virtio-scsi: Forbid devices with different iothreads sharing a blockdev

This patch forbids attaching a disk to a SCSI device if its using a
different AioContext. Test case included.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/scsi/virtio-scsi.c

@@ -791,9 +791,16 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     SCSIDevice *sd = SCSI_DEVICE(dev);
 
     if (s->ctx && !s->dataplane_fenced) {
+        AioContext *ctx;
         if (blk_op_is_blocked(sd->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
             return;
         }
+        ctx = blk_get_aio_context(sd->conf.blk);
+        if (ctx != s->ctx && ctx != qemu_get_aio_context()) {
+            error_setg(errp, "Cannot attach a blockdev that is using "
+                       "a different iothread");
+            return;
+        }
         virtio_scsi_acquire(s);
         blk_set_aio_context(sd->conf.blk, s->ctx);
         virtio_scsi_release(s);

tests/qemu-iotests/240

@@ -101,6 +101,28 @@ run_qemu <<EOF
 { "execute": "quit"}
 EOF
 
+echo
+echo === Attach two SCSI disks using the same block device but different iothreads ===
+echo
+
+run_qemu <<EOF
+{ "execute": "qmp_capabilities" }
+{ "execute": "blockdev-add", "arguments": {"driver": "null-co", "node-name": "hd0", "read-only": true}}
+{ "execute": "object-add", "arguments": {"qom-type": "iothread", "id": "iothread0"}}
+{ "execute": "object-add", "arguments": {"qom-type": "iothread", "id": "iothread1"}}
+{ "execute": "device_add", "arguments": {"id": "scsi0", "driver": "${virtio_scsi}", "iothread": "iothread0"}}
+{ "execute": "device_add", "arguments": {"id": "scsi1", "driver": "${virtio_scsi}", "iothread": "iothread1"}}
+{ "execute": "device_add", "arguments": {"id": "scsi-hd0", "driver": "scsi-hd", "drive": "hd0", "bus": "scsi0.0"}}
+{ "execute": "device_add", "arguments": {"id": "scsi-hd1", "driver": "scsi-hd", "drive": "hd0", "bus": "scsi1.0"}}
+{ "execute": "device_del", "arguments": {"id": "scsi-hd0"}}
+{ "execute": "device_add", "arguments": {"id": "scsi-hd1", "driver": "scsi-hd", "drive": "hd0", "bus": "scsi1.0"}}
+{ "execute": "device_del", "arguments": {"id": "scsi-hd1"}}
+{ "execute": "device_del", "arguments": {"id": "scsi0"}}
+{ "execute": "device_del", "arguments": {"id": "scsi1"}}
+{ "execute": "blockdev-del", "arguments": {"node-name": "hd0"}}
+{ "execute": "quit"}
+EOF
+
 # success, all done
 echo "*** done"
 rm -f $seq.full

tests/qemu-iotests/240.out

@@ -31,4 +31,24 @@ QMP_VERSION
 {"return": {}}
 {"return": {}}
 {"return": {}}
+
+=== Attach two SCSI disks using the same block device but different iothreads ===
+
+Testing:
+QMP_VERSION
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"error": {"class": "GenericError", "desc": "Cannot attach a blockdev that is using a different iothread"}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
 *** done