virtio: provide a method to get the IRQ affinity mask for a virtqueue

This basically passed up the pci_irq_get_affinity information through
virtio through an optional get_vq_affinity method.  It is only implemented
by the PCI backend for now, and only when we use per-virtqueue IRQs.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jason Wang <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
5 files changed