Fix virtio migration

I misunderstood the vmstate macro definition when I reworked the
virtio .get/.put.
The VMSTATE_STRUCT_VARRAY_KNOWN, was described as being for "a
variable length array (i.e. _type *_field) but we know the
length".  However it actually specified operation for arrays embedded in
the struct (i.e. _type _field[]) since it lacked the VMS_POINTER
flag. This caused offset calculation to be completely off, examining and
potentially sending random data instead of the VirtQueue content.

Replace the otherwise unused VMSTATE_STRUCT_VARRAY_KNOWN with a
VMSTATE_STRUCT_VARRAY_POINTER_KNOWN that includes the VMS_POINTER flag
(so now actually doing what it advertises) and use it in the virtio
migration code.

Fixes and description as per Sascha's suggestions/debug.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reported-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Tested-By: Sascha Silbe <silbe@linux.vnet.ibm.com>
Reviewed-By: Sascha Silbe <silbe@linux.vnet.ibm.com>

Fixes: 50e5ae4dc3e4f21e874512f9e87b93b5472d26e0
Fixes: 2cf0148674430b6693c60d42b7eef721bfa9509f
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 63a7b6d..0603793 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1143,8 +1143,8 @@ static const VMStateDescription vmstate_virtio_virtqueues = {
     .minimum_version_id = 1,
     .needed = &virtio_virtqueue_needed,
     .fields = (VMStateField[]) {
-        VMSTATE_STRUCT_VARRAY_KNOWN(vq, struct VirtIODevice, VIRTIO_QUEUE_MAX,
-                      0, vmstate_virtqueue, VirtQueue),
+        VMSTATE_STRUCT_VARRAY_POINTER_KNOWN(vq, struct VirtIODevice,
+                      VIRTIO_QUEUE_MAX, 0, vmstate_virtqueue, VirtQueue),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -1165,8 +1165,8 @@ static const VMStateDescription vmstate_virtio_ringsize = {
     .minimum_version_id = 1,
     .needed = &virtio_ringsize_needed,
     .fields = (VMStateField[]) {
-        VMSTATE_STRUCT_VARRAY_KNOWN(vq, struct VirtIODevice, VIRTIO_QUEUE_MAX,
-                      0, vmstate_ringsize, VirtQueue),
+        VMSTATE_STRUCT_VARRAY_POINTER_KNOWN(vq, struct VirtIODevice,
+                      VIRTIO_QUEUE_MAX, 0, vmstate_ringsize, VirtQueue),
         VMSTATE_END_OF_LIST()
     }
 };