Re: [libvirt PATCH v2 1/6] qemu: add capabilities flag for failover feature

Presence of the virtio-net-pci option called "failover" indicates support in a qemu binary of a simplistic bonding of a virtio-net device with another PCI device. This feature allows migration of guests that have a network device assigned to a guest with VFIO, by creating a network bond device in the guest consisting of the VFIO-assigned device and a virtio-net-pci device, then temporarily (and automatically) unplugging the VFIO net device prior to migration (and hotplugging an equivalent device on the migration destination). (The feature is called "failover" because the bond device uses the vfio-pci netdev for normal guest networking, but "fails over" to the virtio-net-pci netdev once the vfio-pci device is unplugged for migration.) Full functioning of the feature also requires support in the virtio-net driver in the guest OS (since that is where the bond device resides), but if the "failover" commandline option is present for the virtio-net-pci device in qemu, at least the qemu part of the feature is available, and libvirt can add the proper options to both the virtio-net-pci and vfio-pci device commandlines to indicate qemu should attempt doing the failover during migration. This patch just adds the qemu capabilities flag "virtio-net.failover". Signed-off-by: Laine Stump <laine(a)redhat.com&gt; --- No change from V1. src/qemu/qemu_capabilities.c | 4 ++++ src/qemu/qemu_capabilities.h | 3 +++ tests/qemucapabilitiesdata/caps_4.2.0.aarch64.xml | 1 + tests/qemucapabilitiesdata/caps_4.2.0.x86_64.xml | 1 + 4 files changed, 9 insertions(+)