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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 B38EAC04EBF for ; Mon, 23 Sep 2019 10:44:14 +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 83B1F20835 for ; Mon, 23 Sep 2019 10:44:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 83B1F20835 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]:54752 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCLpF-0003Zq-Mo for qemu-devel@archiver.kernel.org; Mon, 23 Sep 2019 06:44:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36936) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCLnx-00030p-PJ for qemu-devel@nongnu.org; Mon, 23 Sep 2019 06:42:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iCLnv-00027x-2B for qemu-devel@nongnu.org; Mon, 23 Sep 2019 06:42:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56338) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iCLnu-00027H-TC for qemu-devel@nongnu.org; Mon, 23 Sep 2019 06:42:51 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 27D7C3175288; Mon, 23 Sep 2019 10:42:49 +0000 (UTC) Received: from work-vm (ovpn-117-213.ams2.redhat.com [10.36.117.213]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4F5F160605; Mon, 23 Sep 2019 10:42:48 +0000 (UTC) Date: Mon, 23 Sep 2019 11:42:45 +0100 From: "Dr. David Alan Gilbert" To: Jintack Lim , pbonzini@redhat.com Subject: Re: Migration failure when running nested VMs Message-ID: <20190923104245.GA2866@work-vm> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Mon, 23 Sep 2019 10:42:49 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] 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: QEMU Devel Mailing List Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Jintack Lim (incredible.tack@gmail.com) wrote: > Hi, Copying in Paolo, since he recently did work to fix nested migration - it was expected to be broken until pretty recently; but 4.1.0 qemu on 5.3 kernel is pretty new, so I think I'd expected it to work. > I'm seeing VM live migration failure when a VM is running a nested VM. > I'm using latest Linux kernel (v5.3) and QEMU (v4.1.0). I also tried > v5.2, but the result was the same. Kernel versions in L1 and L2 VM are > v4.18, but I don't think that matters. > > The symptom is that L2 VM kernel crashes in different places after > migration but the call stack is mostly related to memory management > like [1] and [2]. The kernel crash happens almost all the time. While > L2 VM gets kernel panic, L1 VM runs fine after the migration. Both L1 > and L2 VM were doing nothing during migration. > > I found a few clues about this issue. > 1) It happens with a relatively large memory for L1 (24G), but it does > not with a smaller size (3G). > > 2) Dead migration worked; when I ran "stop" command in the qemu > monitor for L1 first and did migration, migration worked always. It > also worked when I only stopped L2 VM and kept L1 live during the > migration. > > With those two clues, I guess maybe some dirty pages made by L2 are > not transferred to the destination correctly, but I'm not really sure. > > 3) It happens on Intel(R) Xeon(R) Silver 4114 CPU, but it does not on > Intel(R) Xeon(R) CPU E5-2630 v3 CPU. > > This makes me confused because I thought migrating nested state > doesn't depend on the underlying hardware.. Anyways, L1-only migration > with the large memory size (24G) works on both CPUs without any > problem. > > I would appreciate any comments/suggestions to fix this problem. Can you share the qemu command lines you're using for both L1 and L2 please ? Are there any dmesg entries around the time of the migration on either the hosts or the L1 VMs? What guest OS are you running in L1 and L2? Dave > Thanks, > Jintack > > > [1]https://paste.ubuntu.com/p/XGDKH45yt4/ > [2]https://paste.ubuntu.com/p/CpbVTXJCyc/ > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK