From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:53594) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hCKln-0008LQ-9z for qemu-devel@nongnu.org; Fri, 05 Apr 2019 05:04:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hCKeU-00037c-VV for qemu-devel@nongnu.org; Fri, 05 Apr 2019 04:56:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41535) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hCKeU-00036E-8f for qemu-devel@nongnu.org; Fri, 05 Apr 2019 04:56:46 -0400 Date: Fri, 5 Apr 2019 09:56:29 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20190405085628.GA2819@work-vm> References: <20190322134447.14831-1-jfreimann@redhat.com> <20190404082933.ke7tvryocpdd2h54@jenstp.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190404082933.ke7tvryocpdd2h54@jenstp.localdomain> Subject: Re: [Qemu-devel] [RFC PATCH 0/2] implement the failover feature for assigned network devices List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jens Freimann , armbru@redhat.com Cc: qemu-devel@nongnu.org, pkrempa@redhat.com, ehabkost@redhat.com, mst@redhat.com, mdroth@linux.vnet.ibm.com, liran.alon@oracle.com, laine@redhat.com, ogerlitz@mellanox.com, ailan@redhat.com * Jens Freimann (jfreimann@redhat.com) wrote: > ping > > FYI: I'm also working on a few related tools to detect driver behaviour when > assigning a MAC to the vf device. Code is at https://github.com/jensfr/netfailover_driver_detect Hi Jens, I've not been following this too uch, but: > regards, > Jens > > On Fri, Mar 22, 2019 at 02:44:45PM +0100, 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) > > > > 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. A "hidden" boolean is added to the device > > state and it is set based on a callback to the standby device which > > registers itself for handling the assessment: "should the primary device > > be hidden?" by cross validating the ids of the devices. > > > > * In the second patch the virtio-net uses the API to hide the vfio > > device and unhides it when the feature is acked. > > > > Previous discussion: https://patchwork.ozlabs.org/cover/989098/ > > > > 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. This sounds 'fun' - bonus cases are things like what happens if the guest gets rebooted somewhere during the process or if it's currently sitting in the bios/grub/etc > > 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). Are they really that precious? Personally it's not something I'd worry about. > > 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. > > > > There are still some open issues: > > > > Migration: I'm looking for something like a pre-migration hook that I > > could use to unplug the vfio-pci device. I tried with a migration > > notifier but it is called to late, i.e. after migration is aborted due > > to vfio-pci marked unmigrateable. I worked around this by setting it > > to migrateable and used a migration notifier on the virtio-net device. Why not just let this happen at the libvirt level; then you do the hotunplug etc before you actually tell qemu anything about starting a migration? > > Commandline: There is a dependency between vfio-pci and virtio-net > > devices. One points to the other via new parameters > > primar= and standby=''. This means > > that the primary device needs to be specified after standby device on > > the qemu command line. Not sure how to solve this. > > > > Error handling: Patches don't cover all possible error scenarios yet. > > > > 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,primary=hostdev0 \ > > -device vfio-pci,host=5e:00.2,id=hostdev0,bus=root1,standby=net1 \ Yes, that's a bit grim; it's circular dependency on the 'hostdev0' and 'net1' id's. cc'ing in Markus. Dave > > /root/rhel-guest-image-8.0-1781.x86_64.qcow2 > > > > I'm grateful for any remarks or ideas! > > > > Thanks! > > > > regards, > > Jens > > > > Sameeh Jubran (2): > > qdev/qbus: Add hidden device support > > net/virtio: add failover support > > > > hw/core/qdev.c | 27 ++++++++++ > > hw/net/virtio-net.c | 95 ++++++++++++++++++++++++++++++++++ > > hw/pci/pci.c | 1 + > > include/hw/pci/pci.h | 2 + > > include/hw/qdev-core.h | 8 +++ > > include/hw/virtio/virtio-net.h | 7 +++ > > qdev-monitor.c | 48 +++++++++++++++-- > > vl.c | 7 ++- > > 8 files changed, 189 insertions(+), 6 deletions(-) > > > > -- > > 2.20.1 > > > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK 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=-7.