From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AFA3C4360C for ; Wed, 16 Oct 2019 08:48:11 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 41D2820872 for ; Wed, 16 Oct 2019 08:48:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41D2820872 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39290 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iKeyY-0004n5-GN for qemu-devel@archiver.kernel.org; Wed, 16 Oct 2019 04:48:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48772) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iKevU-0002rA-Tk for qemu-devel@nongnu.org; Wed, 16 Oct 2019 04:45:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iKevT-0002RU-HB for qemu-devel@nongnu.org; Wed, 16 Oct 2019 04:45:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37294) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iKevT-0002QK-3b for qemu-devel@nongnu.org; Wed, 16 Oct 2019 04:44:59 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A7EAF308FBB4 for ; Wed, 16 Oct 2019 08:44:57 +0000 (UTC) Received: from redhat.com (ovpn-117-4.ams2.redhat.com [10.36.117.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4223F5D713; Wed, 16 Oct 2019 08:44:54 +0000 (UTC) From: Juan Quintela To: Peter Xu Subject: Re: [PATCH v2 3/4] apic: Use 32bit APIC ID for migration instance ID In-Reply-To: <20191016022933.7276-4-peterx@redhat.com> (Peter Xu's message of "Wed, 16 Oct 2019 10:29:32 +0800") References: <20191016022933.7276-1-peterx@redhat.com> <20191016022933.7276-4-peterx@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) Date: Wed, 16 Oct 2019 10:44:51 +0200 Message-ID: <871rvdqdto.fsf@trasno.org> MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Wed, 16 Oct 2019 08:44:57 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: quintela@redhat.com Cc: Paolo Bonzini , "Dr . David Alan Gilbert" , qemu-devel@nongnu.org, Eduardo Habkost , Igor Mammedov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Peter Xu wrote: > Migration is silently broken now with x2apic config like this: > > -smp 200,maxcpus=288,sockets=2,cores=72,threads=2 \ > -device intel-iommu,intremap=on,eim=on > > After migration, the guest kernel could hang at anything, due to > x2apic bit not migrated correctly in IA32_APIC_BASE on some vcpus, so > any operations related to x2apic could be broken then (e.g., RDMSR on > x2apic MSRs could fail because KVM would think that the vcpu hasn't > enabled x2apic at all). > > The issue is that the x2apic bit was never applied correctly for vcpus > whose ID > 255 when migrate completes, and that's because when we > migrate APIC we use the APICCommonState.id as instance ID of the > migration stream, while that's too short for x2apic. > > Let's use the newly introduced initial_apic_id for that. > > Signed-off-by: Peter Xu Reviewed-by: Juan Quintela