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=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 0E82FC43446 for ; Tue, 14 Jul 2020 21:02:06 +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 CA1562064C for ; Tue, 14 Jul 2020 21:02:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HVrNrLxb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA1562064C 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]:49846 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jvS3x-0006iW-35 for qemu-devel@archiver.kernel.org; Tue, 14 Jul 2020 17:02:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51198) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jvS2M-0005jL-QG for qemu-devel@nongnu.org; Tue, 14 Jul 2020 17:00:27 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:27433 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jvS2J-0004e3-6h for qemu-devel@nongnu.org; Tue, 14 Jul 2020 17:00:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594760421; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cSM5fxb0uVcO9SHCvJ1b0FiIX2VVoi8pq0fYNwpoFkw=; b=HVrNrLxbLswJwFhfp3/lfBw8E6Qf9MMWuB9okMw5m88QBratG9EajfAMye0aAwxNKvVGoQ oTB6MynKn4I0JZTncLLc0cYtE8cmciKDb2EvWD52y6kNf4B8MpuR/PbVO9PrhEhrZcBzor M8sbxbPPzEAwl/K8rewbdLu3eRyD5XM= 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-435-CagJpU0GMwKjZGZf3TfEbQ-1; Tue, 14 Jul 2020 17:00:18 -0400 X-MC-Unique: CagJpU0GMwKjZGZf3TfEbQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7B450A4D15; Tue, 14 Jul 2020 21:00:12 +0000 (UTC) Received: from x1.home (ovpn-112-71.phx2.redhat.com [10.3.112.71]) by smtp.corp.redhat.com (Postfix) with ESMTP id C8DB610013C3; Tue, 14 Jul 2020 20:59:48 +0000 (UTC) Date: Tue, 14 Jul 2020 14:59:48 -0600 From: Alex Williamson To: "Dr. David Alan Gilbert" Subject: Re: device compatibility interface for live migration with assigned devices Message-ID: <20200714145948.17b95eb3@x1.home> In-Reply-To: <20200714171946.GL2728@work-vm> References: <20200713232957.GD5955@joy-OptiPlex-7040> <20200714102129.GD25187@redhat.com> <20200714101616.5d3a9e75@x1.home> <20200714171946.GL2728@work-vm> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Received-SPF: pass client-ip=207.211.31.81; envelope-from=alex.williamson@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/14 12:02:09 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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: kvm@vger.kernel.org, libvir-list@redhat.com, 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, Yan Zhao , eskultet@redhat.com, jian-feng.ding@intel.com, zhenyuw@linux.intel.com, hejie.xu@intel.com, bao.yumeng@zte.com.cn, smooney@redhat.com, intel-gvt-dev@lists.freedesktop.org, "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" , cohuck@redhat.com, dinechin@redhat.com, devel@ovirt.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 14 Jul 2020 18:19:46 +0100 "Dr. David Alan Gilbert" wrote: > * Alex Williamson (alex.williamson@redhat.com) wrote: > > On Tue, 14 Jul 2020 11:21:29 +0100 > > Daniel P. Berrang=C3=A9 wrote: > > =20 > > > On Tue, Jul 14, 2020 at 07:29:57AM +0800, Yan Zhao wrote: =20 > > > > hi folks, > > > > we are defining a device migration compatibility interface that hel= ps upper > > > > layer stack like openstack/ovirt/libvirt to check if two devices are > > > > live migration compatible. > > > > The "devices" here could be MDEVs, physical devices, or hybrid of t= he two. > > > > e.g. we could use it to check whether > > > > - a src MDEV can migrate to a target MDEV, > > > > - a src VF in SRIOV can migrate to a target VF in SRIOV, > > > > - a src MDEV can migration to a target VF in SRIOV. > > > > (e.g. SIOV/SRIOV backward compatibility case) > > > >=20 > > > > The upper layer stack could use this interface as the last step to = check > > > > if one device is able to migrate to another device before triggerin= g a real > > > > live migration procedure. > > > > we are not sure if this interface is of value or help to you. pleas= e don't > > > > hesitate to drop your valuable comments. > > > >=20 > > > >=20 > > > > (1) interface definition > > > > The interface is defined in below way: > > > >=20 > > > > __ userspace > > > > /\ \ > > > > / \write > > > > / read \ > > > > ________/__________ ___\|/_____________ > > > > | migration_version | | migration_version |-->check migration > > > > --------------------- --------------------- compatibility > > > > device A device B > > > >=20 > > > >=20 > > > > a device attribute named migration_version is defined under each de= vice's > > > > sysfs node. e.g. (/sys/bus/pci/devices/0000\:00\:02.0/$mdev_UUID/mi= gration_version). > > > > userspace tools read the migration_version as a string from the sou= rce device, > > > > and write it to the migration_version sysfs attribute in the target= device. > > > >=20 > > > > The userspace should treat ANY of below conditions as two devices n= ot compatible: > > > > - any one of the two devices does not have a migration_version attr= ibute > > > > - error when reading from migration_version attribute of one device > > > > - error when writing migration_version string of one device to > > > > migration_version attribute of the other device > > > >=20 > > > > The string read from migration_version attribute is defined by devi= ce vendor > > > > driver and is completely opaque to the userspace. > > > > for a Intel vGPU, string format can be defined like > > > > "parent device PCI ID" + "version of gvt driver" + "mdev type" + "a= ggregator count". > > > >=20 > > > > for an NVMe VF connecting to a remote storage. it could be > > > > "PCI ID" + "driver version" + "configured remote storage URL" > > > >=20 > > > > for a QAT VF, it may be > > > > "PCI ID" + "driver version" + "supported encryption set". > > > >=20 > > > > (to avoid namespace confliction from each vendor, we may prefix a d= river name to > > > > each migration_version string. e.g. i915-v1-8086-591d-i915-GVTg_V5_= 8-1) =20 > >=20 > > It's very strange to define it as opaque and then proceed to describe > > the contents of that opaque string. The point is that its contents > > are defined by the vendor driver to describe the device, driver version, > > and possibly metadata about the configuration of the device. One > > instance of a device might generate a different string from another. > > The string that a device produces is not necessarily the only string > > the vendor driver will accept, for example the driver might support > > backwards compatible migrations. =20 >=20 > (As I've said in the previous discussion, off one of the patch series) >=20 > My view is it makes sense to have a half-way house on the opaqueness of > this string; I'd expect to have an ID and version that are human > readable, maybe a device ID/name that's human interpretable and then a > bunch of other cruft that maybe device/vendor/version specific. >=20 > I'm thinking that we want to be able to report problems and include the > string and the user to be able to easily identify the device that was > complaining and notice a difference in versions, and perhaps also use > it in compatibility patterns to find compatible hosts; but that does > get tricky when it's a 'ask the device if it's compatible'. In the reply I just sent to Dan, I gave this example of what a "compatibility string" might look like represented as json: { "device_api": "vfio-pci", "vendor": "vendor-driver-name", "version": { "major": 0, "minor": 1 }, "vfio-pci": { // Based on above device_api "vendor": 0x1234, // Values for the exposed device "device": 0x5678, // Possibly further parameters for a more specific match }, "mdev_attrs": [ { "attribute0": "VALUE" } ] } Are you thinking that we might allow the vendor to include a vendor specific array where we'd simply require that both sides have matching fields and values? ie. "vendor_fields": [ { "unknown_field0": "unknown_value0" }, { "unknown_field1": "unknown_value1" }, ] We could certainly make that part of the spec, but I can't really figure the value of it other than to severely restrict compatibility, which the vendor could already do via the version.major value. Maybe they'd want to put a build timestamp, random uuid, or source sha1 into such a field to make absolutely certain compatibility is only determined between identical builds? Thanks, Alex