1 files changed, 191 insertions, 97 deletions

diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 0e9067b0d507..18648180db02 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -1,4 +1,5 @@
-/*P:800 Interrupts (traps) are complicated enough to earn their own file.
+/*P:800
+ * Interrupts (traps) are complicated enough to earn their own file.
  * There are three classes of interrupts:
  *
  * 1) Real hardware interrupts which occur while we're running the Guest,
@@ -10,7 +11,8 @@
  * just like real hardware would deliver them.  Traps from the Guest can be set
  * up to go directly back into the Guest, but sometimes the Host wants to see
  * them first, so we also have a way of "reflecting" them into the Guest as if
- * they had been delivered to it directly. :*/
+ * they had been delivered to it directly.
+:*/
 #include <linux/uaccess.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
@@ -26,8 +28,10 @@ static unsigned long idt_address(u32 lo, u32 hi)
         return (lo & 0x0000FFFF) | (hi & 0xFFFF0000);
 }
 
-/* The "type" of the interrupt handler is a 4 bit field: we only support a
- * couple of types. */
+/*
+ * The "type" of the interrupt handler is a 4 bit field: we only support a
+ * couple of types.
+ */
 static int idt_type(u32 lo, u32 hi)
 {
         return (hi >> 8) & 0xF;
@@ -39,8 +43,10 @@ static bool idt_present(u32 lo, u32 hi)
         return (hi & 0x8000);
 }
 
-/* We need a helper to "push" a value onto the Guest's stack, since that's a
- * big part of what delivering an interrupt does. */
+/*
+ * We need a helper to "push" a value onto the Guest's stack, since that's a
+ * big part of what delivering an interrupt does.
+ */
 static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
 {
         /* Stack grows upwards: move stack then write value. */
@@ -48,7 +54,8 @@ static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
         lgwrite(cpu, *gstack, u32, val);
 }
 
-/*H:210 The set_guest_interrupt() routine actually delivers the interrupt or
+/*H:210
+ * The set_guest_interrupt() routine actually delivers the interrupt or
  * trap.  The mechanics of delivering traps and interrupts to the Guest are the
  * same, except some traps have an "error code" which gets pushed onto the
  * stack as well: the caller tells us if this is one.
@@ -59,7 +66,8 @@ static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
  *
  * We set up the stack just like the CPU does for a real interrupt, so it's
  * identical for the Guest (and the standard "iret" instruction will undo
- * it). */
+ * it).
+ */
 static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
                                 bool has_err)
 {
@@ -67,20 +75,26 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
         u32 eflags, ss, irq_enable;
         unsigned long virtstack;
 
-        /* There are two cases for interrupts: one where the Guest is already
+        /*
+         * 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
-         * userspace.  We check the privilege level to find out. */
+         * userspace.  We check the privilege level to find out.
+         */
         if ((cpu->regs->ss&0x3) != GUEST_PL) {
-                /* The Guest told us their kernel stack with the SET_STACK
-                 * hypercall: both the virtual address and the segment */
+                /*
+                 * The Guest told us their kernel stack with the SET_STACK
+                 * hypercall: both the virtual address and the segment.
+                 */
                 virtstack = cpu->esp1;
                 ss = cpu->ss1;
 
                 origstack = gstack = guest_pa(cpu, virtstack);
-                /* We push the old stack segment and pointer onto the new
+                /*
+                 * 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
-                 * levels and expect these here. */
+                 * levels and expect these here.
+                 */
                 push_guest_stack(cpu, &gstack, cpu->regs->ss);
                 push_guest_stack(cpu, &gstack, cpu->regs->esp);
         } else {
@@ -91,18 +105,22 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
                 origstack = gstack = guest_pa(cpu, virtstack);
         }
 
-        /* Remember that we never let the Guest actually disable interrupts, so
+        /*
+         * Remember that we never let the Guest actually disable interrupts, so
          * the "Interrupt Flag" bit is always set.  We copy that bit from the
          * Guest's "irq_enabled" field into the eflags word: we saw the Guest
-         * copy it back in "lguest_iret". */
+         * copy it back in "lguest_iret".
+         */
         eflags = cpu->regs->eflags;
         if (get_user(irq_enable, &cpu->lg->lguest_data->irq_enabled) == 0
             && !(irq_enable & X86_EFLAGS_IF))
                 eflags &= ~X86_EFLAGS_IF;
 
