The vm will trigger a disk sweep operation after plugging
a controller who's io type is iothread. If attach a scsi
disk immediately, the sg_inqury request in vm will trigger
the assert in virtio_scsi_ctx_check(), which is called by
virtio_scsi_handle_cmd_req_prepare().
Add judgment in virtio_scsi_handle_cmd_req_prepare() and
return IO Error directly if the device has not been
initialized.
Signed-off-by: Jinhua Cao <caojinhua1@huawei.com>
