From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752211Ab0KZW3n (ORCPT ); Fri, 26 Nov 2010 17:29:43 -0500 Received: from claw.goop.org ([74.207.240.146]:32905 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751778Ab0KZW3m (ORCPT ); Fri, 26 Nov 2010 17:29:42 -0500 Message-ID: <4CF034D4.70005@goop.org> Date: Fri, 26 Nov 2010 14:29:40 -0800 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.12) Gecko/20101103 Fedora/1.0-0.33.b2pre.fc14 Lightning/1.0b3pre Thunderbird/3.1.6 MIME-Version: 1.0 To: Ingo Molnar CC: "H. Peter Anvin" , "Xen-devel@lists.xensource.com" , kvm-devel , Glauber Costa , the arch/x86 maintainers , Linux Kernel Mailing List , Linux Virtualization , Olivier Hanesse , Avi Kivity , Eelco Dolstra , Thomas Gleixner Subject: Re: [PATCH] x86/pvclock-xen: zero last_value on resume References: <4CC708DE.1070000@goop.org> <4CEACFAB.90503@goop.org> <20101126104047.GA9798@elte.hu> In-Reply-To: <20101126104047.GA9798@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/26/2010 02:40 AM, Ingo Molnar wrote: > * Jeremy Fitzhardinge 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 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;