From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: DomU clock jumps forward then freezes after Dom0 reboot Date: Mon, 25 Oct 2010 17:21:57 -0700 Message-ID: <4CC61F25.80603@goop.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: =?UTF-8?B?Q8OpZHJpYyBTY2hpZWxp?= Cc: xen-devel List-Id: xen-devel@lists.xenproject.org On 10/24/2010 05:31 AM, C=C3=A9dric Schieli wrote: > Hello, > > I can confirm my problem reported here > http://lists.xensource.com/archives/html/xen-devel/2010-10/msg00057.htm= l > is the same. > DomU kernels affected by the migration hang are also affected by the > save/restore hang. Reverting "x86, paravirt: Add a global > synchronization point for pvclock" also fix the save/restore hang. > After doing save/reboot/restore (which led to a hang), migrating it to > a host with a longer uptime will unblock the domain, but the wallclock > will be several hours forward. Migrating back will block again. Does this help? From: Jeremy Fitzhardinge 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 diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvcloc= k.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); =20 #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_ti= me_info *src) =20 static atomic64_t last_value =3D ATOMIC64_INIT(0); =20 +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; =20 + pvclock_resume(); + if (xen_clockevent !=3D &xen_vcpuop_clockevent) return; =20