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=-3.8 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 C6767ECE59D for ; Wed, 16 Oct 2019 02:43:15 +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 9B7EE2086A for ; Wed, 16 Oct 2019 02:43:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B7EE2086A 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]:35320 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iKZHO-0007gI-PA for qemu-devel@archiver.kernel.org; Tue, 15 Oct 2019 22:43:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60164) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iKZGk-00079Y-F1 for qemu-devel@nongnu.org; Tue, 15 Oct 2019 22:42:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iKZGi-0002Kr-Qg for qemu-devel@nongnu.org; Tue, 15 Oct 2019 22:42:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59886) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iKZGi-0002KS-LG for qemu-devel@nongnu.org; Tue, 15 Oct 2019 22:42:32 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 884C410CC1F8 for ; Wed, 16 Oct 2019 02:42:31 +0000 (UTC) Received: from localhost (ovpn-116-20.phx2.redhat.com [10.3.116.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0801E5C1D6; Wed, 16 Oct 2019 02:42:28 +0000 (UTC) Date: Tue, 15 Oct 2019 23:42:27 -0300 From: Eduardo Habkost To: Peter Xu Subject: Re: [PATCH v2 3/4] apic: Use 32bit APIC ID for migration instance ID Message-ID: <20191016024227.GC4084@habkost.net> References: <20191016022933.7276-1-peterx@redhat.com> <20191016022933.7276-4-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191016022933.7276-4-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.65]); Wed, 16 Oct 2019 02:42:31 +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: , Cc: Paolo Bonzini , Juan Quintela , qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , Igor Mammedov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Oct 16, 2019 at 10:29:32AM +0800, 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: Eduardo Habkost -- Eduardo