[PATCH v5 10/10] hw/audio/virtio-sound: add missing vmstate fields

[Alexander Mikhalitsyn <alexander@mihalicyn.com>]

From: Volker Rümelin <vr_qemu@t-online.de>

The virtio-sound device is currently not migratable. Add the
missing VMSTATE fields, enable migration and reconnect the audio
streams after migration.

The queue_inuse[] array variables mimic the inuse variable in
struct VirtQueue which is private. They are needed to restart
the virtio queues after migration.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
[AM: trivial rebase changes]
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
v4:
	- added assert(. > 0) before decremeting s->queue_inuse[.]
	  (suggested by Manos Pitsidianakis)
v3:
	- added latency_bytes field to VMStateDescription

	As suggested by Marc-André Lureau:
	- removed the "rc" variable from virtio_snd_post_load()
	- dropped info field from VMStateDescription, because
	  it can't be modified by guest and initialized only from realize
	- added minimum_version_id/version_id so we can extend VMStateDescription
	  without breaking compatibility in the future
---
 hw/audio/virtio-snd.c         | 83 +++++++++++++++++++++++++++++++----
 include/hw/audio/virtio-snd.h |  1 +
 2 files changed, 76 insertions(+), 8 deletions(-)

diff --git a/hw/audio/virtio-snd.c b/hw/audio/virtio-snd.c
index 12473862d24..6df7ea0eb04 100644
--- a/hw/audio/virtio-snd.c
+++ b/hw/audio/virtio-snd.c
@@ -24,7 +24,6 @@
 #include "qapi/error.h"
 #include "hw/audio/virtio-snd.h"
 
-#define VIRTIO_SOUND_VM_VERSION 1
 #define VIRTIO_SOUND_JACK_DEFAULT 0
 #define VIRTIO_SOUND_STREAM_DEFAULT 2
 #define VIRTIO_SOUND_CHMAP_DEFAULT 0
@@ -74,17 +73,40 @@ static uint32_t supported_rates = BIT(VIRTIO_SND_PCM_RATE_5512)
                                 | BIT(VIRTIO_SND_PCM_RATE_192000)
                                 | BIT(VIRTIO_SND_PCM_RATE_384000);
 
+static const VMStateDescription vmstate_virtio_snd_stream = {
+    .name = "virtio-sound-stream",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT32(state, VirtIOSoundPCMStream),
+        VMSTATE_UINT32(params.buffer_bytes, VirtIOSoundPCMStream),
+        VMSTATE_UINT32(params.period_bytes, VirtIOSoundPCMStream),
+        VMSTATE_UINT32(params.features, VirtIOSoundPCMStream),
+        VMSTATE_UINT8(params.channels, VirtIOSoundPCMStream),
+        VMSTATE_UINT8(params.format, VirtIOSoundPCMStream),
+        VMSTATE_UINT8(params.rate, VirtIOSoundPCMStream),
+        VMSTATE_UINT32(latency_bytes, VirtIOSoundPCMStream),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 static const VMStateDescription vmstate_virtio_snd_device = {
-    .name = TYPE_VIRTIO_SND,
-    .version_id = VIRTIO_SOUND_VM_VERSION,
-    .minimum_version_id = VIRTIO_SOUND_VM_VERSION,
+    .name = "virtio-sound-device",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT32_ARRAY(queue_inuse, VirtIOSound, VIRTIO_SND_VQ_MAX),
+        VMSTATE_STRUCT_VARRAY_POINTER_UINT32(streams, VirtIOSound,
+            snd_conf.streams,
+            vmstate_virtio_snd_stream, VirtIOSoundPCMStream),
+        VMSTATE_END_OF_LIST()
+    },
 };
 
 static const VMStateDescription vmstate_virtio_snd = {
-    .name = TYPE_VIRTIO_SND,
-    .unmigratable = 1,
-    .minimum_version_id = VIRTIO_SOUND_VM_VERSION,
-    .version_id = VIRTIO_SOUND_VM_VERSION,
+    .name = "virtio-sound",
+    .version_id = 1,
+    .minimum_version_id = 1,
     .fields = (const VMStateField[]) {
         VMSTATE_VIRTIO_DEVICE,
         VMSTATE_END_OF_LIST()
@@ -813,6 +835,8 @@ process_cmd(VirtIOSound *s, virtio_snd_ctrl_command *cmd)
                  sizeof(virtio_snd_hdr));
     virtqueue_push(cmd->vq, cmd->elem,
                    sizeof(virtio_snd_hdr) + cmd->payload_size);
+    g_assert(s->queue_inuse[VIRTIO_SND_VQ_CONTROL] > 0);
+    s->queue_inuse[VIRTIO_SND_VQ_CONTROL] -= 1;
     virtio_notify(VIRTIO_DEVICE(s), cmd->vq);
 }
 
