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[100.0.197.103]) by smtp.gmail.com with ESMTPSA id j33sm572323qtc.10.2019.05.28.19.54.21 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 28 May 2019 19:54:22 -0700 (PDT) Date: Tue, 28 May 2019 22:54:19 -0400 From: "Michael S. Tsirkin" To: si-wei liu Message-ID: <20190528225039-mutt-send-email-mst@kernel.org> References: <20190517125820.2885-1-jfreimann@redhat.com> <20190520165657.2293c5d7@x1.home> <20190521072157.wpb77wlc5mhfcdes@jenstp.localdomain> <20190521073511-mutt-send-email-mst@kernel.org> <20190521184918.n4nnk6ack3ssp6jv@jenstp.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.222.193 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, Alex Williamson , laine@redhat.com, Jens Freimann , ailan@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, May 28, 2019 at 05:14:22PM -0700, si-wei liu wrote: > > > On 5/21/2019 11:49 AM, Jens Freimann wrote: > > On Tue, May 21, 2019 at 07:37:19AM -0400, Michael S. Tsirkin wrote: > > > On Tue, May 21, 2019 at 09:21:57AM +0200, Jens Freimann wrote: > > > > On Mon, May 20, 2019 at 04:56:57PM -0600, Alex Williamson wrote: > > > > > On Fri, 17 May 2019 14:58:16 +0200 > > > > > Jens Freimann wrote: > > > > > > 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 > > > > > > > > > > Is this standby= option only valid for Network/Ethernet class code > > > > > devices? If so, perhaps vfio-pci code should reject the > > > > option on any > > > > > non-ethernet devices. The option is also non-intuitive for > > > > users, only > > > > > through examples like above can we see it relates to the id of the > > > > > secondary device. Could we instead name it something like > > > > > "standby_net_failover_pair_id="? > > > > > > > > It is only for ethernet (VFs), I will add code to reject > > > > non-ethernet VF devices. > > > > I agree the name is not descriptive and the one you suggest > > > > seems good to > > > > me. > > > > > > > > > > Also, this feature requires matching MAC addresses per the > > > > description, > > > > > where is that done? Is it the user's responsibility to set > > > > the MAC on > > > > > the host device prior to the device_add? If so, is this actually not > > > > > only specific to ethernet devices, but ethernet VFs? > > > > > > > > Yes, it's the users responsibility and the MACs are then matched by > > > > the net_failover driver in the guest. It makes sense for > > > > ethernet VFs only, > > > > I'll add a check for that. > > > > > > Actually is there a list of devices for which this has been tested > > > besides mlx5? I think someone said some old intel cards > > > don't support this well, we might need to blacklist these ... > > > > So far I've tested mlx5 and XL710 which both worked, but I'm > > working on testing with more devices. But of course help with testing > > is greatly appreciated. > It won't work on Intel ixgbe and Broadcom bnxt_en, which requires toggling > the state of tap backing the virtio-net in order to release/reprogram MAC > filter. Actually, it's very few NICs that could work with this - even some > works by chance the behavior is undefined. Instead of blacklisting it makes > more sense to whitelist the NIC that supports it - with some new sysfs > attribute claiming the support presumably. > > -Siwei I agree for many cards we won't know how they behave until we try. One can consider this a bug in Linux that cards don't behave in a consistent way. The best thing to do IMHO would be to write a tool that people can run to test the behaviour. > > > > regards, > > Jens