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lguest: documentation update

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Went through the documentation doing typo and content fixes.  This
patch contains only comment and whitespace changes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2007-10-25 15:02:50 +10:00
parent 568a17ffce
commit e1e72965ec
16 changed files with 414 additions and 266 deletions
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37
drivers/lguest/interrupts_and_traps.c
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@@ -92,8 +92,8 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
/* 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: the Guest copies
* it back in "lguest_iret". */
* Guest's "irq_enabled" field into the eflags word: we saw the Guest
* copy it back in "lguest_iret". */
eflags = lg->regs->eflags;
if (get_user(irq_enable, &lg->lguest_data->irq_enabled) == 0
&& !(irq_enable & X86_EFLAGS_IF))
@@ -124,7 +124,7 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
kill_guest(lg, "Disabling interrupts");
}
/*H:200
/*H:205
* Virtual Interrupts.
*
* maybe_do_interrupt() gets called before every entry to the Guest, to see if
@@ -256,19 +256,21 @@ int deliver_trap(struct lguest *lg, unsigned int num)
* bogus one in): if we fail here, the Guest will be killed. */
if (!idt_present(lg->arch.idt[num].a, lg->arch.idt[num].b))
return 0;
set_guest_interrupt(lg, lg->arch.idt[num].a, lg->arch.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;
}
/*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 (trap 128).
* Particularly because Guest userspace system calls are traps (usually trap
* 128).
*
* So we'd like to set up the IDT to tell the CPU to deliver traps directly
* into the Guest. This is possible, but the complexities cause the size of
* this file to double! However, 150 lines of code is worth writing for taking
* system calls down from 1750ns to 270ns. Plus, if lguest didn't do it, all
* the other hypervisors would tease it.
* the other hypervisors would beat it up at lunchtime.
*
* This routine indicates if a particular trap number could be delivered
* directly. */
@@ -331,7 +333,7 @@ void pin_stack_pages(struct lguest *lg)
* change stacks on each context switch. */
void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages)
{
/* You are not allowd have a stack segment with privilege level 0: bad
/* You are not allowed have a stack segment with privilege level 0: bad
* Guest! */
if ((seg & 0x3) != GUEST_PL)
kill_guest(lg, "bad stack segment %i", seg);
@@ -350,7 +352,7 @@ void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages)
* 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 our entry in "struct lguest": */
* transfers it into the entry in "struct lguest": */
static void set_trap(struct lguest *lg, struct desc_struct *trap,
unsigned int num, u32 lo, u32 hi)
{
@@ -456,6 +458,18 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
}
}
/*H:200
* The Guest Clock.
*
* There are two sources of virtual interrupts. We saw one in lguest_user.c:
* the Launcher sending interrupts for virtual devices. The other is the Guest
* timer interrupt.
*
* The Guest uses the LHCALL_SET_CLOCKEVENT hypercall to tell us how long to
* 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". */
void guest_set_clockevent(struct lguest *lg, unsigned long delta)
{
ktime_t expires;
@@ -466,20 +480,27 @@ void guest_set_clockevent(struct lguest *lg, unsigned long delta)
return;
}
/* 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. */
expires = ktime_add_ns(ktime_get_real(), delta);
hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS);
}
/* This is the function called when the Guest's timer expires. */
static enum hrtimer_restart clockdev_fn(struct hrtimer *timer)
{
struct lguest *lg = container_of(timer, struct lguest, hrt);
/* Remember the first interrupt is the timer interrupt. */
set_bit(0, lg->irqs_pending);
/* If the Guest is actually stopped, we need to wake it up. */
if (lg->halted)
wake_up_process(lg->tsk);
return HRTIMER_NORESTART;
}
/* This sets up the timer for this Guest. */
void init_clockdev(struct lguest *lg)
{
hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS);