+static inline int
+desc_is_avail(struct vring_packed_desc *desc, bool wrap_counter)
+{
+ uint16_t flags = __atomic_load_n(&desc->flags, __ATOMIC_ACQUIRE);
+
+ return wrap_counter == !!(flags & VRING_PACKED_DESC_F_AVAIL) &&
+ wrap_counter != !!(flags & VRING_PACKED_DESC_F_USED);
+}
+
+static uint32_t
+virtio_user_handle_ctrl_msg_packed(struct virtio_user_dev *dev,
+ struct vring_packed *vring,
+ uint16_t idx_hdr)
+{
+ struct virtio_net_ctrl_hdr *hdr;
+ virtio_net_ctrl_ack status = ~0;
+ uint16_t idx_data, idx_status;
+ /* initialize to one, header is first */
+ uint32_t n_descs = 1;
+
+ /* locate desc for header, data, and status */
+ idx_data = idx_hdr + 1;
+ if (idx_data >= dev->queue_size)
+ idx_data -= dev->queue_size;
+
+ n_descs++;
+
+ idx_status = idx_data;
+ while (vring->desc[idx_status].flags & VRING_DESC_F_NEXT) {
+ idx_status++;
+ if (idx_status >= dev->queue_size)
+ idx_status -= dev->queue_size;
+ n_descs++;
+ }
+
+ hdr = (void *)(uintptr_t)vring->desc[idx_hdr].addr;
+ if (hdr->class == VIRTIO_NET_CTRL_MQ &&
+ hdr->cmd == VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET) {
+ uint16_t queues;
+
+ queues = *(uint16_t *)(uintptr_t)
+ vring->desc[idx_data].addr;
+ status = virtio_user_handle_mq(dev, queues);
+ } else if (hdr->class == VIRTIO_NET_CTRL_RX ||
+ hdr->class == VIRTIO_NET_CTRL_MAC ||
+ hdr->class == VIRTIO_NET_CTRL_VLAN) {
+ status = 0;
+ }
+
+ /* Update status */
+ *(virtio_net_ctrl_ack *)(uintptr_t)
+ vring->desc[idx_status].addr = status;
+
+ /* Update used descriptor */
+ vring->desc[idx_hdr].id = vring->desc[idx_status].id;
+ vring->desc[idx_hdr].len = sizeof(status);
+
+ return n_descs;
+}
+
+void
+virtio_user_handle_cq_packed(struct virtio_user_dev *dev, uint16_t queue_idx)
+{
+ struct virtio_user_queue *vq = &dev->packed_queues[queue_idx];
+ struct vring_packed *vring = &dev->packed_vrings[queue_idx];
+ uint16_t n_descs, flags;
+
+ /* Perform a load-acquire barrier in desc_is_avail to
+ * enforce the ordering between desc flags and desc
+ * content.
+ */
+ while (desc_is_avail(&vring->desc[vq->used_idx],
+ vq->used_wrap_counter)) {
+
+ n_descs = virtio_user_handle_ctrl_msg_packed(dev, vring,
+ vq->used_idx);
+
+ flags = VRING_DESC_F_WRITE;
+ if (vq->used_wrap_counter)
+ flags |= VRING_PACKED_DESC_F_AVAIL_USED;
+
+ __atomic_store_n(&vring->desc[vq->used_idx].flags, flags,
+ __ATOMIC_RELEASE);
+
+ vq->used_idx += n_descs;
+ if (vq->used_idx >= dev->queue_size) {
+ vq->used_idx -= dev->queue_size;
+ vq->used_wrap_counter ^= 1;
+ }
+ }
+}
+