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,T_HK_NAME_DR,URIBL_BLOCKED, USER_AGENT_MUTT 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 9EBEAC4360F for ; Fri, 5 Apr 2019 09:09:58 +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 5D022217D7 for ; Fri, 5 Apr 2019 09:09:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5D022217D7 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]:38496 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hCKrF-0004hY-Jr for qemu-devel@archiver.kernel.org; Fri, 05 Apr 2019 05:09:57 -0400 Received: from eggs.gnu.org ([209.51.188.92]:53594) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hCKln-0008LQ-9z for qemu-devel@nongnu.org; Fri, 05 Apr 2019 05:04:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hCKeU-00037c-VV for qemu-devel@nongnu.org; Fri, 05 Apr 2019 04:56:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41535) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hCKeU-00036E-8f for qemu-devel@nongnu.org; Fri, 05 Apr 2019 04:56:46 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 20F244E93D; Fri, 5 Apr 2019 08:56:45 +0000 (UTC) Received: from work-vm (ovpn-117-242.ams2.redhat.com [10.36.117.242]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 50ED9614F2; Fri, 5 Apr 2019 08:56:31 +0000 (UTC) Date: Fri, 5 Apr 2019 09:56:29 +0100 From: "Dr. David Alan Gilbert" To: Jens Freimann , armbru@redhat.com Message-ID: <20190405085628.GA2819@work-vm> References: <20190322134447.14831-1-jfreimann@redhat.com> <20190404082933.ke7tvryocpdd2h54@jenstp.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <20190404082933.ke7tvryocpdd2h54@jenstp.localdomain> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 05 Apr 2019 08:56:45 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [RFC PATCH 0/2] implement the 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, ehabkost@redhat.com, mst@redhat.com, mdroth@linux.vnet.ibm.com, qemu-devel@nongnu.org, liran.alon@oracle.com, laine@redhat.com, ogerlitz@mellanox.com, ailan@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190405085629.GROg5uhBQJVcecwjaufDQvV7EUW-qy3TrRoP80kRLGo@z> * Jens Freimann (jfreimann@redhat.com) wrote: > ping > > FYI: I'm also working on a few related tools to detect driver behaviour when > assigning a MAC to the vf device. Code is at https://github.com/jensfr/netfailover_driver_detect Hi Jens, I've not been following this too uch, but: > regards, > Jens > > On Fri, Mar 22, 2019 at 02:44:45PM +0100, 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) > > > > 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. A "hidden" boolean is added to the device > > state and it is set based on a callback to the standby device which > > registers itself for handling the assessment: "should the primary device > > be hidden?" by cross validating the ids of the devices. > > > > * In the second patch the virtio-net uses the API to hide the vfio > > device and unhides it when the feature is acked. > > > > Previous discussion: https://patchwork.ozlabs.org/cover/989098/ > > > > 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. This sounds 'fun' - bonus cases are things like what happens if the guest gets rebooted somewhere during the process or if it's currently sitting in the bios/grub/etc > > 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). Are they really that precious? Personally it's not something I'd worry about. > > 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. > > > > There are still some open issues: > > > > Migration: I'm looking for something like a pre-migration hook that I > > could use to unplug the vfio-pci device. I tried with a migration > > notifier but it is called to late, i.e. after migration is aborted due > > to vfio-pci marked unmigrateable. I worked around this by setting it > > to migrateable and used a migration notifier on the virtio-net device. Why not just let this happen at the libvirt level; then you do the hotunplug etc before you actually tell qemu anything about starting a migration? > > Commandline: There is a dependency between vfio-pci and virtio-net > > devices. One points to the other via new parameters > > primar= and standby=''. This means > > that the primary device needs to be specified after standby device on > > the qemu command line. Not sure how to solve this. > > > > Error handling: Patches don't cover all possible error scenarios yet. > > > > 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,primary=hostdev0 \ > > -device vfio-pci,host=5e:00.2,id=hostdev0,bus=root1,standby=net1 \ Yes, that's a bit grim; it's circular dependency on the 'hostdev0' and 'net1' id's. cc'ing in Markus. Dave > > /root/rhel-guest-image-8.0-1781.x86_64.qcow2 > > > > I'm grateful for any remarks or ideas! > > > > Thanks! > > > > regards, > > Jens > > > > Sameeh Jubran (2): > > qdev/qbus: Add hidden device support > > net/virtio: add failover support > > > > hw/core/qdev.c | 27 ++++++++++ > > hw/net/virtio-net.c | 95 ++++++++++++++++++++++++++++++++++ > > hw/pci/pci.c | 1 + > > include/hw/pci/pci.h | 2 + > > include/hw/qdev-core.h | 8 +++ > > include/hw/virtio/virtio-net.h | 7 +++ > > qdev-monitor.c | 48 +++++++++++++++-- > > vl.c | 7 ++- > > 8 files changed, 189 insertions(+), 6 deletions(-) > > > > -- > > 2.20.1 > > > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK