1 files changed, 245 insertions, 127 deletions

diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index eaf722fe309a..96f7d88ec7f8 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -17,13 +17,15 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
-/*P:450 This file contains the x86-specific lguest code.  It used to be all
+/*P:450
+ * This file contains the x86-specific lguest code.  It used to be all
  * mixed in with drivers/lguest/core.c but several foolhardy code slashers
  * wrestled most of the dependencies out to here in preparation for porting
  * lguest to other architectures (see what I mean by foolhardy?).
  *
  * This also contains a couple of non-obvious setup and teardown pieces which
- * were implemented after days of debugging pain. :*/
+ * were implemented after days of debugging pain.
+:*/
 #include <linux/kernel.h>
 #include <linux/start_kernel.h>
 #include <linux/string.h>
@@ -82,25 +84,33 @@ static DEFINE_PER_CPU(struct lg_cpu *, last_cpu);
  */
 static void copy_in_guest_info(struct lg_cpu *cpu, struct lguest_pages *pages)
 {
-        /* Copying all this data can be quite expensive.  We usually run the
+        /*
+         * 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. */
+         * Guest has changed.
+         */
         if (__get_cpu_var(last_cpu) != cpu || cpu->last_pages != pages) {
                 __get_cpu_var(last_cpu) = cpu;
                 cpu->last_pages = pages;
                 cpu->changed = CHANGED_ALL;
         }
 
-        /* These copies are pretty cheap, so we do them unconditionally: */
-        /* Save the current Host top-level page directory. */
+        /*
+         * 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). */
+        /*
+         * Set up the Guest's page tables to see this CPU's pages (and no
+         * other CPU's pages).
+         */
         map_switcher_in_guest(cpu, pages);
-        /* Set up the two "TSS" members which tell the CPU what stack to use
+        /*
+         * 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). */
+         * level 1).
+         */
         pages->state.guest_tss.sp1 = cpu->esp1;
         pages->state.guest_tss.ss1 = cpu->ss1;
 
@@ -125,40 +135,53 @@ static void run_guest_once(struct lg_cpu *cpu, 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 the guest-specific information into this CPU's "struct
+         * lguest_pages".
+         */
         copy_in_guest_info(cpu, pages);
 
-        /* Set the trap number to 256 (impossible value).  If we fault while
+        /*
+         * 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. */
+         * cause us to abort the Guest.
+         */
         cpu->regs->trapnum = 256;
 
-        /* Now: we push the "eflags" register on the stack, then do an "lcall".
+        /*
+         * 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 layout created by an interrupt... */
+         * exactly match the stack layout created by 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. */
+                     /*
+                      * 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
+                     /*
+                      * %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. */
+                      * directory.
+                      */
                      : "0"(pages), "1"(__pa(cpu->lg->pgdirs[cpu->cpu_pgd].pgdir))
-                     /* We tell gcc that all these registers could change,
+                     /*
+                      * We tell gcc that all these registers could change,
                       * which means we don't have to save and restore them in
-                      * the Switcher. */
+                      * the Switcher.
+                      */
                      : "memory", "%edx", "%ecx", "%edi", "%esi");
 }
 /*:*/
 
-/*M:002 There are hooks in the scheduler which we can register to tell when we
+/*M:002
+ * There are hooks in the scheduler which we can register to tell when we
  * get kicked off the CPU (preempt_notifier_register()).  This would allow us
  * to lazily disable SYSENTER which would regain some performance, and should
  * also simplify copy_in_guest_info().  Note that we'd still need to restore
@@ -166,56 +189,72 @@ static void run_guest_once(struct lg_cpu *cpu, struct lguest_pages *pages)
  *
  * We could also try using this hooks for PGE, but that might be too expensive.
  *
- * The hooks were designed for KVM, but we can also put them to good use. :*/
+ * The hooks were designed for KVM, but we can also put them to good use.
+:*/
 
-/*H:040 This is the i386-specific code to setup and run the Guest.  Interrupts
- * are disabled: we own the CPU. */
+/*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 lg_cpu *cpu)
 {
-        /* Remember the awfully-named TS bit?  If the Guest has asked to set it
+        /*
+         * 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. */
+         * uses the FPU.
+         */
         if (cpu->ts)
                 unlazy_fpu(current);
 
