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Commit e7a3481c authored Oct 25, 2010 by Jeremy Fitzhardinge Committed by Ingo Molnar Nov 28, 2010

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 <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 0f639a3c

arch/x86/include/asm/pvclock.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -11,6 +11,7 @@ unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
	void pvclock_read_wallclock(struct pvclock_wall_clock *wall,		void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
	struct pvclock_vcpu_time_info *vcpu,		struct pvclock_vcpu_time_info *vcpu,
	struct timespec *ts);		struct timespec *ts);
			void pvclock_resume(void);

	/*		/*
	* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,		* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,

arch/x86/kernel/pvclock.c

+5 −0

Original line number	Original line	Diff line number	Diff line
	@@ -83,6 +83,11 @@ unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src)

	static atomic64_t last_value = ATOMIC64_INIT(0);		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)		cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
	{		{
	struct pvclock_shadow_time shadow;		struct pvclock_shadow_time shadow;

arch/x86/xen/time.c

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -426,6 +426,8 @@ void xen_timer_resume(void)
	{		{
	int cpu;		int cpu;

			pvclock_resume();

	if (xen_clockevent != &xen_vcpuop_clockevent)		if (xen_clockevent != &xen_vcpuop_clockevent)
	return;		return;