Re: [RFC PATCH net-next v2 2/2] virtio_net: Extend virtio to use VF datapath when available

[Laine Stump <laine@redhat.com>]

On 01/22/2018 04:05 PM, Samudrala, Sridhar wrote:
> 
> I have been testing this feature using a shell script, but i hope
> someone in the libvirt
> community  will extend 'virsh' to handle live migration when this
> feature is supported.

Each virsh command connects to a single instance of libvirtd on one host
(even the virsh migrate command puts the info about the destination host
into the parameters for a command that it sends to libvirtd on the
source host - virsh itself doesn't directly connect to the destination
host), so the idea of doing all three operations:

 1) unplug assigned device from guest on host A
 2) migrate guest to host B
 3) hotplug assigned device to guest on host B

as a single command is out of scope for virsh. Of course management
software that is designed to manage a *cluster* of hosts (e.g. ovirt,
OpenStack) are connected to libvirtd on both the source and destination
host, so it's more reasonable to expect them to support this
functionality with a single command (or button press, or whatever).

The place where libvirt can and should help is in exposing any new flags
(or other related config) that enable the virtio features in libvirt's
domain configuration XML. For that, don't hesitate to send email to
libvir-list@redhat.com, or ask questions in the #virt channel on OFTC.
Cc me on any mail so I'll see it right away.