info on resize support for virtio disk

[Gianluca Cecchi]

hello,
I'm using F14+virt-preview repo and I have an f15 guest configured
with a virtio disk.

I'm trying online resize  support for guest disk if in place.

So my disk is vda in guest and in guest xml I have:

<disk type='file' device='disk'>
  <driver name='qemu' type='raw'/>
  <source file='/var/lib/libvirt/images/f15_001.img'/>
  <target dev='vda' bus='virtio'/>
  <address type='pci' domain='0x0000' bus='0x00'
slot='0x06' function='0x0'/>
</disk>

I extend the disk with qemu-img at host side:
qemu-img resize /var/lib/libvirt/images/f15_001.img +1G

In guest neither partprobe nor kpartx show any change...
I put the xml definition in disk.xml and try to update device from
libvirt point of view (my domain id is 4):

[root ~]# virsh update-device 4 disk.xml
error: Failed to update device from disk.xml
error: unsupported configuration: disk bus 'virtio' cannot be updated.

Any confirmation of this?
Teorically qemu/monitor should support block_resize command for virtio
devices too in qemu 0.14....
Is this true but functionality not ported to virsh command yet or
other kind of things?
Thanks for clarifications

Gianluca