Make hypercalls arch-independent.

Clean up the hypercall code to make the code in hypercalls.c
architecture independent. First process the common hypercalls and
then call lguest_arch_do_hcall() if the call hasn't been handled.
Rename struct hcall_ring to hcall_args.

This patch requires the previous patch which reorganize the layout of
struct lguest_regs on i386 so they match the layout of struct
hcall_args.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

3 files changed, 94 insertions, 76 deletions

diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index 0175a9f03347..2859a7687288 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;
@@ -59,7 +55,7 @@ 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);
@@ -71,55 +67,47 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
                  * 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);
+                args->arg0 = bind_dma(lg, args->arg1, args->arg2,
+                                     args->arg3 >> 8, args->arg3 & 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);
+                send_dma(lg, args->arg1, args->arg2);
                 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, mkgpte(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;
         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 +122,9 @@ 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 +139,16 @@ 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])) {
@@ -182,41 +167,16 @@ 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.  We check that address now. */
-        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;
-        }
-
-        /* 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->regs->edx;
 
         /* The Guest tells us where we're not to deliver interrupts by putting
          * the range of addresses into "struct lguest_data". */
@@ -224,8 +184,7 @@ static void initialize(struct lguest *lg)
             || 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))
+            || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem))
                 kill_guest(lg, "bad guest page %p", lg->lguest_data);
 
         /* We write the current time into the Guest's data page once now. */
@@ -237,9 +196,6 @@ static void initialize(struct lguest *lg)
          * 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:100
  * Hypercalls
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 662994b776cc..00c869bd9f79 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -107,7 +107,7 @@ struct lguest
         u8 ss1;
 
         /* If a hypercall was asked for, this points to the arguments. */
-        struct lguest_regs *hcall;
+        struct hcall_args *hcall;
 
         /* Do we need to stop what we're doing and return to userspace? */
         int break_out;
@@ -197,6 +197,8 @@ 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);
 
 /* <arch>/switcher.S: */
 extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index 0cc251cbc72a..2ef64a2734d3 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -323,7 +323,9 @@ void lguest_arch_handle_trap(struct lguest *lg)
                 cond_resched();
                 return;
         case LGUEST_TRAP_ENTRY:
-                lg->hcall = lg->regs;
+                /* 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;
         }
 
@@ -475,3 +477,61 @@ void __exit lguest_arch_host_fini(void)
         }
         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;
+
+        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(). :*/