Add queue select feature

Author: Cuda-Chen

virtio-snd.c

@@ -16,6 +16,13 @@
 
 #define PRIV(x) ((virtio_snd_config_t *) x->priv)
 
+enum {
+    VSND_QUEUE_CTRL = 0,
+    VSND_QUEUE_EVT = 1,
+    VSND_QUEUE_TX = 2,
+    VSND_QUEUE_RX = 3,
+};
+
 /* supported virtio sound version */
 enum {
     VSND_FEATURES_0 = 0,
@@ -707,7 +714,11 @@ static bool virtio_snd_reg_write(virtio_snd_state_t *vsnd,
         return true;
     case _(QueueNotify):
         if (value < ARRAY_SIZE(vsnd->queues)) {
-            virtio_queue_notify_handler(vsnd, value);
+            switch (value) {
+            case VSND_QUEUE_CTRL:
+                virtio_queue_notify_handler(vsnd, value);
+                break;
+            }
         } else {
             virtio_snd_set_fail(vsnd);
         }