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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 55294C32750 for ; Fri, 2 Aug 2019 15:07:04 +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 28799204EC for ; Fri, 2 Aug 2019 15:07:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 28799204EC 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]:35548 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1htZ95-0006EE-BU for qemu-devel@archiver.kernel.org; Fri, 02 Aug 2019 11:07:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47062) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1htZ8K-0004eO-JF for qemu-devel@nongnu.org; Fri, 02 Aug 2019 11:06:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1htZ8I-0005DZ-OC for qemu-devel@nongnu.org; Fri, 02 Aug 2019 11:06:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13122) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1htZ8I-0005D1-Fs for qemu-devel@nongnu.org; Fri, 02 Aug 2019 11:06:14 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 87BA53090FCE for ; Fri, 2 Aug 2019 15:06:13 +0000 (UTC) Received: from localhost (dhcp-192-195.str.redhat.com [10.33.192.195]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7351B5D713; Fri, 2 Aug 2019 15:06:06 +0000 (UTC) From: Jens Freimann To: qemu-devel@nongnu.org Date: Fri, 2 Aug 2019 17:05:56 +0200 Message-Id: <20190802150605.5880-1-jfreimann@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Fri, 02 Aug 2019 15:06:13 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 0/9] add failover feature for assigned network devices 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: pkrempa@redhat.com, berrange@redhat.com, ehabkost@redhat.com, mst@redhat.com, aadam@redhat.com, laine@redhat.com, ailan@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is implementing the host side of the net_failover concept (https://www.kernel.org/doc/html/latest/networking/net_failover.html) Changes since v1: - add new QMP events, - one is send when the primary device is unplugged - one is send when VIRTIO_NET_F_STANDBY is not negotiated. This is needed because we hide the primary device until the feature bit is negotiated and then add it with qdev_add_device(). The event is for libvirt to be aware of that. - patch 7/9: a new migration state, called wait-unplug. It is entered after SETUP and before ACTIVE. In this phase we check devices for pending guest unplug complete event. This patch still has a problem. It checks in a loop if there are still devices that are not unplugged by the guest. If the guest never returns it will run forever. How to terminate this loop? I thought about a timed wait semaphore or just spinning for a certain amount of t= ime, but nothing seems good. Any ideas here? - patch 2/9: When unplugging the primary devices, only do the guest part = i.e. call hotplug_handler_unplug_request() which calls the pcie attention button code. The unrealize part is not done so the ressources of the device are not freed. In case of migration failure we can re-plug the = device to the guest with hotplug_handler_hotplug(). I tested migration failure an= d a following second attempt to migrate that doesn't fail. - add the primary device on the target VM, done in runstate change handler. - fix error reporting (dgilbert) - get rid of timer to add device after feature negotiation The general idea is that we have a pair of devices, a vfio-pci and a virtio-net device. Before migration the vfio device is unplugged and data flows to the virtio-net device, on the target side another vfio-pci devic= e 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. * Patch 1 adds the infrastructure to hide the device for the qbus and qde= v APIs * Patch 2 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. It also implements the migration handler to unplug the device from the guest an= d re-plug in case of migration failure * Patch 3 and 4 make sure that we can unplug the vfio-device before migration starts * Patch 5 and 6 add new qmp events, one sends the device id of a device that was just requested to be unplugged from the guest and another one to let libvirt know if VIRTIO_NET_F_STANDBY was negotiated * Patch 7 adds a new migration state that is entered while we wait for devices to be unplugged by guest OS * Patch 8 sets a new flag for PCIDevice 'partially_hotplugged' which we use to skip the unrealize code path when doing a unplug of the primary device * Patch 9 sets the pending_deleted_event before triggering the guest unplug request Previous discussion: RFC v1 https://patchwork.ozlabs.org/cover/989098/ RFC v2 https://www.mail-archive.com/qemu-devel@nongnu.org/msg606906.htm= l v1: https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg03968.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 need to let libvirt know what's happening. Add new qmp events and a new migration state. When a primary device is (partially) unplugged (only from guest) we send a qmp event with the device id. = When it is unplugged from the guest the DEVICE_DELETED event is sent. Migration will enter the wait-unplug state while waiting for the gue= st os to unplug all primary devices and then move on with migration. 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. Thi= s is an attempt to keep it simple and contained in QEMU as much as possib= le. One of the problems that stopped management software and libvirt fro= m implementing this idea is that it can't be sure that it's possible t= o re-plug the primary device. By not freeing the devices resources in = QEMU and only asking the guest OS to unplug it is possible to re-plug the device in case of a migration failure. 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=3Dsplit -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=3Droot0,multifunction=3Don,chassis=3D0,= addr=3D0xa \ -device pcie-root-port,id=3Droot1,bus=3Dpcie.0,chassis=3D1 \ -device pcie-root-port,id=3Droot2,bus=3Dpcie.0,chassis=3D2 \ -netdev tap,script=3D/root/bin/bridge.sh,downscript=3Dno,id=3Dhos= tnet1,vhost=3Don \ -device virtio-net-pci,netdev=3Dhostnet1,id=3Dnet1,mac=3D52:54:00= :6f:55:cc,bus=3Droot2,failover=3Don \ -device vfio-pci,host=3D5e:00.2,id=3Dhostdev0,bus=3Droot1,standby=3Dnet1= \ /root/rhel-guest-image-8.0-1781.x86_64.qcow2 I'm grateful for any remarks or ideas! Thanks! Changes from RFCv2 to v1: - work around circular dependency of commandline options. Just add failover=3Don to the virtio-net standby options and reference it from primary (vfio-pci) device with standby=3D - 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. Jens Freimann (9): qdev/qbus: Add hidden device support net/virtio: add failover support vfio: unplug failover primary device before migration migration: allow unplug during migration for failover devices qapi: add unplug primary event qapi: Add failover negotiated event migration: Add new migration state wait-unplug pci: mark devices partially unplugged pci: mark device having guest unplug request pending hw/core/qdev.c | 20 ++++ hw/net/virtio-net.c | 180 +++++++++++++++++++++++++++++++++ hw/pci/pci.c | 2 + hw/pci/pcie.c | 6 ++ hw/vfio/pci.c | 25 ++++- hw/vfio/pci.h | 2 + include/hw/pci/pci.h | 1 + include/hw/qdev-core.h | 9 ++ include/hw/virtio/virtio-net.h | 13 +++ include/hw/virtio/virtio.h | 1 + include/migration/vmstate.h | 2 + migration/migration.c | 14 +++ migration/savevm.c | 18 ++++ migration/savevm.h | 1 + qapi/migration.json | 24 ++++- qapi/net.json | 16 +++ qdev-monitor.c | 43 +++++++- vl.c | 6 +- 18 files changed, 375 insertions(+), 8 deletions(-) --=20 2.21.0