virtio-scsi: handle ctrl virtqueue in main loop

virtio-scsi: handle ctrl virtqueue in main loop

Previously the ctrl virtqueue was handled in the AioContext where SCSI
requests are processed. When IOThread Virtqueue Mapping was added things
become more complicated because SCSI requests could run in other
AioContexts.

Simplify by handling the ctrl virtqueue in the main loop where reset
operations can be performed. Note that BHs are still used canceling SCSI
requests in their AioContexts but at least the mean loop activity
doesn't need BHs anymore.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250311132616.1049687-13-stefanha@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>