-        /* SYSENTER is an optimized way of doing system calls.  We can't allow
+        /*
+         * 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. */
+         * 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 return when something
+        /*
+         * Now we actually run the Guest.  It will return when something
          * interesting happens, and we can examine its registers to see what it
-         * was doing. */
+         * was doing.
+         */
         run_guest_once(cpu, lguest_pages(raw_smp_processor_id()));
 
-        /* Note that the "regs" structure contains two extra entries which are
+        /*
+         * Note that the "regs" structure 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.  */
+         * traps set.
+         */
 
          /* Restore SYSENTER if it's supposed to be on. */
          if (boot_cpu_has(X86_FEATURE_SEP))
                 wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
 
-        /* If the Guest page faulted, then the cr2 register will tell us the
+        /*
+         * 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. */
+         * cr2, or we could even move off to a different CPU.
+         */
         if (cpu->regs->trapnum == 14)
                 cpu->arch.last_pagefault = read_cr2();
-        /* Similarly, if we took a trap because the Guest used the FPU,
+        /*
+         * Similarly, if we took a trap because the Guest used the FPU,
          * we have to restore the FPU it expects to see.
          * math_state_restore() may sleep and we may even move off to
          * a different CPU. So all the critical stuff should be done
-         * before this.  */
+         * before this.
+         */
         else if (cpu->regs->trapnum == 7)
                 math_state_restore();
 }
 
-/*H:130 Now we've examined the hypercall code; our Guest can make requests.
+/*H:130
+ * Now we've examined the hypercall code; our Guest can make requests.
  * Our Guest is usually so well behaved; it never tries to do things it isn't
  * allowed to, and uses hypercalls instead.  Unfortunately, Linux's paravirtual
  * infrastructure isn't quite complete, because it doesn't contain replacements
@@ -225,26 +264,33 @@ void lguest_arch_run_guest(struct lg_cpu *cpu)
  *
  * When the Guest uses one of these instructions, we get a trap (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. */
+ * instructions and skip over it.  We return true if we did.
+ */
 static int emulate_insn(struct lg_cpu *cpu)
 {
         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. */
+        /*
+         * 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(cpu, cpu->regs->eip);
 
-        /* This must be the Guest kernel trying to do something, not userspace!
+        /*
+         * 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. */
+         * level.
+         */
         if ((cpu->regs->cs & 3) != GUEST_PL)
                 return 0;
 
         /* Decoding x86 instructions is icky. */
         insn = lgread(cpu, physaddr, u8);
 
-        /* 0x66 is an "operand prefix".  It means it's using the upper 16 bits
-           of the eax register. */
+        /*
+         * 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. */
@@ -252,8 +298,10 @@ static int emulate_insn(struct lg_cpu *cpu)
                 insn = lgread(cpu, physaddr + insnlen, u8);
         }
 
-        /* We can ignore the lower bit for the moment and decode the 4 opcodes
-         * we need to emulate. */
+        /*
+         * 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;
@@ -274,9 +322,11 @@ static int emulate_insn(struct lg_cpu *cpu)
                 return 0;
         }
 
-        /* If it was an "IN" instruction, they expect the result to be read
+        /*
+         * 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". */
+         * traditionally means "there's nothing there".
+         */
         if (in) {
                 /* Lower bit tells is whether it's a 16 or 32 bit access */
                 if (insn & 0x1)
@@ -290,7 +340,8 @@ static int emulate_insn(struct lg_cpu *cpu)
         return 1;
 }
 
-/* Our hypercalls mechanism used to be based on direct software interrupts.
+/*
+ * Our hypercalls mechanism used to be based on direct software interrupts.
  * After Anthony's "Refactor hypercall infrastructure" kvm patch, we decided to
  * change over to using kvm hypercalls.
  *
@@ -318,16 +369,20 @@ static int emulate_insn(struct lg_cpu *cpu)
  */
 static void rewrite_hypercall(struct lg_cpu *cpu)
 {
-        /* This are the opcodes we use to patch the Guest.  The opcode for "int
+        /*
+         * This are the opcodes we use to patch the Guest.  The opcode for "int
          * $0x1f" is "0xcd 0x1f" but vmcall instruction is 3 bytes long, so we
-         * complete the sequence with a NOP (0x90). */
+         * complete the sequence with a NOP (0x90).
+         */
         u8 insn[3] = {0xcd, 0x1f, 0x90};
 
