[PATCH v6 13/26] virtio: queue_reset: struct virtio_config_ops add callbacks for queue_reset

[Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>]

Performing reset on a queue is divided into four steps:

 1. reset_vq()                     - notify the device to reset the queue
 2. virtqueue_detach_unused_buf()  - recycle the buffer submitted
 3. virtqueue_reset_vring()        - reset the vring (may re-alloc)
 4. enable_reset_vq()              - mmap vring to device, and enable the queue

So add two callbacks reset_vq, enable_reset_vq to struct
virtio_config_ops.

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 include/linux/virtio_config.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 4d107ad31149..d51906b1389f 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -74,6 +74,15 @@ struct virtio_shm_region {
  * @set_vq_affinity: set the affinity for a virtqueue (optional).
  * @get_vq_affinity: get the affinity for a virtqueue (optional).
  * @get_shm_region: get a shared memory region based on the index.
+ * @reset_vq: reset a queue individually (optional).
+ *	vq: the virtqueue
+ *	Returns 0 on success or error status
+ *	Caller should guarantee that the vring is not accessed by any functions
+ *	of virtqueue.
+ * @enable_reset_vq: enable a reset queue
+ *	vq: the virtqueue
+ *	Returns 0 on success or error status
+ *	If reset_vq is set, then enable_reset_vq must also be set.
  */
 typedef void vq_callback_t(struct virtqueue *);
 struct virtio_config_ops {
@@ -100,6 +109,8 @@ struct virtio_config_ops {
 			int index);
 	bool (*get_shm_region)(struct virtio_device *vdev,
 			       struct virtio_shm_region *region, u8 id);
+	int (*reset_vq)(struct virtqueue *vq);
+	int (*enable_reset_vq)(struct virtqueue *vq);
 };
 
 /* If driver didn't advertise the feature, it will never appear. */
-- 
2.31.0