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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 A94F8C433B4 for ; Wed, 12 May 2021 16:49:13 +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 ECCDB61183 for ; Wed, 12 May 2021 16:49:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECCDB61183 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]:38678 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lgs2p-0001ZY-JQ for qemu-devel@archiver.kernel.org; Wed, 12 May 2021 12:49:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48532) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lgrxC-0004BY-Fl for qemu-devel@nongnu.org; Wed, 12 May 2021 12:43:23 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44735) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lgrx6-0003pg-VM for qemu-devel@nongnu.org; Wed, 12 May 2021 12:43:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620837795; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Pg4WWR11+C6QB+MmPuxnZ598tg/zCDGTZGEyuSvhc/Y=; b=CGXrmtpzzGDgER6whAVei1ETUnQ7hf7y2vlD+IPTwQ/86fRTa+6tBPnJoJclo0GWzL2+fF 3x1iXYIoOQWdwgafil0PyC63JfcOm4r6Iyrz2oBX+wQCkZXkHtjCDBJKDgfoehIfZacCSh cW4CA3jFuOxhCVKYR6O7JEppFzKbcSY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-453-K9WShe7NP7eNzkbdH3uexQ-1; Wed, 12 May 2021 12:43:12 -0400 X-MC-Unique: K9WShe7NP7eNzkbdH3uexQ-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 058B31012D92; Wed, 12 May 2021 16:43:11 +0000 (UTC) Received: from localhost (ovpn-115-51.ams2.redhat.com [10.36.115.51]) by smtp.corp.redhat.com (Postfix) with ESMTP id 82E1460CE6; Wed, 12 May 2021 16:42:59 +0000 (UTC) Date: Wed, 12 May 2021 17:42:58 +0100 From: Stefan Hajnoczi To: Steve Sistare Subject: Re: [PATCH V3 00/22] Live Update Message-ID: References: <1620390320-301716-1-git-send-email-steven.sistare@oracle.com> MIME-Version: 1.0 In-Reply-To: <1620390320-301716-1-git-send-email-steven.sistare@oracle.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FF8oNhgXYx8kkWYd" Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: "Daniel P. Berrange" , "Michael S. Tsirkin" , Jason Zeng , Alex =?iso-8859-1?Q?Benn=E9e?= , Juan Quintela , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Alex Williamson , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Paolo Bonzini , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Markus Armbruster Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --FF8oNhgXYx8kkWYd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, May 07, 2021 at 05:24:58AM -0700, Steve Sistare wrote: > Provide the cprsave and cprload commands for live update. These save and > restore VM state, with minimal guest pause time, so that qemu may be upda= ted > to a new version in between. >=20 > cprsave stops the VM and saves vmstate to an ordinary file. It supports = two > modes: restart and reboot. For restart, cprsave exec's the qemu binary (= or > /usr/bin/qemu-exec if it exists) with the same argv. qemu restarts in a > paused state and waits for the cprload command. I think cprsave/cprload could be generalized by using QMP to stash the file descriptors. The 'getfd' QMP command already exists and QEMU code already opens fds passed using this mechanism. I haven't checked but it may be possible to drop some patches by reusing QEMU's monitor file descriptor passing since the code already knows how to open from 'getfd' fds. The reason why using QMP is interesting is because it eliminates the need for execve(2). QEMU may be unable to execute a program due to chroot, seccomp, etc. QMP would enable cprsave/cprload to work both with and without execve(2). One tricky thing with this approach might be startup ordering: how to get fds via the QMP monitor in the new process before processing the entire command-line. Stefan --FF8oNhgXYx8kkWYd Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmCcBZIACgkQnKSrs4Gr c8jYEwf/RBGnLt9skKOND2VsaWoKPVv4sSj8SdRpe4n9O5Cv5Rcy5wy7hmAZejOn PSw6XW9guwfCYbYwED+H6x+XV9TZ68/27awcQ+XGtiCOuV2it97Q9SXecFr18whz j8XmxkRVq4VuY4SSf6s9lk8Pzahh+wQtExV3C0kY7Qommm93Dn/Ynk0Nvu/tUD0O gQEkDJzV1WRB+Vp/iSnYhdt8NUBickbQcB1LDYiDSLYpOG2Cb3xw1Ec6oPqS/FUE oYax8ovgQ9BoLiywY73yYrLi5VbNO39laZYxPpRADOGLs7UcJGzkTGUIURfhyylM 93d16OMcuknXvuA/Dq0PXkHPuW+hTg== =AB/s -----END PGP SIGNATURE----- --FF8oNhgXYx8kkWYd--