         __lgwrite(cpu, guest_pa(cpu, cpu->regs->eip), insn, sizeof(insn));
-        /* The above write might have caused a copy of that page to be made
+        /*
+         * The above write might have caused a copy of that page to be made
          * (if it was read-only).  We need to make sure the Guest has
          * up-to-date pagetables.  As this doesn't happen often, we can just
-         * drop them all. */
+         * drop them all.
+         */
         guest_pagetable_clear_all(cpu);
 }
 
@@ -335,9 +390,11 @@ static bool is_hypercall(struct lg_cpu *cpu)
 {
         u8 insn[3];
 
-        /* This must be the Guest kernel trying to do something.
+        /*
+         * This must be the Guest kernel trying to do something.
          * The bottom two bits of the CS segment register are the privilege
-         * level. */
+         * level.
+         */
         if ((cpu->regs->cs & 3) != GUEST_PL)
                 return false;
 
@@ -351,86 +408,105 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu)
 {
         switch (cpu->regs->trapnum) {
         case 13: /* We've intercepted a General Protection Fault. */
-                /* Check if this was one of those annoying IN or OUT
+                /*
+                 * 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. */
+                 * back into the Guest after we've done it.
+                 */
                 if (cpu->regs->errcode == 0) {
                         if (emulate_insn(cpu))
                                 return;
                 }
-                /* If KVM is active, the vmcall instruction triggers a
-                 * General Protection Fault.  Normally it triggers an
-                 * invalid opcode fault (6): */
+                /*
+                 * If KVM is active, the vmcall instruction triggers a General
+                 * Protection Fault.  Normally it triggers an invalid opcode
+                 * fault (6):
+                 */
         case 6:
-                /* We need to check if ring == GUEST_PL and
-                 * faulting instruction == vmcall. */
+                /*
+                 * We need to check if ring == GUEST_PL and faulting
+                 * instruction == vmcall.
+                 */
                 if (is_hypercall(cpu)) {
                         rewrite_hypercall(cpu);
                         return;
                 }
                 break;
         case 14: /* We've intercepted a Page Fault. */
-                /* The Guest accessed a virtual address that wasn't mapped.
+                /*
+                 * 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. */
+                 * whether kernel or userspace code.
+                 */
                 if (demand_page(cpu, cpu->arch.last_pagefault,
                                 cpu->regs->errcode))
                         return;
 
-                /* OK, it's really not there (or not OK): the Guest needs to
+                /*
+                 * 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 LHCALL_LGUEST_INIT hypercall, so
-                 * lg->lguest_data could be NULL */
+                 * lg->lguest_data could be NULL
+                 */
                 if (cpu->lg->lguest_data &&
                     put_user(cpu->arch.last_pagefault,
                              &cpu->lg->lguest_data->cr2))
                         kill_guest(cpu, "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 the Guest doesn't want to know, we already restored the
+                 * Floating Point Unit, so we just continue without telling it.
+                 */
                 if (!cpu->ts)
                         return;
                 break;
         case 32 ... 255:
-                /* These values mean a real interrupt occurred, in which case
+                /*
+                 * 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 */
+                 * 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. */
+                /*
+                 * Our 'struct hcall_args' maps directly over our regs: we set
+                 * up the pointer now to indicate a hypercall is pending.
+                 */
                 cpu->hcall = (struct hcall_args *)cpu->regs;
                 return;
         }
 
         /* We didn't handle the trap, so it needs to go to the Guest. */
         if (!deliver_trap(cpu, cpu->regs->trapnum))
-                /* If the Guest doesn't have a handler (either it hasn't
+                /*
+                 * 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 this cryptic error message. */
+                 * it handle), it dies with this cryptic error message.
+                 */
                 kill_guest(cpu, "unhandled trap %li at %#lx (%#lx)",
                            cpu->regs->trapnum, cpu->regs->eip,
                            cpu->regs->trapnum == 14 ? cpu->arch.last_pagefault
                            : cpu->regs->errcode);
 }
 
