speeds up context switch immensely. */
 void guest_set_pte(struct lguest *lg,
-                   unsigned long cr3, unsigned long vaddr, gpte_t gpte)
+                   unsigned long gpgdir, unsigned long vaddr, pte_t gpte)
 {
         /* Kernel mappings must be changed on all top levels.  Slow, but
          * doesn't happen often. */
-        if (vaddr >= lg->page_offset) {
+        if (vaddr >= lg->kernel_address) {
                 unsigned int i;
                 for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
                         if (lg->pgdirs[i].pgdir)
                                 do_set_pte(lg, i, vaddr, gpte);
         } else {
                 /* Is this page table one we have a shadow for? */
-                int pgdir = find_pgdir(lg, cr3);
+                int pgdir = find_pgdir(lg, gpgdir);
                 if (pgdir != ARRAY_SIZE(lg->pgdirs))
                         /* If so, do the update. */
                         do_set_pte(lg, pgdir, vaddr, gpte);
@@ -538,7 +548,7 @@ void guest_set_pte(struct lguest *lg,
  *
  * So with that in mind here's our code to to update a (top-level) PGD entry:
  */
-void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 idx)
+void guest_set_pmd(struct lguest *lg, unsigned long gpgdir, u32 idx)
 {
         int pgdir;
 
@@ -548,7 +558,7 @@ void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 idx)
                 return;
 
         /* If they're talking about a page table we have a shadow for... */
-        pgdir = find_pgdir(lg, cr3);
+        pgdir = find_pgdir(lg, gpgdir);
         if (pgdir < ARRAY_SIZE(lg->pgdirs))
                 /* ... throw it away. */
                 release_pgd(lg, lg->pgdirs[pgdir].pgdir + idx);
@@ -560,21 +570,34 @@ void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 idx)
  * its first page table is.  We set some things up here: */
 int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
 {
-        /* In flush_user_mappings() we loop from 0 to
-         * "vaddr_to_pgd_index(lg->page_offset)".  This assumes it won't hit
-         * the Switcher mappings, so check that now. */
-        if (vaddr_to_pgd_index(lg->page_offset) >= SWITCHER_PGD_INDEX)
-                return -EINVAL;
         /* We start on the first shadow page table, and give it a blank PGD
          * page. */
         lg->pgdidx = 0;
-        lg->pgdirs[lg->pgdidx].cr3 = pgtable;
-        lg->pgdirs[lg->pgdidx].pgdir = (spgd_t*)get_zeroed_page(GFP_KERNEL);
+        lg->pgdirs[lg->pgdidx].gpgdir = pgtable;
+        lg->pgdirs[lg->pgdidx].pgdir = (pgd_t*)get_zeroed_page(GFP_KERNEL);
         if (!lg->pgdirs[lg->pgdidx].pgdir)
                 return -ENOMEM;
         return 0;
 }
 
+/* When the Guest calls LHCALL_LGUEST_INIT we do more setup. */
+void page_table_guest_data_init(struct lguest *lg)
+{
+        /* We get the kernel address: above this is all kernel memory. */
+        if (get_user(lg->kernel_address, &lg->lguest_data->kernel_address)
+            /* We tell the Guest that it can't use the top 4MB of virtual
+             * addresses used by the Switcher. */
+            || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
+            || put_user(lg->pgdirs[lg->pgdidx].gpgdir,&lg->lguest_data->pgdir))
+                kill_guest(lg, "bad guest page %p", lg->lguest_data);
+
+        /* In flush_user_mappings() we loop from 0 to
+         * "pgd_index(lg->kernel_address)".  This assumes it won't hit the
+         * Switcher mappings, so check that now. */
+        if (pgd_index(lg->kernel_address) >= SWITCHER_PGD_INDEX)
+                kill_guest(lg, "bad kernel address %#lx", lg->kernel_address);
+}
+
 /* When a Guest dies, our cleanup is fairly simple. */
 void free_guest_pagetable(struct lguest *lg)
 {
@@ -594,14 +617,14 @@ void free_guest_pagetable(struct lguest *lg)
  * for each CPU already set up, we just need to hook them in. */
 void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages)
 {
-        spte_t *switcher_pte_page = __get_cpu_var(switcher_pte_pages);
-        spgd_t switcher_pgd;
-        spte_t regs_pte;
+        pte_t *switcher_pte_page = __get_cpu_var(switcher_pte_pages);
+        pgd_t switcher_pgd;
+        pte_t regs_pte;
 
