On Tue, 21 May 2019 09:21:57 +0200 Jens Freimann <jfreim...@redhat.com> 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. FWIW, I'd probably stop at Ethernet class devices, vfio doesn't really expose whether a device is a VF, so we'd likely need to resort to getting that info through sysfs. It also seems like there might be some limited-use cases of copying the MAC from a PF to the virtio nic or use of utilities on the host for modifiying a PF MAC, perhaps via eeprom. So while we expect the typical use case to be a VF, it's probably ugly and unnecessarily restrictive to enforce it. Thanks, Alex
