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.
[ I don't know if kvm needs an analogous fix or not. ] Signed-off-by: Jeremy Fitzhardinge <[email protected]> Cc: Stable Kernel <[email protected]> Reported-by: Eelco Dolstra <[email protected]> Reported-by: Olivier Hanesse <[email protected]> Bisected-by: Cédric Schieli <[email protected]> Tested-by: Cédric Schieli <[email protected]> diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index cd02f32..6226870 100644 --- a/arch/x86/include/asm/pvclock.h +++ b/arch/x86/include/asm/pvclock.h @@ -11,5 +11,6 @@ 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); #endif /* _ASM_X86_PVCLOCK_H */ diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 239427c..a4f07c1 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -120,6 +120,11 @@ 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; diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index b2bb5aa..5da5e53 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -426,6 +426,8 @@ void xen_timer_resume(void) { int cpu; + pvclock_resume(); + if (xen_clockevent != &xen_vcpuop_clockevent) return;
From 29acbb4e1d93e719250648db1ce8c7a24144fd86 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge <[email protected]> Date: Mon, 25 Oct 2010 16:53:46 -0700 Subject: [PATCH] x86/pvclock: zero last_value on resume 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 <[email protected]> Cc: Stable Kernel <[email protected]> Reported-by: Eelco Dolstra <[email protected]> Reported-by: Olivier Hanesse <[email protected]> Bisected-by: Cédric Schieli <[email protected]> Tested-by: Cédric Schieli <[email protected]> diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index cd02f32..6226870 100644 --- a/arch/x86/include/asm/pvclock.h +++ b/arch/x86/include/asm/pvclock.h @@ -11,5 +11,6 @@ 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); #endif /* _ASM_X86_PVCLOCK_H */ diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 239427c..a4f07c1 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -120,6 +120,11 @@ 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; diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index b2bb5aa..5da5e53 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -426,6 +426,8 @@ void xen_timer_resume(void) { int cpu; + pvclock_resume(); + if (xen_clockevent != &xen_vcpuop_clockevent) return;
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