         /* Make the last PGD entry for this Guest point to the Switcher's PTE
          * page for this CPU (with appropriate flags). */
-        switcher_pgd.pfn = __pa(switcher_pte_page) >> PAGE_SHIFT;
-        switcher_pgd.flags = _PAGE_KERNEL;
+        switcher_pgd = __pgd(__pa(switcher_pte_page) | _PAGE_KERNEL);
+
         lg->pgdirs[lg->pgdidx].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;
 
         /* We also change the Switcher PTE page.  When we're running the Guest,
@@ -611,10 +634,8 @@ void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages)
          * CPU's "struct lguest_pages": if we make sure the Guest's register
          * page is already mapped there, we don't have to copy them out
          * again. */
-        regs_pte.pfn = __pa(lg->regs_page) >> PAGE_SHIFT;
-        regs_pte.flags = _PAGE_KERNEL;
-        switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTES_PER_PAGE]
-                = regs_pte;
+        regs_pte = pfn_pte (__pa(lg->regs_page) >> PAGE_SHIFT, __pgprot(_PAGE_KERNEL));
+        switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTRS_PER_PTE] = regs_pte;
 }
 /*:*/
 
@@ -635,24 +656,25 @@ static __init void populate_switcher_pte_page(unsigned int cpu,
                                               unsigned int pages)
 {
         unsigned int i;
-        spte_t *pte = switcher_pte_page(cpu);
+        pte_t *pte = switcher_pte_page(cpu);
 
         /* The first entries are easy: they map the Switcher code. */
         for (i = 0; i < pages; i++) {
-                pte[i].pfn = page_to_pfn(switcher_page[i]);
-                pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
+                pte[i] = mk_pte(switcher_page[i],
+                                __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED));
         }
 
         /* The only other thing we map is this CPU's pair of pages. */
         i = pages + cpu*2;
 
         /* First page (Guest registers) is writable from the Guest */
-        pte[i].pfn = page_to_pfn(switcher_page[i]);
-        pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW;
+        pte[i] = pfn_pte(page_to_pfn(switcher_page[i]),
+                         __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW));
+
         /* The second page contains the "struct lguest_ro_state", and is
          * read-only. */
-        pte[i+1].pfn = page_to_pfn(switcher_page[i+1]);
-        pte[i+1].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
+        pte[i+1] = pfn_pte(page_to_pfn(switcher_page[i+1]),
+                           __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED));
 }
 
 /*H:510 At boot or module load time, init_pagetables() allocates and populates
@@ -662,7 +684,7 @@ __init int init_pagetables(struct page **switcher_page, unsigned int pages)
         unsigned int i;
 
         for_each_possible_cpu(i) {
-                switcher_pte_page(i) = (spte_t *)get_zeroed_page(GFP_KERNEL);
+                switcher_pte_page(i) = (pte_t *)get_zeroed_page(GFP_KERNEL);
                 if (!switcher_pte_page(i)) {
                         free_switcher_pte_pages();
                         return -ENOMEM;
diff --git a/drivers/lguest/segments.c b/drivers/lguest/segments.c
index 9b81119f46e9..c2434ec99f7b 100644
--- a/drivers/lguest/segments.c
+++ b/drivers/lguest/segments.c
@@ -73,14 +73,14 @@ static void fixup_gdt_table(struct lguest *lg, unsigned start, unsigned end)
                 /* Segment descriptors contain a privilege level: the Guest is
                  * sometimes careless and leaves this as 0, even though it's
                  * running at privilege level 1.  If so, we fix it here. */
-                if ((lg->gdt[i].b & 0x00006000) == 0)
-                        lg->gdt[i].b |= (GUEST_PL << 13);
+                if ((lg->arch.gdt[i].b & 0x00006000) == 0)
+                        lg->arch.gdt[i].b |= (GUEST_PL << 13);
 
                 /* Each descriptor has an "accessed" bit.  If we don't set it
                  * now, the CPU will try to set it when the Guest first loads
                  * that entry into a segment register.  But the GDT isn't
                  * writable by the Guest, so bad things can happen. */
-                lg->gdt[i].b |= 0x00000100;
+                lg->arch.gdt[i].b |= 0x00000100;
         }
 }
 
@@ -106,12 +106,12 @@ void setup_default_gdt_entries(struct lguest_ro_state *state)
 void setup_guest_gdt(struct lguest *lg)
 {
         /* Start with full 0-4G segments... */
-        lg->gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
-        lg->gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
+        lg->arch.gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
+        lg->arch.gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
         /* ...except the Guest is allowed to use them, so set the privilege
          * level appropriately in the flags. */
-        lg->gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
-        lg->gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
+        lg->arch.gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
+        lg->arch.gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
 }
 