-/* Now we can look at each of the routines this calls, in increasing order of
+/*
+ * 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. :*/
+ * duality will be complete.
+:*/
 static void adjust_pge(void *on)
 {
         if (on)
@@ -439,13 +515,16 @@ static void adjust_pge(void *on)
                 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. */
+/*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
+        /*
+         * 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.
          *
@@ -453,7 +532,8 @@ void __init lguest_arch_host_init(void)
          * 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
-         * compiled-in switcher code and the high-mapped copy we just made. */
+         * compiled-in switcher code and the high-mapped copy we just made.
+         */
         for (i = 0; i < IDT_ENTRIES; i++)
                 default_idt_entries[i] += switcher_offset();
 
@@ -468,63 +548,81 @@ void __init lguest_arch_host_init(void)
         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. */
+                /* This is a convenience pointer to make the code neater. */
                 struct lguest_ro_state *state = &pages->state;
 
-                /* The Global Descriptor Table: the Host has a different one
+                /*
+                 * 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"). */
+                 * 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
+                /*
+                 * All CPUs on the Host use the same Interrupt Descriptor
                  * Table, so we just use store_idt(), which gets this CPU's IDT
-                 * descriptor. */
+                 * descriptor.
+                 */
                 store_idt(&state->host_idt_desc);
 
-                /* The descriptors for the Guest's GDT and IDT can be filled
+                /*
+                 * 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. */
+                 * ->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
+                /*
+                 * 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. */
+                 * we start it at the end of that structure.
+                 */
                 state->guest_tss.sp0 = (long)(&pages->regs + 1);
-                /* And this is the GDT entry to use for the stack: we keep a
-                 * couple of special LGUEST entries. */
+                /*
+                 * 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
+                /*
+                 * 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". */
+                 * 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. */
+                /*
+                 * 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. */
+                /*
+                 * 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
+        /*
+         * 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. */
+         * 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
+        /*
+         * 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.
@@ -534,16 +632,21 @@ void __init lguest_arch_host_init(void)
          * 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. */
+         * 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. */
+        /*
+         * We don't need the complexity of CPUs coming and going while we're
+         * doing this.
+         */
         get_online_cpus();
         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). */
+                /*
+                 * 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, 1);
                 /* Turn off the feature in the global feature set. */
                 clear_cpu_cap(&boot_cpu_data, X86_FEATURE_PGE);
@@ -590,26 +693,32 @@ int lguest_arch_init_hypercalls(struct lg_cpu *cpu)
 {
         u32 tsc_speed;
 
-        /* The pointer to the Guest's "struct lguest_data" is the only argument.
-         * We check that address now. */
+        /*
+         * The pointer to the Guest's "struct lguest_data" is the only argument.
+         * We check that address now.
+         */
         if (!lguest_address_ok(cpu->lg, cpu->hcall->arg1,
                                sizeof(*cpu->lg->lguest_data)))
                 return -EFAULT;
 
-        /* Having checked it, we simply set lg->lguest_data to point straight
+        /*
+         * 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. */
+         * optimizations.
+         */
         cpu->lg->lguest_data = cpu->lg->mem_base + cpu->hcall->arg1;
 
-        /* We insist that the Time Stamp Counter exist and doesn't change with
+        /*
+         * 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. */
+         * 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
@@ -625,38 +734,47 @@ int lguest_arch_init_hypercalls(struct lg_cpu *cpu)
 }
 /*:*/
 
-/*L:030 lguest_arch_setup_regs()
+/*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. */
+ * allocate the structure, so they will be 0.
+ */
 void lguest_arch_setup_regs(struct lg_cpu *cpu, unsigned long start)
 {
         struct lguest_regs *regs = cpu->regs;
 
-        /* There are four "segment" registers which the Guest needs to boot:
+        /*
+         * 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).*/
+         * 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)
+        /*
+         * 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. */
+         * running the Guest.
+         */
         regs->eflags = X86_EFLAGS_IF | 0x2;
 
-        /* The "Extended Instruction Pointer" register says where the Guest is
-         * running. */
+        /*
+         * 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. */
+        /*
+         * %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. */
+        /* There are a couple of GDT entries the Guest expects at boot. */
         setup_guest_gdt(cpu);
 }