From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <5523BB51.8090703@redhat.com> Date: Tue, 07 Apr 2015 13:11:13 +0200 From: Paolo Bonzini MIME-Version: 1.0 To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org CC: kvm@vger.kernel.org, Marcelo Tosatti , Andy Lutomirski , stable@vger.kernel.org Subject: Re: [PATCH] x86: vdso: fix pvclock races with task migration References: <1428000263-11892-1-git-send-email-rkrcmar@redhat.com> In-Reply-To: <1428000263-11892-1-git-send-email-rkrcmar@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: On 02/04/2015 20:44, Radim Krčmář wrote: > If we were migrated right after __getcpu, but before reading the > migration_count, we wouldn't notice that we read TSC of a different > VCPU, nor that KVM's bug made pvti invalid, as only migration_count > on source VCPU is increased. > > Change vdso instead of updating migration_count on destination. > > Fixes: 0a4e6be9ca17 ("x86: kvm: Revert "remove sched notifier for cross-cpu migrations"") > Cc: stable@vger.kernel.org > Signed-off-by: Radim Krčmář Applying this, but removing the "Fixes" tag because a guest patch cannot fix a host patch (it can work around it or complement it). Paolo