 /* Like the IDT, we never simply use the GDT the Guest gives us.  We set up the
@@ -126,7 +126,7 @@ void copy_gdt_tls(const struct lguest *lg, struct desc_struct *gdt)
         unsigned int i;
 
         for (i = GDT_ENTRY_TLS_MIN; i <= GDT_ENTRY_TLS_MAX; i++)
-                gdt[i] = lg->gdt[i];
+                gdt[i] = lg->arch.gdt[i];
 }
 
 /* This is the full version */
@@ -138,7 +138,7 @@ void copy_gdt(const struct lguest *lg, struct desc_struct *gdt)
          * replaced.  See ignored_gdt() above. */
         for (i = 0; i < GDT_ENTRIES; i++)
                 if (!ignored_gdt(i))
-                        gdt[i] = lg->gdt[i];
+                        gdt[i] = lg->arch.gdt[i];
 }
 
 /* This is where the Guest asks us to load a new GDT (LHCALL_LOAD_GDT). */
@@ -146,12 +146,12 @@ void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num)
 {
         /* We assume the Guest has the same number of GDT entries as the
          * Host, otherwise we'd have to dynamically allocate the Guest GDT. */
-        if (num > ARRAY_SIZE(lg->gdt))
+        if (num > ARRAY_SIZE(lg->arch.gdt))
                 kill_guest(lg, "too many gdt entries %i", num);
 
         /* We read the whole thing in, then fix it up. */
-        lgread(lg, lg->gdt, table, num * sizeof(lg->gdt[0]));
-        fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->gdt));
+        __lgread(lg, lg->arch.gdt, table, num * sizeof(lg->arch.gdt[0]));
+        fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->arch.gdt));
         /* Mark that the GDT changed so the core knows it has to copy it again,
          * even if the Guest is run on the same CPU. */
         lg->changed |= CHANGED_GDT;
@@ -159,9 +159,9 @@ void load_guest_gdt(struct lguest *lg, unsigned long table, u32 num)
 
 void guest_load_tls(struct lguest *lg, unsigned long gtls)
 {
-        struct desc_struct *tls = &lg->gdt[GDT_ENTRY_TLS_MIN];
+        struct desc_struct *tls = &lg->arch.gdt[GDT_ENTRY_TLS_MIN];
 
