[PATCH v2 4/4] virtio-gpu: fix v2 migration

[marcandre . lureau]

From: Peter Xu <peterx@redhat.com>

Commit dfcf74fa ("virtio-gpu: fix scanout migration post-load") broke
forward/backward version migration. Versioning of nested VMSD structures
is not straightforward, as the wire format doesn't have nested
structures versions. Use the x-vmstate-version introduced before and a
field test to save/load appropriately according to the machine version.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/display/virtio-gpu.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 7f9fb5eacc..5de90bb62f 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -1166,6 +1166,14 @@ static void virtio_gpu_cursor_bh(void *opaque)
     virtio_gpu_handle_cursor(&g->parent_obj.parent_obj, g->cursor_vq);
 }
 
+static bool vmstate_after_v2(void *opaque, int version)
+{
+    struct VirtIOGPUBase *base = container_of(opaque, VirtIOGPUBase, scanout);
+    struct VirtIOGPU *gpu = container_of(base, VirtIOGPU, parent_obj);
+
+    return gpu->vmstate_version >= 2;
+}
+
 static const VMStateDescription vmstate_virtio_gpu_scanout = {
     .name = "virtio-gpu-one-scanout",
     .version_id = 2,
@@ -1181,12 +1189,12 @@ static const VMStateDescription 
vmstate_virtio_gpu_scanout = {
         VMSTATE_UINT32(cursor.hot_y, struct virtio_gpu_scanout),
         VMSTATE_UINT32(cursor.pos.x, struct virtio_gpu_scanout),
         VMSTATE_UINT32(cursor.pos.y, struct virtio_gpu_scanout),
-        VMSTATE_UINT32_V(fb.format, struct virtio_gpu_scanout, 2),
-        VMSTATE_UINT32_V(fb.bytes_pp, struct virtio_gpu_scanout, 2),
-        VMSTATE_UINT32_V(fb.width, struct virtio_gpu_scanout, 2),
-        VMSTATE_UINT32_V(fb.height, struct virtio_gpu_scanout, 2),
-        VMSTATE_UINT32_V(fb.stride, struct virtio_gpu_scanout, 2),
-        VMSTATE_UINT32_V(fb.offset, struct virtio_gpu_scanout, 2),
+        VMSTATE_UINT32_TEST(fb.format, struct virtio_gpu_scanout, 
vmstate_after_v2),
+        VMSTATE_UINT32_TEST(fb.bytes_pp, struct virtio_gpu_scanout, 
vmstate_after_v2),
+        VMSTATE_UINT32_TEST(fb.width, struct virtio_gpu_scanout, 
vmstate_after_v2),
+        VMSTATE_UINT32_TEST(fb.height, struct virtio_gpu_scanout, 
vmstate_after_v2),
+        VMSTATE_UINT32_TEST(fb.stride, struct virtio_gpu_scanout, 
vmstate_after_v2),
+        VMSTATE_UINT32_TEST(fb.offset, struct virtio_gpu_scanout, 
vmstate_after_v2),
         VMSTATE_END_OF_LIST()
     },
 };
@@ -1660,7 +1668,7 @@ static Property virtio_gpu_properties[] = {
     DEFINE_PROP_BIT("blob", VirtIOGPU, parent_obj.conf.flags,
                     VIRTIO_GPU_FLAG_BLOB_ENABLED, false),
     DEFINE_PROP_SIZE("hostmem", VirtIOGPU, parent_obj.conf.hostmem, 0),
-    DEFINE_PROP_UINT8("x-vmstate-version", VirtIOGPU, vmstate_version, 1),
+    DEFINE_PROP_UINT8("x-vmstate-version", VirtIOGPU, vmstate_version, 2),
     DEFINE_PROP_END_OF_LIST(),
 };
 
-- 
2.41.0.28.gd7d8841f67