Commit 3e996cc5 authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Michael S. Tsirkin
Browse files

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: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Reported-by: default avatarSascha Silbe <silbe@linux.vnet.ibm.com>
Tested-By: default avatarSascha Silbe <silbe@linux.vnet.ibm.com>
Reviewed-By: default avatarSascha Silbe <silbe@linux.vnet.ibm.com>

Fixes: 50e5ae4d
Fixes: 2cf01486
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Tested-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
parent 382d34ff

hw/virtio/virtio.c

+4 −4
Original line number Diff line number Diff line
@@ -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()

    }

};

include/migration/vmstate.h

+9 −9
Original line number Diff line number Diff line
@@ -386,26 +386,26 @@ extern const VMStateInfo vmstate_info_bitmap; 
    .offset       = vmstate_offset_array(_state, _field, _type, _num),\

}



/* a variable length array (i.e. _type *_field) but we know the

 * length

 */

#define VMSTATE_STRUCT_VARRAY_KNOWN(_field, _state, _num, _version, _vmsd, _type) { \

#define VMSTATE_STRUCT_VARRAY_UINT8(_field, _state, _field_num, _version, _vmsd, _type) { \

    .name       = (stringify(_field)),                               \

    .num          = (_num),                                          \

    .num_offset = vmstate_offset_value(_state, _field_num, uint8_t), \

    .version_id = (_version),                                        \

    .vmsd       = &(_vmsd),                                          \

    .size       = sizeof(_type),                                     \

    .flags      = VMS_STRUCT|VMS_ARRAY,                              \

    .flags      = VMS_STRUCT|VMS_VARRAY_UINT8,                       \

    .offset     = offsetof(_state, _field),                          \

}



#define VMSTATE_STRUCT_VARRAY_UINT8(_field, _state, _field_num, _version, _vmsd, _type) { \

/* a variable length array (i.e. _type *_field) but we know the

 * length

 */

#define VMSTATE_STRUCT_VARRAY_POINTER_KNOWN(_field, _state, _num, _version, _vmsd, _type) { \

    .name       = (stringify(_field)),                               \

    .num_offset = vmstate_offset_value(_state, _field_num, uint8_t), \

    .num          = (_num),                                          \

    .version_id = (_version),                                        \

    .vmsd       = &(_vmsd),                                          \

    .size       = sizeof(_type),                                     \

    .flags      = VMS_STRUCT|VMS_VARRAY_UINT8,                       \

    .flags      = VMS_STRUCT|VMS_ARRAY|VMS_POINTER,                  \

    .offset     = offsetof(_state, _field),                          \

}