-        /* An interrupt is expected to push three things on the stack: the old
+        /*
+         * An interrupt is expected to push three things on the stack: the old
          * "eflags" word, the old code segment, and the old instruction
-         * pointer. */
+         * pointer.
+         */
         push_guest_stack(cpu, &gstack, eflags);
         push_guest_stack(cpu, &gstack, cpu->regs->cs);
         push_guest_stack(cpu, &gstack, cpu->regs->eip);
@@ -111,15 +129,19 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
         if (has_err)
                 push_guest_stack(cpu, &gstack, cpu->regs->errcode);
 
-        /* Now we've pushed all the old state, we change the stack, the code
-         * segment and the address to execute. */
+        /*
+         * Now we've pushed all the old state, we change the stack, the code
+         * segment and the address to execute.
+         */
         cpu->regs->ss = ss;
         cpu->regs->esp = virtstack + (gstack - origstack);
         cpu->regs->cs = (__KERNEL_CS|GUEST_PL);
         cpu->regs->eip = idt_address(lo, hi);
 
-        /* There are two kinds of interrupt handlers: 0xE is an "interrupt
-         * gate" which expects interrupts to be disabled on entry. */
+        /*
+         * There are two kinds of interrupt handlers: 0xE is an "interrupt
+         * gate" which expects interrupts to be disabled on entry.
+         */
         if (idt_type(lo, hi) == 0xE)
                 if (put_user(0, &cpu->lg->lguest_data->irq_enabled))
                         kill_guest(cpu, "Disabling interrupts");
@@ -130,7 +152,8 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
  *
  * interrupt_pending() returns the first pending interrupt which isn't blocked
  * by the Guest.  It is called before every entry to the Guest, and just before
- * we go to sleep when the Guest has halted itself. */
+ * we go to sleep when the Guest has halted itself.
+ */
 unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more)
 {
         unsigned int irq;
@@ -140,8 +163,10 @@ unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more)
         if (!cpu->lg->lguest_data)
                 return LGUEST_IRQS;
 
-        /* Take our "irqs_pending" array and remove any interrupts the Guest
-         * wants blocked: the result ends up in "blk". */
+        /*
+         * Take our "irqs_pending" array and remove any interrupts the Guest
+         * wants blocked: the result ends up in "blk".
+         */
         if (copy_from_user(&blk, cpu->lg->lguest_data->blocked_interrupts,
                            sizeof(blk)))
                 return LGUEST_IRQS;
@@ -154,16 +179,20 @@ unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more)
         return irq;
 }
 
-/* This actually diverts the Guest to running an interrupt handler, once an
- * interrupt has been identified by interrupt_pending(). */
+/*
+ * This actually diverts the Guest to running an interrupt handler, once an
+ * interrupt has been identified by interrupt_pending().
+ */
 void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
 {
         struct desc_struct *idt;
 
         BUG_ON(irq >= LGUEST_IRQS);
 
-        /* They may be in the middle of an iret, where they asked us never to
-         * deliver interrupts. */
+        /*
+         * They may be in the middle of an iret, where they asked us never to
+         * deliver interrupts.
+         */
         if (cpu->regs->eip >= cpu->lg->noirq_start &&
            (cpu->regs->eip < cpu->lg->noirq_end))
                 return;
@@ -187,29 +216,37 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
                 }
         }
 
-        /* Look at the IDT entry the Guest gave us for this interrupt.  The
+        /*
+         * 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. */
+         * over them.
+         */
         idt = &cpu->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. */
                 clear_bit(irq, cpu->irqs_pending);
-                /* set_guest_interrupt() takes the interrupt descriptor and a
+                /*
+                 * set_guest_interrupt() takes the interrupt descriptor and a
                  * flag to say whether this interrupt pushes an error code onto
-                 * the stack as well: virtual interrupts never do. */
+                 * the stack as well: virtual interrupts never do.
+                 */
                 set_guest_interrupt(cpu, idt->a, idt->b, false);
         }
 
-        /* Every time we deliver an interrupt, we update the timestamp in the
+        /*
+         * Every time we deliver an interrupt, we update the timestamp in the
          * Guest's lguest_data struct.  It would be better for the Guest if we
          * did this more often, but it can actually be quite slow: doing it
          * here is a compromise which means at least it gets updated every
-         * timer interrupt. */
+         * timer interrupt.
+         */
         write_timestamp(cpu);
 