-        lgread(lg, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
+        __lgread(lg, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
         fixup_gdt_table(lg, GDT_ENTRY_TLS_MIN, GDT_ENTRY_TLS_MAX+1);
         lg->changed |= CHANGED_GDT_TLS;
 }
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
new file mode 100644
index 000000000000..9eed12d5a395
--- /dev/null
+++ b/drivers/lguest/x86/core.c
@@ -0,0 +1,577 @@
+/*
+ * Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation.
+ * Copyright (C) 2007, Jes Sorensen <jes@sgi.com> SGI.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/kernel.h>
+#include <linux/start_kernel.h>
+#include <linux/string.h>
+#include <linux/console.h>
+#include <linux/screen_info.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/lguest.h>
+#include <linux/lguest_launcher.h>
+#include <asm/paravirt.h>
+#include <asm/param.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/desc.h>
+#include <asm/setup.h>
+#include <asm/lguest.h>
+#include <asm/uaccess.h>
+#include <asm/i387.h>
+#include "../lg.h"
+
+static int cpu_had_pge;
+
+static struct {
+        unsigned long offset;
+        unsigned short segment;
+} lguest_entry;
+
+/* Offset from where switcher.S was compiled to where we've copied it */
+static unsigned long switcher_offset(void)
+{
+        return SWITCHER_ADDR - (unsigned long)start_switcher_text;
+}
+
+/* This cpu's struct lguest_pages. */
+static struct lguest_pages *lguest_pages(unsigned int cpu)
+{
+        return &(((struct lguest_pages *)
+                  (SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
+}
+
+static DEFINE_PER_CPU(struct lguest *, last_guest);
+
+/*S:010
+ * We are getting close to the Switcher.
+ *
+ * Remember that each CPU has two pages which are visible to the Guest when it
+ * runs on that CPU.  This has to contain the state for that Guest: we copy the
+ * state in just before we run the Guest.
+ *
+ * Each Guest has "changed" flags which indicate what has changed in the Guest
+ * since it last ran.  We saw this set in interrupts_and_traps.c and
+ * segments.c.
+ */
+static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
+{
+        /* Copying all this data can be quite expensive.  We usually run the
+         * same Guest we ran last time (and that Guest hasn't run anywhere else
+         * meanwhile).  If that's not the case, we pretend everything in the
+         * Guest has changed. */
+        if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
+                __get_cpu_var(last_guest) = lg;
+                lg->last_pages = pages;
+                lg->changed = CHANGED_ALL;
+        }
+
+        /* These copies are pretty cheap, so we do them unconditionally: */
+        /* Save the current Host top-level page directory. */
+        pages->state.host_cr3 = __pa(current->mm->pgd);
+        /* Set up the Guest's page tables to see this CPU's pages (and no
+         * other CPU's pages). */
+        map_switcher_in_guest(lg, pages);
+        /* Set up the two "TSS" members which tell the CPU what stack to use
+         * for traps which do directly into the Guest (ie. traps at privilege
+         * level 1). */
+        pages->state.guest_tss.esp1 = lg->esp1;
+        pages->state.guest_tss.ss1 = lg->ss1;
+
+        /* Copy direct-to-Guest trap entries. */
+        if (lg->changed & CHANGED_IDT)
+                copy_traps(lg, pages->state.guest_idt, default_idt_entries);
+
+        /* Copy all GDT entries which the Guest can change. */
+        if (lg->changed & CHANGED_GDT)
+                copy_gdt(lg, pages->state.guest_gdt);
+        /* If only the TLS entries have changed, copy them. */
+        else if (lg->changed & CHANGED_GDT_TLS)
+                copy_gdt_tls(lg, pages->state.guest_gdt);
+
+        /* Mark the Guest as unchanged for next time. */
+        lg->changed = 0;
+}
+
+/* Finally: the code to actually call into the Switcher to run the Guest. */
+static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
+{
+        /* This is a dummy value we need for GCC's sake. */
+        unsigned int clobber;
+
+        /* Copy the guest-specific information into this CPU's "struct
+         * lguest_pages". */
+        copy_in_guest_info(lg, pages);
+
+        /* Set the trap number to 256 (impossible value).  If we fault while
+         * switching to the Guest (bad segment registers or bug), this will
+         * cause us to abort the Guest. */
+        lg->regs->trapnum = 256;
+
+        /* Now: we push the "eflags" register on the stack, then do an "lcall".
+         * This is how we change from using the kernel code segment to using
+         * the dedicated lguest code segment, as well as jumping into the
+         * Switcher.
+         *
+         * The lcall also pushes the old code segment (KERNEL_CS) onto the
+         * stack, then the address of this call.  This stack layout happens to
+         * exactly match the stack of an interrupt... */
+        asm volatile("pushf; lcall *lguest_entry"
+                     /* This is how we tell GCC that %eax ("a") and %ebx ("b")
+                      * are changed by this routine.  The "=" means output. */
+                     : "=a"(clobber), "=b"(clobber)
+                     /* %eax contains the pages pointer.  ("0" refers to the
+                      * 0-th argument above, ie "a").  %ebx contains the
+                      * physical address of the Guest's top-level page
+                      * directory. */
+                     : "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
+                     /* We tell gcc that all these registers could change,
+                      * which means we don't have to save and restore them in
+                      * the Switcher. */
+                     : "memory", "%edx", "%ecx", "%edi", "%esi");
+}
+/*:*/
+
+/*H:040 This is the i386-specific code to setup and run the Guest.  Interrupts
+ * are disabled: we own the CPU. */
+void lguest_arch_run_guest(struct lguest *lg)
+{
+        /* Remember the awfully-named TS bit?  If the Guest has asked
+         * to set it we set it now, so we can trap and pass that trap
+         * to the Guest if it uses the FPU. */
+        if (lg->ts)
+                lguest_set_ts();
+
+        /* SYSENTER is an optimized way of doing system calls.  We
+         * can't allow it because it always jumps to privilege level 0.
+         * A normal Guest won't try it because we don't advertise it in
