virtio: fix 1.0 virtqueue migration

1.0 does not requires physically-contiguous pages layout for a
virtqueue. So we could not infer avail and used from desc. This means
we need to migrate vring.avail and vring.used when host support virtio
1.0. This fixes malfunction of virtio 1.0 device after migration.

Cc: Michael S. Tsirkin <[email protected]>
Cc: Cornelia Huck <[email protected]>
Cc: Dr. David Alan Gilbert <[email protected]>
Signed-off-by: Jason Wang <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>

Author: jasowang

hw/virtio/virtio.c

@@ -1049,6 +1049,61 @@ static bool virtio_64bit_features_needed(void *opaque)
     return (vdev->host_features >> 32) != 0;
 }
 
+static bool virtio_virtqueue_needed(void *opaque)
+{
+    VirtIODevice *vdev = opaque;
+
+    return virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1);
+}
+
+static void put_virtqueue_state(QEMUFile *f, void *pv, size_t size)
+{
+    VirtIODevice *vdev = pv;
+    int i;
+
+    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
+        qemu_put_be64(f, vdev->vq[i].vring.avail);
+        qemu_put_be64(f, vdev->vq[i].vring.used);
+    }
+}
+
+static int get_virtqueue_state(QEMUFile *f, void *pv, size_t size)
+{
+    VirtIODevice *vdev = pv;
+    int i;
+
+    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
+        vdev->vq[i].vring.avail = qemu_get_be64(f);
+        vdev->vq[i].vring.used = qemu_get_be64(f);
+    }
+    return 0;
+}
+
+static VMStateInfo vmstate_info_virtqueue = {
+    .name = "virtqueue_state",
+    .get = get_virtqueue_state,
+    .put = put_virtqueue_state,
+};
+
+static const VMStateDescription vmstate_virtio_virtqueues = {
+    .name = "virtio/virtqueues",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = &virtio_virtqueue_needed,
+    .fields = (VMStateField[]) {
+        {
+            .name         = "virtqueues",
+            .version_id   = 0,
+            .field_exists = NULL,
+            .size         = 0,
+            .info         = &vmstate_info_virtqueue,
+            .flags        = VMS_SINGLE,
+            .offset       = 0,
+        },
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_virtio_device_endian = {
     .name = "virtio/device_endian",
     .version_id = 1,
@@ -1082,6 +1137,7 @@ static const VMStateDescription vmstate_virtio = {
     .subsections = (const VMStateDescription*[]) {
         &vmstate_virtio_device_endian,
         &vmstate_virtio_64bit_features,
+        &vmstate_virtio_virtqueues,
         NULL
     }
 };

include/hw/virtio/virtio.h

@@ -272,6 +272,12 @@ static inline bool virtio_has_feature(VirtIODevice *vdev, unsigned int fbit)
     return __virtio_has_feature(vdev->guest_features, fbit);
 }
 
+static inline bool virtio_host_has_feature(VirtIODevice *vdev,
+                                           unsigned int fbit)
+{
+    return __virtio_has_feature(vdev->host_features, fbit);
+}
+
 static inline bool virtio_is_big_endian(VirtIODevice *vdev)
 {
     if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {