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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 596DEC04AAF for ; Tue, 21 May 2019 10:13:35 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2248721773 for ; Tue, 21 May 2019 10:13:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2248721773 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 ([127.0.0.1]:50627 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hT1m2-00075B-8N for qemu-devel@archiver.kernel.org; Tue, 21 May 2019 06:13:34 -0400 Received: from eggs.gnu.org ([209.51.188.92]:47584) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hT1j3-0004k0-Lt for qemu-devel@nongnu.org; Tue, 21 May 2019 06:10:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hT1j2-0002yp-4G for qemu-devel@nongnu.org; Tue, 21 May 2019 06:10:29 -0400 Received: from mail-qk1-f196.google.com ([209.85.222.196]:43482) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1hT1j1-0002xq-WF for qemu-devel@nongnu.org; Tue, 21 May 2019 06:10:28 -0400 Received: by mail-qk1-f196.google.com with SMTP id z6so10640741qkl.10 for ; Tue, 21 May 2019 03:10:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=JlTLQqm5Q1So/Z4/KmDfyVgO0zaxsHBwEZLn9UUKVXU=; b=Qnwm8q1E/8r3Z1JzS3hVfqePfSS4VibDYVS5YNSWZ+eiIdsyF54aPWKgYkyy+wbp7d MEV7sxV+PdOBLIvzV/hFz8eVY+W8XCiEZEmgwG22sfWkrYDdKFIG3DV+FLJAZ4L8GADG feMkCZdQDaRu60QHEquSdG3xPijlIZnAW8tbEhRYqSpRn5NojyxN8hsboJGXIY7Zuwoe GxyhNHuuNO/qcaF/A2vk1ve9LRsKXhiPue+Nz6mOfqIjhnOM+q4pAFgSyA6v/KUi7a2y h32bdf8fdguupBtklXxuIEpE0foNwztFjFBUiHkSSqfWTL8rGtQ0XWqyO3pZxxEx63Az 7n9g== X-Gm-Message-State: APjAAAXWUQ7zIL/7wAwlplVhvZNJtteQQPJuFlgP9OeQVs6RakoMSBAw 0v/jmJURxCZczTntcEhaqTKyhw== X-Google-Smtp-Source: APXvYqwXLvZniFQDBAMgWF40cbZ04B3ve+IDqana/BRhCOYpHMOfcTeND1lxKyP8y4cFMPGcAQw4NQ== X-Received: by 2002:a05:620a:13fc:: with SMTP id h28mr39765274qkl.164.1558433427383; Tue, 21 May 2019 03:10:27 -0700 (PDT) Received: from redhat.com (pool-173-76-105-71.bstnma.fios.verizon.net. [173.76.105.71]) by smtp.gmail.com with ESMTPSA id h20sm11558585qtc.16.2019.05.21.03.10.25 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 21 May 2019 03:10:26 -0700 (PDT) Date: Tue, 21 May 2019 06:10:19 -0400 From: "Michael S. Tsirkin" To: Jens Freimann Message-ID: <20190521060725-mutt-send-email-mst@kernel.org> References: <20190517125820.2885-1-jfreimann@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190517125820.2885-1-jfreimann@redhat.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.222.196 Subject: Re: [Qemu-devel] [PATCH 0/4] add failover feature for assigned network devices X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pkrempa@redhat.com, berrange@redhat.com, ehabkost@redhat.com, aadam@redhat.com, qemu-devel@nongnu.org, laine@redhat.com, ailan@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, May 17, 2019 at 02:58:16PM +0200, Jens Freimann wrote: > This is another attempt at implementing the host side of the > net_failover concept > (https://www.kernel.org/doc/html/latest/networking/net_failover.html) > > Changes since last RFC: > - work around circular dependency of commandline options. Just add > failover=on to the virtio-net standby options and reference it from > primary (vfio-pci) device with standby= > - add patch 3/4 to allow migration of vfio-pci device when it is part of a > failover pair, still disallow for all other devices > - add patch 4/4 to allow unplug of device during migrationm, make an > exception for failover primary devices. I'd like feedback on how to > solve this more elegant. I added a boolean to DeviceState, have it > default to false for all devices except for primary devices. > - not tested yet with surprise removal > - I don't expect this to go in as it is, still needs more testing but > I'd like to get feedback on above mentioned changes. > > The general idea is that we have a pair of devices, a vfio-pci and a > emulated device. Before migration the vfio device is unplugged and data > flows to the emulated device, on the target side another vfio-pci device > is plugged in to take over the data-path. In the guest the net_failover > module will pair net devices with the same MAC address. > > * In the first patch the infrastructure for hiding the device is added > for the qbus and qdev APIs. > > * In the second patch the virtio-net uses the API to defer adding the vfio > device until the VIRTIO_NET_F_STANDBY feature is acked. > > Previous discussion: > RFC v1 https://patchwork.ozlabs.org/cover/989098/ > RFC v2 https://www.mail-archive.com/qemu-devel@nongnu.org/msg606906.html > > To summarize concerns/feedback from previous discussion: > 1.- guest OS can reject or worse _delay_ unplug by any amount of time. > Migration might get stuck for unpredictable time with unclear reason. > This approach combines two tricky things, hot/unplug and migration. > -> We can surprise-remove the PCI device and in QEMU we can do all > necessary rollbacks transparent to management software. Will it be > easy, probably not. > 2. PCI devices are a precious ressource. The primary device should never > be added to QEMU if it won't be used by guest instead of hiding it in > QEMU. > -> We only hotplug the device when the standby feature bit was > negotiated. We save the device cmdline options until we need it for > qdev_device_add() > Hiding a device can be a useful concept to model. For example a > pci device in a powered-off slot could be marked as hidden until the slot is > powered on (mst). > 3. Management layer software should handle this. Open Stack already has > components/code to handle unplug/replug VFIO devices and metadata to > provide to the guest for detecting which devices should be paired. > -> An approach that includes all software from firmware to > higher-level management software wasn't tried in the last years. This is > an attempt to keep it simple and contained in QEMU as much as possible. > 4. Hotplugging a device and then making it part of a failover setup is > not possible > -> addressed by extending qdev hotplug functions to check for hidden > attribute, so e.g. device_add can be used to plug a device. > > > I have tested this with a mlx5 NIC and was able to migrate the VM with > above mentioned workarounds for open problems. > > Command line example: > > qemu-system-x86_64 -enable-kvm -m 3072 -smp 3 \ > -machine q35,kernel-irqchip=split -cpu host \ > -k fr \ > -serial stdio \ > -net none \ > -qmp unix:/tmp/qmp.socket,server,nowait \ > -monitor telnet:127.0.0.1:5555,server,nowait \ > -device pcie-root-port,id=root0,multifunction=on,chassis=0,addr=0xa \ > -device pcie-root-port,id=root1,bus=pcie.0,chassis=1 \ > -device pcie-root-port,id=root2,bus=pcie.0,chassis=2 \ > -netdev tap,script=/root/bin/bridge.sh,downscript=no,id=hostnet1,vhost=on \ > -device virtio-net-pci,netdev=hostnet1,id=net1,mac=52:54:00:6f:55:cc,bus=root2,failover=on \ > /root/rhel-guest-image-8.0-1781.x86_64.qcow2 > > Then the primary device can be hotplugged via > (qemu) device_add vfio-pci,host=5e:00.2,id=hostdev0,bus=root1,standby=net1 > > > I'm grateful for any remarks or ideas! > > Thanks! Hi Jens! Overall I like the patches. Thanks! Could you please tell us a bit more about other hardware: does this work more or less universally across vendors? were any other cards tested? Thanks in advance. > > Jens Freimann (4): > migration: allow unplug during migration for failover devices > qdev/qbus: Add hidden device support > net/virtio: add failover support > vfio: unplug failover primary device before migration > > hw/core/qdev.c | 20 ++++++ > hw/net/virtio-net.c | 117 +++++++++++++++++++++++++++++++++ > hw/vfio/pci.c | 25 ++++++- > hw/vfio/pci.h | 2 + > include/hw/qdev-core.h | 10 +++ > include/hw/virtio/virtio-net.h | 12 ++++ > qdev-monitor.c | 43 ++++++++++-- > vl.c | 6 +- > 8 files changed, 228 insertions(+), 7 deletions(-) > > -- > 2.21.0