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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 3E404C433E0 for ; Mon, 27 Jul 2020 07:35:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 06E992072E for ; Mon, 27 Jul 2020 07:35:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726998AbgG0Hfq (ORCPT ); Mon, 27 Jul 2020 03:35:46 -0400 Received: from mga04.intel.com ([192.55.52.120]:50149 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726270AbgG0Hfp (ORCPT ); Mon, 27 Jul 2020 03:35:45 -0400 IronPort-SDR: i+RsR8zaNm7rLl4VjwSk1N3Fj8rgVj/H2zXOHsHzebfcFg7A160xlHQn2kodmdlhJ6l7yUw+oI 1No9h3Ux6vUA== X-IronPort-AV: E=McAfee;i="6000,8403,9694"; a="148444271" X-IronPort-AV: E=Sophos;i="5.75,401,1589266800"; d="scan'208";a="148444271" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jul 2020 00:35:45 -0700 IronPort-SDR: 0ffjI+i+TsbheWV9B1ekyPjpDXDKX5V9QqFeMTIOUgqFnBjB7356oNacj5t1wADBNDmVTD6CU1 TSX+YyW3cBSQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,401,1589266800"; d="scan'208";a="364039470" Received: from joy-optiplex-7040.sh.intel.com (HELO joy-OptiPlex-7040) ([10.239.13.16]) by orsmga001.jf.intel.com with ESMTP; 27 Jul 2020 00:35:38 -0700 Date: Mon, 27 Jul 2020 15:24:40 +0800 From: Yan Zhao To: Alex Williamson Cc: kvm@vger.kernel.org, libvir-list@redhat.com, Jason Wang , qemu-devel@nongnu.org, kwankhede@nvidia.com, eauger@redhat.com, xin-ran.wang@intel.com, corbet@lwn.net, openstack-discuss@lists.openstack.org, shaohe.feng@intel.com, kevin.tian@intel.com, eskultet@redhat.com, jian-feng.ding@intel.com, dgilbert@redhat.com, zhenyuw@linux.intel.com, hejie.xu@intel.com, bao.yumeng@zte.com.cn, smooney@redhat.com, intel-gvt-dev@lists.freedesktop.org, berrange@redhat.com, cohuck@redhat.com, dinechin@redhat.com, devel@ovirt.org Subject: Re: device compatibility interface for live migration with assigned devices Message-ID: <20200727072440.GA28676@joy-OptiPlex-7040> Reply-To: Yan Zhao References: <20200713232957.GD5955@joy-OptiPlex-7040> <9bfa8700-91f5-ebb4-3977-6321f0487a63@redhat.com> <20200716083230.GA25316@joy-OptiPlex-7040> <20200717101258.65555978@x1.home> <20200721005113.GA10502@joy-OptiPlex-7040> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200721005113.GA10502@joy-OptiPlex-7040> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org > > As you indicate, the vendor driver is responsible for checking version > > information embedded within the migration stream. Therefore a > > migration should fail early if the devices are incompatible. Is it > but as I know, currently in VFIO migration protocol, we have no way to > get vendor specific compatibility checking string in migration setup stage > (i.e. .save_setup stage) before the device is set to _SAVING state. > In this way, for devices who does not save device data in precopy stage, > the migration compatibility checking is as late as in stop-and-copy > stage, which is too late. > do you think we need to add the getting/checking of vendor specific > compatibility string early in save_setup stage? > hi Alex, after an offline discussion with Kevin, I realized that it may not be a problem if migration compatibility check in vendor driver occurs late in stop-and-copy phase for some devices, because if we report device compatibility attributes clearly in an interface, the chances for libvirt/openstack to make a wrong decision is little. so, do you think we are now arriving at an agreement that we'll give up the read-and-test scheme and start to defining one interface (perhaps in json format), from which libvirt/openstack is able to parse and find out compatibility list of a source mdev/physical device? Thanks Yan