-        /* If there are no other interrupts we want to deliver, clear
-         * the pending flag. */
+        /*
+         * If there are no other interrupts we want to deliver, clear
+         * the pending flag.
+         */
         if (!more)
                 put_user(0, &cpu->lg->lguest_data->irq_pending);
 }
@@ -217,24 +254,29 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
 /* And this is the routine when we want to set an interrupt for the Guest. */
 void set_interrupt(struct lg_cpu *cpu, unsigned int irq)
 {
-        /* Next time the Guest runs, the core code will see if it can deliver
-         * this interrupt. */
+        /*
+         * Next time the Guest runs, the core code will see if it can deliver
+         * this interrupt.
+         */
         set_bit(irq, cpu->irqs_pending);
 
-        /* Make sure it sees it; it might be asleep (eg. halted), or
-         * running the Guest right now, in which case kick_process()
-         * will knock it out. */
+        /*
+         * Make sure it sees it; it might be asleep (eg. halted), or running
+         * the Guest right now, in which case kick_process() will knock it out.
+         */
         if (!wake_up_process(cpu->tsk))
                 kick_process(cpu->tsk);
 }
 /*:*/
 
-/* Linux uses trap 128 for system calls.  Plan9 uses 64, and Ron Minnich sent
+/*
+ * 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. */
+ * userbase.  Oh well.
+ */
 static bool could_be_syscall(unsigned int num)
 {
         /* Normal Linux SYSCALL_VECTOR or reserved vector? */
@@ -274,9 +316,11 @@ void free_interrupts(void)
                 clear_bit(syscall_vector, used_vectors);
 }
 
-/*H:220 Now we've got the routines to deliver interrupts, delivering traps like
+/*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 traps
- * should have error codes: */
+ * should have error codes:
+ */
 static bool has_err(unsigned int trap)
 {
         return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
@@ -285,13 +329,17 @@ static bool has_err(unsigned int trap)
 /* deliver_trap() returns true if it could deliver the trap. */
 bool deliver_trap(struct lg_cpu *cpu, 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. */
+        /*
+         * 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(cpu->arch.idt))
                 return false;
 
-        /* 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. */
+        /*
+         * 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(cpu->arch.idt[num].a, cpu->arch.idt[num].b))
                 return false;
         set_guest_interrupt(cpu, cpu->arch.idt[num].a,
@@ -299,7 +347,8 @@ bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
         return true;
 }
 
-/*H:250 Here's the hard part: returning to the Host every time a trap happens
+/*H:250
+ * Here's the hard part: returning to the Host every time a trap happens
  * and then calling deliver_trap() and re-entering the Guest is slow.
  * Particularly because Guest userspace system calls are traps (usually trap
  * 128).
@@ -311,69 +360,87 @@ bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
  * the other hypervisors would beat it up at lunchtime.
  *
  * This routine indicates if a particular trap number could be delivered
- * directly. */
+ * directly.
+ */
 static bool direct_trap(unsigned int num)
 {
-        /* Hardware interrupts don't go to the Guest at all (except system
-         * call). */
+        /*
+         * Hardware interrupts don't go to the Guest at all (except system
+         * call).
+         */
         if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num))
                 return false;
 
-        /* The Host needs to see page faults (for shadow paging and to save the
+        /*
+         * 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), invalid opcode fault (kvm hcall),
-         * and of course, the hypercall trap. */
+         * and of course, the hypercall trap.
+         */
         return num != 14 && num != 13 && num != 7 &&
                         num != 6 && num != LGUEST_TRAP_ENTRY;
 }
 /*:*/
 
-/*M:005 The Guest has the ability to turn its interrupt gates into trap gates,
+/*M:005
+ * The Guest has the ability to turn its interrupt gates into trap gates,
  * if it is careful.  The Host will let trap gates can go directly to the
  * Guest, but the Guest needs the interrupts atomically disabled for an
  * interrupt gate.  It can do this by pointing the trap gate at instructions
- * within noirq_start and noirq_end, where it can safely disable interrupts. */
+ * within noirq_start and noirq_end, where it can safely disable interrupts.
+ */
 
-/*M:006 The Guests do not use the sysenter (fast system call) instruction,
+/*M:006
+ * The Guests do not use the sysenter (fast system call) instruction,
  * because it's hardcoded to enter privilege level 0 and so can't go direct.
  * It's about twice as fast as the older "int 0x80" system call, so it might
  * still be worthwhile to handle it in the Switcher and lcall down to the
  * Guest.  The sysenter semantics are hairy tho: search for that keyword in
- * entry.S :*/
+ * entry.S
+:*/
 
