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x86/pvclock: Zero last_value on resume

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If the guest domain has been suspend/resumed or migrated, then the
system clock backing the pvclock clocksource may revert to a smaller
value (ie, can be non-monotonic across the migration/save-restore).

Make sure we zero last_value in that case so that the domain
continues to see clock updates.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge 2010-10-25 16:53:46 -07:00 committed by Ingo Molnar
parent 0f639a3c5c
commit e7a3481c02
3 changed files with 8 additions and 0 deletions
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1
arch/x86/include/asm/pvclock.h
View File

@ -11,6 +11,7 @@ unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
struct pvclock_vcpu_time_info *vcpu,
struct timespec *ts);
void pvclock_resume(void);
/*
* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,

5
arch/x86/kernel/pvclock.c
View File

@ -83,6 +83,11 @@ unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src)
static atomic64_t last_value = ATOMIC64_INIT(0);
void pvclock_resume(void)
{
atomic64_set(&last_value, 0);
}
cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
{
struct pvclock_shadow_time shadow;

2
arch/x86/xen/time.c
View File

@ -426,6 +426,8 @@ void xen_timer_resume(void)
{
int cpu;
pvclock_resume();
if (xen_clockevent != &xen_vcpuop_clockevent)
return;