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xen-devel
[Xen-devel] Re: [PATCH] x86/pvclock-xen: zero last_value on resume
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To: |
"H. Peter Anvin" <hpa@xxxxxxxxx> |
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Subject: |
[Xen-devel] Re: [PATCH] x86/pvclock-xen: zero last_value on resume |
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From: |
Jeremy Fitzhardinge <jeremy@xxxxxxxx> |
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Date: |
Mon, 22 Nov 2010 12:16:43 -0800 |
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Cc: |
"Xen-devel@xxxxxxxxxxxxxxxxxxx" <Xen-devel@xxxxxxxxxxxxxxxxxxx>, kvm-devel <kvm@xxxxxxxxxxxxxxx>, Glauber Costa <glommer@xxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Linux Virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Olivier Hanesse <olivier.hanesse@xxxxxxxxx>, Avi Kivity <avi@xxxxxxxxxx>, Eelco Dolstra <e.dolstra@xxxxxxxxxx> |
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Mon, 22 Nov 2010 12:17:29 -0800 |
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On 10/26/2010 09:59 AM, Jeremy Fitzhardinge wrote:
>
> 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.
Ping? Looks like this fell through the gaps.
J
> [ I don't know if kvm needs an analogous fix or not. ]
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> Cc: Stable Kernel <stable@xxxxxxxxxx>
> Reported-by: Eelco Dolstra <e.dolstra@xxxxxxxxxx>
> Reported-by: Olivier Hanesse <olivier.hanesse@xxxxxxxxx>
> Bisected-by: Cédric Schieli <cschieli@xxxxxxxxx>
> Tested-by: Cédric Schieli <cschieli@xxxxxxxxx>
>
> 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;
>
>
>
>
>
> _______________________________________________
> Virtualization mailing list
> Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> https://lists.linux-foundation.org/mailman/listinfo/virtualization
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