+         * CPUID, but a malicious Guest (or malicious Guest userspace
+         * program) could, so we tell the CPU to disable it before
+         * running the Guest. */
+        if (boot_cpu_has(X86_FEATURE_SEP))
+                wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
+
+        /* Now we actually run the Guest.  It will pop back out when
+         * something interesting happens, and we can examine its
+         * registers to see what it was doing. */
+        run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
+
+        /* The "regs" pointer contains two extra entries which are not
+         * really registers: a trap number which says what interrupt or
+         * trap made the switcher code come back, and an error code
+         * which some traps set.  */
+
+        /* If the Guest page faulted, then the cr2 register will tell
+         * us the bad virtual address.  We have to grab this now,
+         * because once we re-enable interrupts an interrupt could
+         * fault and thus overwrite cr2, or we could even move off to a
+         * different CPU. */
+        if (lg->regs->trapnum == 14)
+                lg->arch.last_pagefault = read_cr2();
+        /* Similarly, if we took a trap because the Guest used the FPU,
+         * we have to restore the FPU it expects to see. */
+        else if (lg->regs->trapnum == 7)
+                math_state_restore();
+
+        /* Restore SYSENTER if it's supposed to be on. */
+        if (boot_cpu_has(X86_FEATURE_SEP))
+                wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
+}
+
+/*H:130 Our Guest is usually so well behaved; it never tries to do things it
+ * isn't allowed to.  Unfortunately, Linux's paravirtual infrastructure isn't
+ * quite complete, because it doesn't contain replacements for the Intel I/O
+ * instructions.  As a result, the Guest sometimes fumbles across one during
+ * the boot process as it probes for various things which are usually attached
+ * to a PC.
+ *
+ * When the Guest uses one of these instructions, we get trap #13 (General
+ * Protection Fault) and come here.  We see if it's one of those troublesome
+ * instructions and skip over it.  We return true if we did. */
+static int emulate_insn(struct lguest *lg)
+{
+        u8 insn;
+        unsigned int insnlen = 0, in = 0, shift = 0;
+        /* The eip contains the *virtual* address of the Guest's instruction:
+         * guest_pa just subtracts the Guest's page_offset. */
+        unsigned long physaddr = guest_pa(lg, lg->regs->eip);
+
+        /* This must be the Guest kernel trying to do something, not userspace!
+         * The bottom two bits of the CS segment register are the privilege
+         * level. */
+        if ((lg->regs->cs & 3) != GUEST_PL)
+                return 0;
+
+        /* Decoding x86 instructions is icky. */
+        insn = lgread(lg, physaddr, u8);
+
+        /* 0x66 is an "operand prefix".  It means it's using the upper 16 bits
+           of the eax register. */
+        if (insn == 0x66) {
+                shift = 16;
+                /* The instruction is 1 byte so far, read the next byte. */
+                insnlen = 1;
+                insn = lgread(lg, physaddr + insnlen, u8);
+        }
+
+        /* We can ignore the lower bit for the moment and decode the 4 opcodes
+         * we need to emulate. */
+        switch (insn & 0xFE) {
+        case 0xE4: /* in     <next byte>,%al */
+                insnlen += 2;
+                in = 1;
+                break;
+        case 0xEC: /* in     (%dx),%al */
+                insnlen += 1;
+                in = 1;
+                break;
+        case 0xE6: /* out    %al,<next byte> */
+                insnlen += 2;
+                break;
+        case 0xEE: /* out    %al,(%dx) */
+                insnlen += 1;
+                break;
+        default:
+                /* OK, we don't know what this is, can't emulate. */
+                return 0;
+        }
+
+        /* If it was an "IN" instruction, they expect the result to be read
+         * into %eax, so we change %eax.  We always return all-ones, which
+         * traditionally means "there's nothing there". */
+        if (in) {
+                /* Lower bit tells is whether it's a 16 or 32 bit access */
+                if (insn & 0x1)
+                        lg->regs->eax = 0xFFFFFFFF;
+                else
+                        lg->regs->eax |= (0xFFFF << shift);
+        }
+        /* Finally, we've "done" the instruction, so move past it. */
+        lg->regs->eip += insnlen;
+        /* Success! */
+        return 1;
+}
+
+/*H:050 Once we've re-enabled interrupts, we look at why the Guest exited. */
+void lguest_arch_handle_trap(struct lguest *lg)
+{
+        switch (lg->regs->trapnum) {
+        case 13: /* We've intercepted a GPF. */
+                 /* Check if this was one of those annoying IN or OUT
+                  * instructions which we need to emulate.  If so, we
+                  * just go back into the Guest after we've done it. */
+                if (lg->regs->errcode == 0) {
+                        if (emulate_insn(lg))
+                                return;
+                }
+                break;
+        case 14: /* We've intercepted a page fault. */
+                 /* The Guest accessed a virtual address that wasn't
+                  * mapped.  This happens a lot: we don't actually set
+                  * up most of the page tables for the Guest at all when
+                  * we start: as it runs it asks for more and more, and
+                  * we set them up as required. In this case, we don't
+                  * even tell the Guest that the fault happened.
+                  *
+                  * The errcode tells whether this was a read or a
+                  * write, and whether kernel or userspace code. */
+                if (demand_page(lg, lg->arch.last_pagefault, lg->regs->errcode))
+                        return;
+
+                 /* OK, it's really not there (or not OK): the Guest
+                  * needs to know.  We write out the cr2 value so it
+                  * knows where the fault occurred.
+                  *
+                  * Note that if the Guest were really messed up, this
+                  * could happen before it's done the INITIALIZE
+                  * hypercall, so lg->lguest_data will be NULL */
+                if (lg->lguest_data &&
+                    put_user(lg->arch.last_pagefault, &lg->lguest_data->cr2))
