[RFC PATCH for 8.0 08/13] virtio: expose VirtQueueElementOld

["Eugenio Pérez" <eperezma@redhat.com>]

We will convert between VirtQueueElement and VirtQueueElementOld to
migrate the inflight descriptors, so we need virtio-net to see these.

This will not be exported in the final version, but working with
VirtQueueElementOld is way more easier than with VirtQueueElement and
VMState macros.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 include/hw/virtio/virtio.h | 31 +++++++++++++++++++++++++++++++
 hw/virtio/virtio.c         | 27 +++++----------------------
 2 files changed, 36 insertions(+), 22 deletions(-)

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index acfd4df125..b4c5163fb0 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -75,6 +75,37 @@ typedef struct VirtQueueElement
     struct iovec *out_sg;
 } VirtQueueElement;
 
+/*
+ * Reading and writing a structure directly to QEMUFile is *awful*, but
+ * it is what QEMU has always done by mistake.  We can change it sooner
+ * or later by bumping the version number of the affected vm states.
+ * In the meanwhile, since the in-memory layout of VirtQueueElement
+ * has changed, we need to marshal to and from the layout that was
+ * used before the change.
+ */
+typedef struct VirtQueueElementOld {
+    uint32_t index;
+    uint32_t out_num;
+    uint32_t in_num;
+    hwaddr in_addr[VIRTQUEUE_MAX_SIZE];
+    hwaddr out_addr[VIRTQUEUE_MAX_SIZE];
+    /* Unions help to serialize the descriptor using VMStateDescription */
+    union {
+        struct iovec in_sg[VIRTQUEUE_MAX_SIZE];
+        uint64_t in_sg_64[VIRTQUEUE_MAX_SIZE * 2];
+    };
+    union {
+        struct iovec out_sg[VIRTQUEUE_MAX_SIZE];
+        uint64_t out_sg_64[VIRTQUEUE_MAX_SIZE * 2];
+    };
+} VirtQueueElementOld;
+
+void *qemu_get_virtqueue_element_from_old(VirtIODevice *vdev,
+                                          const VirtQueueElementOld *data,
+                                          size_t sz);
+void qemu_put_virtqueue_element_old(const VirtQueueElement *elem,
+                                    VirtQueueElementOld *data);
+
 #define VIRTIO_QUEUE_MAX 1024
 
 #define VIRTIO_NO_VECTOR 0xffff
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index bc3b474065..5ddc49610c 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2280,27 +2280,10 @@ unsigned int virtqueue_drop_all(VirtQueue *vq)
     }
 }
 
-/* Reading and writing a structure directly to QEMUFile is *awful*, but
- * it is what QEMU has always done by mistake.  We can change it sooner
- * or later by bumping the version number of the affected vm states.
- * In the meanwhile, since the in-memory layout of VirtQueueElement
- * has changed, we need to marshal to and from the layout that was
- * used before the change.
- */
-typedef struct VirtQueueElementOld {
-    uint32_t index;
-    uint32_t out_num;
-    uint32_t in_num;
-    hwaddr in_addr[VIRTQUEUE_MAX_SIZE];
-    hwaddr out_addr[VIRTQUEUE_MAX_SIZE];
-    struct iovec in_sg[VIRTQUEUE_MAX_SIZE];
-    struct iovec out_sg[VIRTQUEUE_MAX_SIZE];
-} VirtQueueElementOld;
-
 /* Convert VirtQueueElementOld to VirtQueueElement */
-static void *qemu_get_virtqueue_element_from_old(VirtIODevice *vdev,
-                                               const VirtQueueElementOld *data,
-                                               size_t sz)
+void *qemu_get_virtqueue_element_from_old(VirtIODevice *vdev,
+                                          const VirtQueueElementOld *data,
+                                          size_t sz)
 {
     VirtQueueElement *elem = virtqueue_alloc_element(sz, data->out_num,
                                                      data->in_num);
@@ -2361,8 +2344,8 @@ void *qemu_get_virtqueue_element(VirtIODevice *vdev, QEMUFile *f, size_t sz)
 }
 
 /* Convert VirtQueueElement to VirtQueueElementOld */
-static void qemu_put_virtqueue_element_old(const VirtQueueElement *elem,
-                                           VirtQueueElementOld *data)
+void qemu_put_virtqueue_element_old(const VirtQueueElement *elem,
+                                    VirtQueueElementOld *data)
 {
     memset(data, 0, sizeof(*data));
     data->index = elem->index;
-- 
2.31.1