@@ -859,6 +883,7 @@ static void virtio_snd_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 
     elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
     while (elem) {
+        s->queue_inuse[VIRTIO_SND_VQ_CONTROL] += 1;
         cmd = g_new0(virtio_snd_ctrl_command, 1);
         cmd->elem = elem;
         cmd->vq = vq;
@@ -976,6 +1001,7 @@ static void virtio_snd_handle_tx_xfer(VirtIODevice *vdev, VirtQueue *vq)
             goto tx_err;
         }
 
+        vsnd->queue_inuse[VIRTIO_SND_VQ_TX] += 1;
         buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer) + size);
         buffer->elem = elem;
         buffer->populated = false;
@@ -1060,6 +1086,7 @@ static void virtio_snd_handle_rx_xfer(VirtIODevice *vdev, VirtQueue *vq)
             goto rx_err;
         }
 
+        vsnd->queue_inuse[VIRTIO_SND_VQ_RX] += 1;
         buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer) + size);
         buffer->elem = elem;
         buffer->vq = vq;
@@ -1200,6 +1227,8 @@ static inline void return_tx_buffer(VirtIOSoundPCMStream *stream,
     virtqueue_push(buffer->vq,
                    buffer->elem,
                    sizeof(virtio_snd_pcm_status));
+    g_assert(stream->s->queue_inuse[VIRTIO_SND_VQ_TX] > 0);
+    stream->s->queue_inuse[VIRTIO_SND_VQ_TX] -= 1;
     virtio_notify(VIRTIO_DEVICE(stream->s), buffer->vq);
     QSIMPLEQ_REMOVE(&stream->queue,
                     buffer,
@@ -1293,6 +1322,8 @@ static inline void return_rx_buffer(VirtIOSoundPCMStream *stream,
     virtqueue_push(buffer->vq,
                    buffer->elem,
                    sizeof(virtio_snd_pcm_status) + buffer->size);
+    g_assert(stream->s->queue_inuse[VIRTIO_SND_VQ_RX] > 0);
+    stream->s->queue_inuse[VIRTIO_SND_VQ_RX] -= 1;
     virtio_notify(VIRTIO_DEVICE(stream->s), buffer->vq);
     QSIMPLEQ_REMOVE(&stream->queue,
                     buffer,
@@ -1411,6 +1442,37 @@ static void virtio_snd_unrealize(DeviceState *dev)
     virtio_cleanup(vdev);
 }
 
+static int virtio_snd_post_load(VirtIODevice *vdev)
+{
+    VirtIOSound *s = VIRTIO_SND(vdev);
+    uint32_t i;
+
+    for (i = 0; i < s->snd_conf.streams; i++) {
+        struct VirtIOSoundPCMStream *stream;
+
+        stream = virtio_snd_pcm_get_stream(s, i);
+        if (virtio_snd_pcm_state_prepared(stream->state)) {
+            virtio_snd_pcm_open(stream);
+
+            if (stream->state == VIRTIO_SND_PCM_STATE_STARTED) {
+                virtio_snd_pcm_set_active(stream, true);
+            }
+        }
+    }
+
+    for (i = 0; i < VIRTIO_SND_VQ_MAX; i++) {
+        if (s->queue_inuse[i]) {
+            if (!virtqueue_rewind(s->queues[i], s->queue_inuse[i])) {
+                error_report(
+                    "virtio-snd: could not rewind %u elements in queue %u",
+                    s->queue_inuse[i], i);
+            }
+            s->queue_inuse[i] = 0;
+        }
+    }
+
+    return 0;
+}
 
 static void virtio_snd_reset(VirtIODevice *vdev)
 {
@@ -1442,6 +1504,10 @@ static void virtio_snd_reset(VirtIODevice *vdev)
             virtio_snd_pcm_buffer_free(buffer);
         }
     }
+
+    for (uint32_t i = 0; i < VIRTIO_SND_VQ_MAX; i++) {
+        vsnd->queue_inuse[i] = 0;
+    }
 }
 
 static void virtio_snd_class_init(ObjectClass *klass, const void *data)
@@ -1455,6 +1521,7 @@ static void virtio_snd_class_init(ObjectClass *klass, const void *data)
 
     dc->vmsd = &vmstate_virtio_snd;
     vdc->vmsd = &vmstate_virtio_snd_device;
+    vdc->post_load = virtio_snd_post_load;
     vdc->realize = virtio_snd_realize;
     vdc->unrealize = virtio_snd_unrealize;
     vdc->get_config = virtio_snd_get_config;
diff --git a/include/hw/audio/virtio-snd.h b/include/hw/audio/virtio-snd.h
index 85d5d7c8619..384d2868c19 100644
--- a/include/hw/audio/virtio-snd.h
+++ b/include/hw/audio/virtio-snd.h
@@ -194,6 +194,7 @@ struct VirtIOSound {
     VirtIODevice parent_obj;
 
     VirtQueue *queues[VIRTIO_SND_VQ_MAX];
+    uint32_t queue_inuse[VIRTIO_SND_VQ_MAX];
     uint64_t features;
     VirtIOSoundPCMStream *streams;
     AudioBackend *audio_be;
-- 
2.47.3