+                        kill_guest(lg, "Writing cr2");
+                break;
+        case 7: /* We've intercepted a Device Not Available fault. */
+                /* If the Guest doesn't want to know, we already
+                 * restored the Floating Point Unit, so we just
+                 * continue without telling it. */
+                if (!lg->ts)
+                        return;
+                break;
+        case 32 ... 255:
+                /* These values mean a real interrupt occurred, in which case
+                 * the Host handler has already been run.  We just do a
+                 * friendly check if another process should now be run, then
+                 * return to run the Guest again */
+                cond_resched();
+                return;
+        case LGUEST_TRAP_ENTRY:
+                /* Our 'struct hcall_args' maps directly over our regs: we set
+                 * up the pointer now to indicate a hypercall is pending. */
+                lg->hcall = (struct hcall_args *)lg->regs;
+                return;
+        }
+
+        /* We didn't handle the trap, so it needs to go to the Guest. */
+        if (!deliver_trap(lg, lg->regs->trapnum))
+                /* If the Guest doesn't have a handler (either it hasn't
+                 * registered any yet, or it's one of the faults we don't let
+                 * it handle), it dies with a cryptic error message. */
+                kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
+                           lg->regs->trapnum, lg->regs->eip,
+                           lg->regs->trapnum == 14 ? lg->arch.last_pagefault
+                           : lg->regs->errcode);
+}
+
+/* Now we can look at each of the routines this calls, in increasing order of
+ * complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
+ * deliver_trap() and demand_page().  After all those, we'll be ready to
+ * examine the Switcher, and our philosophical understanding of the Host/Guest
+ * duality will be complete. :*/
+static void adjust_pge(void *on)
+{
+        if (on)
+                write_cr4(read_cr4() | X86_CR4_PGE);
+        else
+                write_cr4(read_cr4() & ~X86_CR4_PGE);
+}
+
+/*H:020 Now the Switcher is mapped and every thing else is ready, we need to do
+ * some more i386-specific initialization. */
+void __init lguest_arch_host_init(void)
+{
+        int i;
+
+        /* Most of the i386/switcher.S doesn't care that it's been moved; on
+         * Intel, jumps are relative, and it doesn't access any references to
+         * external code or data.
+         *
+         * The only exception is the interrupt handlers in switcher.S: their
+         * addresses are placed in a table (default_idt_entries), so we need to
+         * update the table with the new addresses.  switcher_offset() is a
+         * convenience function which returns the distance between the builtin
+         * switcher code and the high-mapped copy we just made. */
+        for (i = 0; i < IDT_ENTRIES; i++)
+                default_idt_entries[i] += switcher_offset();
+
+        /*
+         * Set up the Switcher's per-cpu areas.
+         *
+         * Each CPU gets two pages of its own within the high-mapped region
+         * (aka. "struct lguest_pages").  Much of this can be initialized now,
+         * but some depends on what Guest we are running (which is set up in
+         * copy_in_guest_info()).
+         */
+        for_each_possible_cpu(i) {
+                /* lguest_pages() returns this CPU's two pages. */
+                struct lguest_pages *pages = lguest_pages(i);
+                /* This is a convenience pointer to make the code fit one
+                 * statement to a line. */
+                struct lguest_ro_state *state = &pages->state;
+
+                /* The Global Descriptor Table: the Host has a different one
+                 * for each CPU.  We keep a descriptor for the GDT which says
+                 * where it is and how big it is (the size is actually the last
+                 * byte, not the size, hence the "-1"). */
+                state->host_gdt_desc.size = GDT_SIZE-1;
+                state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
+
+                /* All CPUs on the Host use the same Interrupt Descriptor
+                 * Table, so we just use store_idt(), which gets this CPU's IDT
+                 * descriptor. */
+                store_idt(&state->host_idt_desc);
+
+                /* The descriptors for the Guest's GDT and IDT can be filled
+                 * out now, too.  We copy the GDT & IDT into ->guest_gdt and
+                 * ->guest_idt before actually running the Guest. */
+                state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
+                state->guest_idt_desc.address = (long)&state->guest_idt;
+                state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
+                state->guest_gdt_desc.address = (long)&state->guest_gdt;
+
+                /* We know where we want the stack to be when the Guest enters
+                 * the switcher: in pages->regs.  The stack grows upwards, so
+                 * we start it at the end of that structure. */
+                state->guest_tss.esp0 = (long)(&pages->regs + 1);
+                /* And this is the GDT entry to use for the stack: we keep a
+                 * couple of special LGUEST entries. */
+                state->guest_tss.ss0 = LGUEST_DS;
+
+                /* x86 can have a finegrained bitmap which indicates what I/O
+                 * ports the process can use.  We set it to the end of our
+                 * structure, meaning "none". */
+                state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
+
+                /* Some GDT entries are the same across all Guests, so we can
+                 * set them up now. */
+                setup_default_gdt_entries(state);
+                /* Most IDT entries are the same for all Guests, too.*/
+                setup_default_idt_entries(state, default_idt_entries);
+
+                /* The Host needs to be able to use the LGUEST segments on this
+                 * CPU, too, so put them in the Host GDT. */
+                get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
+                get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
+        }
+
+        /* In the Switcher, we want the %cs segment register to use the
+         * LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
