[Virtio-fs] Live migration support for virtio-fs

[Ge, Xiongzi]

Hello Vivek, Dr. Gilbert, and the virtio-fs team,

It seems that virtio-fs does not support live migration. Once a vm is configured with virtio-fs, live migration cannot be performed even it is not mounted on the guest. Is there any progress for this? If the shared directory is from a distributed file system like Ceph, would it be easier than the general case to be implemented? 

Thanks,
Xiongzi