[PULL v3 10/32] virtio: don't enable notifications during polling

From: Stefan Hajnoczi Virtqueue notifications are not necessary during polling, so we disable them. This allows the guest driver to avoid MMIO vmexits. Unfortunately the virtio-blk and virtio-scsi handler functions re-enable notifications, defeating this optimization. Fix virtio-blk and virtio-

[PULL v3 10/32] virtio: don't enable notifications during polling

From: Stefan Hajnoczi Virtqueue notifications are not necessary during polling, so we disable them. This allows the guest driver to avoid MMIO vmexits. Unfortunately the virtio-blk and virtio-scsi handler functions re-enable notifications, defeating this optimization. Fix virtio-blk and virtio-