-/*H:260 When we make traps go directly into the Guest, we need to make sure
+/*H:260
+ * When we make traps go directly into the Guest, we need to make sure
  * the kernel stack is valid (ie. mapped in the page tables).  Otherwise, the
  * CPU trying to deliver the trap will fault while trying to push the interrupt
  * words on the stack: this is called a double fault, and it forces us to kill
  * the Guest.
  *
- * Which is deeply unfair, because (literally!) it wasn't the Guests' fault. */
+ * Which is deeply unfair, because (literally!) it wasn't the Guests' fault.
+ */
 void pin_stack_pages(struct lg_cpu *cpu)
 {
         unsigned int i;
 
-        /* Depending on the CONFIG_4KSTACKS option, the Guest can have one or
-         * two pages of stack space. */
+        /*
+         * Depending on the CONFIG_4KSTACKS option, the Guest can have one or
+         * two pages of stack space.
+         */
         for (i = 0; i < cpu->lg->stack_pages; i++)
-                /* The stack grows *upwards*, so the address we're given is the
+                /*
+                 * The stack grows *upwards*, so the address we're given is the
                  * start of the page after the kernel stack.  Subtract one to
                  * get back onto the first stack page, and keep subtracting to
-                 * get to the rest of the stack pages. */
+                 * get to the rest of the stack pages.
+                 */
                 pin_page(cpu, cpu->esp1 - 1 - i * PAGE_SIZE);
 }
 
-/* Direct traps also mean that we need to know whenever the Guest wants to use
+/*
+ * Direct traps also mean that we need to know whenever the Guest wants to use
  * a different kernel stack, so we can change the IDT entries to use that
  * stack.  The IDT entries expect a virtual address, so unlike most addresses
  * the Guest gives us, the "esp" (stack pointer) value here is virtual, not
  * physical.
  *
  * In Linux each process has its own kernel stack, so this happens a lot: we
- * change stacks on each context switch. */
+ * change stacks on each context switch.
+ */
 void guest_set_stack(struct lg_cpu *cpu, u32 seg, u32 esp, unsigned int pages)
 {
-        /* You are not allowed have a stack segment with privilege level 0: bad
-         * Guest! */
+        /*
+         * You're not allowed a stack segment with privilege level 0: bad Guest!
+         */
         if ((seg & 0x3) != GUEST_PL)
                 kill_guest(cpu, "bad stack segment %i", seg);
         /* We only expect one or two stack pages. */
@@ -387,11 +454,15 @@ void guest_set_stack(struct lg_cpu *cpu, u32 seg, u32 esp, unsigned int pages)
         pin_stack_pages(cpu);
 }
 
-/* All this reference to mapping stacks leads us neatly into the other complex
- * part of the Host: page table handling. */
+/*
+ * All this reference to mapping stacks leads us neatly into the other complex
+ * part of the Host: page table handling.
+ */
 
-/*H:235 This is the routine which actually checks the Guest's IDT entry and
- * transfers it into the entry in "struct lguest": */
+/*H:235
+ * This is the routine which actually checks the Guest's IDT entry and
+ * transfers it into the entry in "struct lguest":
+ */
 static void set_trap(struct lg_cpu *cpu, struct desc_struct *trap,
                      unsigned int num, u32 lo, u32 hi)
 {
@@ -407,30 +478,38 @@ static void set_trap(struct lg_cpu *cpu, struct desc_struct *trap,
         if (type != 0xE && type != 0xF)
                 kill_guest(cpu, "bad IDT type %i", type);
 
-        /* We only copy the handler address, present bit, privilege level and
+        /*
+         * We only copy the handler address, present bit, privilege level and
          * type.  The privilege level controls where the trap can be triggered
          * manually with an "int" instruction.  This is usually GUEST_PL,
-         * except for system calls which userspace can use. */
+         * except for system calls which userspace can use.
+         */
         trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF);
         trap->b = (hi&0xFFFFEF00);
 }
 
-/*H:230 While we're here, dealing with delivering traps and interrupts to the
+/*H:230
+ * While we're here, dealing with delivering traps and interrupts to the
  * Guest, we might as well complete the picture: how the Guest tells us where
  * it wants them to go.  This would be simple, except making traps fast
  * requires some tricks.
  *
  * We saw the Guest setting Interrupt Descriptor Table (IDT) entries with the
- * LHCALL_LOAD_IDT_ENTRY hypercall before: that comes here. */
+ * LHCALL_LOAD_IDT_ENTRY hypercall before: that comes here.
+ */
 void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int num, u32 lo, u32 hi)
 {
-        /* Guest never handles: NMI, doublefault, spurious interrupt or
-         * hypercall.  We ignore when it tries to set them. */
+        /*
+         * Guest never handles: NMI, doublefault, spurious interrupt or
+         * hypercall.  We ignore when it tries to set them.
+         */
         if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY)
                 return;
 
