From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757786Ab1IATYU (ORCPT ); Thu, 1 Sep 2011 15:24:20 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:50719 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757437Ab1IATYS (ORCPT ); Thu, 1 Sep 2011 15:24:18 -0400 Message-ID: <4E5FDBDC.2030302@codemonkey.ws> Date: Thu, 01 Sep 2011 14:24:12 -0500 From: Anthony Liguori User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110516 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: Marcelo Tosatti CC: Eric B Munson , avi@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, arnd@arndb.de, riel@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kvm-ppc@vger.kernel.org, aliguori@us.ibm.com, raharper@us.ibm.com, kvm-ia64@vger.kernel.org, Glauber Costa Subject: Re: [PATCH 0/4] Avoid soft lockup message when KVM is stopped by host References: <1314660435-23293-1-git-send-email-emunson@mgebm.net> <20110830122630.GA19450@amt.cnet> In-Reply-To: <20110830122630.GA19450@amt.cnet> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/30/2011 07:26 AM, Marcelo Tosatti wrote: > On Mon, Aug 29, 2011 at 05:27:11PM -0600, Eric B Munson wrote: >> Currently, when qemu stops a guest kernel that guest will issue a soft lockup >> message when it resumes. This set provides the ability for qemu to comminucate >> to the guest that it has been stopped. When the guest hits the watchdog on >> resume it will check if it was suspended before issuing the warning. >> >> Eric B Munson (4): >> Add flag to indicate that a vm was stopped by the host >> Add functions to check if the host has stopped the vm >> Add generic stubs for kvm stop check functions >> Add check for suspended vm in softlockup detector >> >> arch/x86/include/asm/pvclock-abi.h | 1 + >> arch/x86/include/asm/pvclock.h | 2 ++ >> arch/x86/kernel/kvmclock.c | 14 ++++++++++++++ >> include/asm-generic/pvclock.h | 14 ++++++++++++++ >> kernel/watchdog.c | 12 ++++++++++++ >> 5 files changed, 43 insertions(+), 0 deletions(-) >> create mode 100644 include/asm-generic/pvclock.h >> >> -- >> 1.7.4.1 > > How is the host supposed to set this flag? > > As mentioned previously, if you save save/restore the offset added to > kvmclock on stop/cont (and the TSC MSR, forgot to mention that), no > paravirt infrastructure is required. Which means the issue is also fixed > for older guests. IIRC, the steal time patches have some logic that basically say: if there was steal time: kick soft lockup detector I wonder if that serves this purpose provided that time spent in stop is accounted as steal time. If it isn't, perhaps it should be? Regards, Anthony Liguori > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html