+         * it will be undisturbed when we switch.  To change %cs and jump we
+         * need this structure to feed to Intel's "lcall" instruction. */
+        lguest_entry.offset = (long)switch_to_guest + switcher_offset();
+        lguest_entry.segment = LGUEST_CS;
+
+        /* Finally, we need to turn off "Page Global Enable".  PGE is an
+         * optimization where page table entries are specially marked to show
+         * they never change.  The Host kernel marks all the kernel pages this
+         * way because it's always present, even when userspace is running.
+         *
+         * Lguest breaks this: unbeknownst to the rest of the Host kernel, we
+         * switch to the Guest kernel.  If you don't disable this on all CPUs,
+         * you'll get really weird bugs that you'll chase for two days.
+         *
+         * I used to turn PGE off every time we switched to the Guest and back
+         * on when we return, but that slowed the Switcher down noticibly. */
+
+        /* We don't need the complexity of CPUs coming and going while we're
+         * doing this. */
+        lock_cpu_hotplug();
+        if (cpu_has_pge) { /* We have a broader idea of "global". */
+                /* Remember that this was originally set (for cleanup). */
+                cpu_had_pge = 1;
+                /* adjust_pge is a helper function which sets or unsets the PGE
+                 * bit on its CPU, depending on the argument (0 == unset). */
+                on_each_cpu(adjust_pge, (void *)0, 0, 1);
+                /* Turn off the feature in the global feature set. */
+                clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
+        }
+        unlock_cpu_hotplug();
+};
+/*:*/
+
+void __exit lguest_arch_host_fini(void)
+{
+        /* If we had PGE before we started, turn it back on now. */
+        lock_cpu_hotplug();
+        if (cpu_had_pge) {
+                set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
+                /* adjust_pge's argument "1" means set PGE. */
+                on_each_cpu(adjust_pge, (void *)1, 0, 1);
+        }
+        unlock_cpu_hotplug();
+}
+
+
+/*H:122 The i386-specific hypercalls simply farm out to the right functions. */
+int lguest_arch_do_hcall(struct lguest *lg, struct hcall_args *args)
+{
+        switch (args->arg0) {
+        case LHCALL_LOAD_GDT:
+                load_guest_gdt(lg, args->arg1, args->arg2);
+                break;
+        case LHCALL_LOAD_IDT_ENTRY:
+                load_guest_idt_entry(lg, args->arg1, args->arg2, args->arg3);
+                break;
+        case LHCALL_LOAD_TLS:
+                guest_load_tls(lg, args->arg1);
+                break;
+        default:
+                /* Bad Guest.  Bad! */
+                return -EIO;
+        }
+        return 0;
+}
+
+/*H:126 i386-specific hypercall initialization: */
+int lguest_arch_init_hypercalls(struct lguest *lg)
+{
+        u32 tsc_speed;
+
+        /* The pointer to the Guest's "struct lguest_data" is the only
+         * argument.  We check that address now. */
+        if (!lguest_address_ok(lg, lg->hcall->arg1, sizeof(*lg->lguest_data)))
+                return -EFAULT;
+
+        /* Having checked it, we simply set lg->lguest_data to point straight
+         * into the Launcher's memory at the right place and then use
+         * copy_to_user/from_user from now on, instead of lgread/write.  I put
+         * this in to show that I'm not immune to writing stupid
+         * optimizations. */
+        lg->lguest_data = lg->mem_base + lg->hcall->arg1;
+
+        /* We insist that the Time Stamp Counter exist and doesn't change with
+         * cpu frequency.  Some devious chip manufacturers decided that TSC
+         * changes could be handled in software.  I decided that time going
+         * backwards might be good for benchmarks, but it's bad for users.
+         *
+         * We also insist that the TSC be stable: the kernel detects unreliable
+         * TSCs for its own purposes, and we use that here. */
+        if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
+                tsc_speed = tsc_khz;
+        else
+                tsc_speed = 0;
+        if (put_user(tsc_speed, &lg->lguest_data->tsc_khz))
+                return -EFAULT;
+
+        /* The interrupt code might not like the system call vector. */
+        if (!check_syscall_vector(lg))
+                kill_guest(lg, "bad syscall vector");
+
+        return 0;
+}
+/* Now we've examined the hypercall code; our Guest can make requests.  There
+ * is one other way we can do things for the Guest, as we see in
+ * emulate_insn(). :*/
+
+/*L:030 lguest_arch_setup_regs()
+ *
+ * Most of the Guest's registers are left alone: we used get_zeroed_page() to
+ * allocate the structure, so they will be 0. */
+void lguest_arch_setup_regs(struct lguest *lg, unsigned long start)
+{
+        struct lguest_regs *regs = lg->regs;
+
+        /* There are four "segment" registers which the Guest needs to boot:
+         * The "code segment" register (cs) refers to the kernel code segment
+         * __KERNEL_CS, and the "data", "extra" and "stack" segment registers
+         * refer to the kernel data segment __KERNEL_DS.
+         *
+         * The privilege level is packed into the lower bits.  The Guest runs
+         * at privilege level 1 (GUEST_PL).*/
+        regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
+        regs->cs = __KERNEL_CS|GUEST_PL;
+
+        /* The "eflags" register contains miscellaneous flags.  Bit 1 (0x002)
+         * is supposed to always be "1".  Bit 9 (0x200) controls whether
+         * interrupts are enabled.  We always leave interrupts enabled while
+         * running the Guest. */
+        regs->eflags = 0x202;
+
+        /* The "Extended Instruction Pointer" register says where the Guest is
+         * running. */
+        regs->eip = start;
+
+        /* %esi points to our boot information, at physical address 0, so don't
+         * touch it. */
+        /* There are a couple of GDT entries the Guest expects when first
+         * booting. */
+
+        setup_guest_gdt(lg);
+}
diff --git a/drivers/lguest/switcher.S b/drivers/lguest/x86/switcher_32.S
index 7c9c230cc845..1010b90b11fc 100644
--- a/drivers/lguest/switcher.S
+++ b/drivers/lguest/x86/switcher_32.S
@@ -48,7 +48,8 @@
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/page.h>
-#include "lg.h"
+#include <asm/segment.h>
+#include <asm/lguest.h>
 
