On 11/26/2010 02:40 AM, Ingo Molnar wrote:
> * Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>
>> 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.
> Does not apply cleanly here - mind resending the latest version?
It rebased cleanly to 2.6.37-rc3. You can pull it from:
git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git pvclock-resume
Jeremy Fitzhardinge (1):
x86/pvclock: zero last_value on resume
arch/x86/include/asm/pvclock.h | 1 +
arch/x86/kernel/pvclock.c | 5 +++++
arch/x86/xen/time.c | 2 ++
3 files changed, 8 insertions(+), 0 deletions(-)
Thanks,
J
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 <jeremy.fitzhardinge@xxxxxxxxxx>
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index 7f7e577..31d84ac 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -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,
diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index 008b91e..42eb330 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -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;
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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