[PATCH 2/3] virtio: struct VirtQueue introduce reset

[Xuan Zhuo]

 In the current design, we stop the device from operating on the vring
 during per-queue reset by resetting the structure VirtQueue.

 But before the reset operation, when recycling some resources, we should
 stop referencing new vring resources. For example, when recycling
 virtio-net's asynchronous sending resources, virtio-net should be able
 to perceive that the current queue is in the per-queue reset state, and
 stop sending new packets from the tx queue.

 Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 hw/virtio/virtio.c         | 8 ++++++++
 include/hw/virtio/virtio.h | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 03077b2ecf..907d5b8bde 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2030,6 +2030,12 @@ void virtio_queue_reset(VirtIODevice *vdev, uint32_t 
queue_index)
 {
     VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
 
+    /*
+     * Mark this queue is per-queue reset status. The device should release the
+     * references of the vring, and not refer more new vring item.
+     */
+    vdev->vq[queue_index].reset = true;
+
     if (k->queue_reset) {
         k->queue_reset(vdev, queue_index);
     }
@@ -2053,6 +2059,8 @@ void virtio_queue_enable(VirtIODevice *vdev, uint32_t 
queue_index)
     }
     */
 
+    vdev->vq[queue_index].reset = false;
+
     if (k->queue_enable) {
         k->queue_enable(vdev, queue_index);
     }
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 1c0d77c670..b888538d09 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -251,6 +251,9 @@ struct VirtQueue {
     /* Notification enabled? */
     bool notification;
 
+    /* Per-Queue Reset status */
+    bool reset;
+
     uint16_t queue_index;
 
     unsigned int inuse;
-- 
2.32.0.3.g01195cf9f