-        /* Mark the IDT as changed: next time the Guest runs we'll know we have
-         * to copy this again. */
+        /*
+         * Mark the IDT as changed: next time the Guest runs we'll know we have
+         * to copy this again.
+         */
         cpu->changed |= CHANGED_IDT;
 
         /* Check that the Guest doesn't try to step outside the bounds. */
@@ -440,9 +519,11 @@ void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int num, u32 lo, u32 hi)
                 set_trap(cpu, &cpu->arch.idt[num], num, lo, hi);
 }
 
-/* The default entry for each interrupt points into the Switcher routines which
+/*
+ * The default entry for each interrupt points into the Switcher routines which
  * simply return to the Host.  The run_guest() loop will then call
- * deliver_trap() to bounce it back into the Guest. */
+ * deliver_trap() to bounce it back into the Guest.
+ */
 static void default_idt_entry(struct desc_struct *idt,
                               int trap,
                               const unsigned long handler,
@@ -451,13 +532,17 @@ static void default_idt_entry(struct desc_struct *idt,
         /* A present interrupt gate. */
         u32 flags = 0x8e00;
 
-        /* Set the privilege level on the entry for the hypercall: this allows
-         * the Guest to use the "int" instruction to trigger it. */
+        /*
+         * Set the privilege level on the entry for the hypercall: this allows
+         * the Guest to use the "int" instruction to trigger it.
+         */
         if (trap == LGUEST_TRAP_ENTRY)
                 flags |= (GUEST_PL << 13);
         else if (base)
-                /* Copy priv. level from what Guest asked for.  This allows
-                 * debug (int 3) traps from Guest userspace, for example. */
+                /*
+                 * Copy privilege level from what Guest asked for.  This allows
+                 * debug (int 3) traps from Guest userspace, for example.
+                 */
                 flags |= (base->b & 0x6000);
 
         /* Now pack it into the IDT entry in its weird format. */
@@ -475,16 +560,20 @@ void setup_default_idt_entries(struct lguest_ro_state *state,
                 default_idt_entry(&state->guest_idt[i], i, def[i], NULL);
 }
 
-/*H:240 We don't use the IDT entries in the "struct lguest" directly, instead
+/*H:240
+ * We don't use the IDT entries in the "struct lguest" directly, instead
  * we copy them into the IDT which we've set up for Guests on this CPU, just
- * before we run the Guest.  This routine does that copy. */
+ * before we run the Guest.  This routine does that copy.
+ */
 void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
                 const unsigned long *def)
 {
         unsigned int i;
 
-        /* We can simply copy the direct traps, otherwise we use the default
-         * ones in the Switcher: they will return to the Host. */
+        /*
+         * 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 < ARRAY_SIZE(cpu->arch.idt); i++) {
                 const struct desc_struct *gidt = &cpu->arch.idt[i];
 
@@ -492,14 +581,16 @@ void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
                 if (!direct_trap(i))
                         continue;
 
-                /* Only trap gates (type 15) can go direct to the Guest.
+                /*
+                 * 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 it can't go direct, we still need to copy the priv. level:
                  * they might want to give userspace access to a software
-                 * interrupt. */
+                 * interrupt.
+                 */
                 if (idt_type(gidt->a, gidt->b) == 0xF)
                         idt[i] = *gidt;
                 else
@@ -518,7 +609,8 @@ void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
  * the next timer interrupt (in nanoseconds).  We use the high-resolution timer
  * infrastructure to set a callback at that time.
  *
- * 0 means "turn off the clock". */
+ * 0 means "turn off the clock".
+ */
 void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta)
 {
         ktime_t expires;
@@ -529,9 +621,11 @@ void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta)
                 return;
         }
 
-        /* We use wallclock time here, so the Guest might not be running for
+        /*
+         * We use wallclock time here, so the Guest might not be running for
          * all the time between now and the timer interrupt it asked for.  This
-         * is almost always the right thing to do. */
+         * is almost always the right thing to do.
+         */
         expires = ktime_add_ns(ktime_get_real(), delta);
         hrtimer_start(&cpu->hrt, expires, HRTIMER_MODE_ABS);
 }