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 <jfreim...@redhat.com> 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