 // We mark the start of the code to copy
 // It's placed in .text tho it's never run here
@@ -132,6 +133,7 @@ ENTRY(switch_to_guest)
         // The Guest's register page has been mapped
         // Writable onto our %esp (stack) --
         // We can simply pop off all Guest regs.
+        popl    %eax
         popl    %ebx
         popl    %ecx
         popl    %edx
@@ -139,7 +141,6 @@ ENTRY(switch_to_guest)
         popl    %edi
         popl    %ebp
         popl    %gs
-        popl    %eax
         popl    %fs
         popl    %ds
         popl    %es
@@ -167,7 +168,6 @@ ENTRY(switch_to_guest)
         pushl   %es;                                                    \
         pushl   %ds;                                                    \
         pushl   %fs;                                                    \
-        pushl   %eax;                                                   \
         pushl   %gs;                                                    \
         pushl   %ebp;                                                   \
         pushl   %edi;                                                   \
@@ -175,6 +175,7 @@ ENTRY(switch_to_guest)
         pushl   %edx;                                                   \
         pushl   %ecx;                                                   \
         pushl   %ebx;                                                   \
+        pushl   %eax;                                                   \
         /* Our stack and our code are using segments                    \
          * Set in the TSS and IDT                                       \
          * Yet if we were to touch data we'd use                        \