From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2 0/2] savevm odness related to kvmclock Date: Mon, 06 Dec 2010 15:10:36 +0100 Message-ID: <4CFCEEDC.6040009@redhat.com> References: <1291644227-22923-1-git-send-email-glommer@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org, avi@redhat.com, mtosatti@redhat.com To: Glauber Costa Return-path: Received: from mail-qw0-f46.google.com ([209.85.216.46]:51619 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751556Ab0LFOKg (ORCPT ); Mon, 6 Dec 2010 09:10:36 -0500 Received: by qwd7 with SMTP id 7so1296766qwd.19 for ; Mon, 06 Dec 2010 06:10:36 -0800 (PST) In-Reply-To: <1291644227-22923-1-git-send-email-glommer@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 12/06/2010 03:03 PM, Glauber Costa wrote: > Some users told me that savevm path is behaving oddly wrt kvmclock. > The first oddness is that a guarantee we never made (AFAIK) is being broken: > two consecutive "savevm" operations, with the machine stopped in between > produces different results, due to the call to KVM_GET_CLOCK ioctl. > I believe the assumption that if the vm does not run, its saveable > state won't change is fairly reasonable. Maybe we should formally > guarantee that? > > Also, this patch deals with the fact that this happens even if > kvmclock is disabled in cpuid: its savevm section is registered > nevertheless. Here, I try to register it only if it's enabled at > machine start. > > v2: improvements suggested by Paolo, and patch reordering. > > Glauber Costa (2): > Do not register kvmclock savevm section if kvmclock is disabled. > make kvmclock value idempotent for stopped machine > > cpus.c | 3 +++ > qemu-kvm-x86.c | 23 +++++++++++++++-------- > qemu-kvm.h | 3 +++ > target-i386/kvm.c | 7 +++++++ > 4 files changed, 28 insertions(+), 8 deletions(-) ACK Paolo