[RFC v2 3/4] vduse: update the vq_info in ioctl

[Cindy Lu <lulu@redhat.com>]

In VDUSE_VQ_GET_INFO, the driver will sync the last_avail_idx
with reconnect info, After mapping the reconnect pages to userspace
The userspace App will update the reconnect_time in
struct vhost_reconnect_vring, If this is not 0 then it means this
vq is reconnected and will update the last_avail_idx

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 13 +++++++++++++
 include/uapi/linux/vduse.h         |  6 ++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 2c69f4004a6e..680b23dbdde2 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -1221,6 +1221,8 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 		struct vduse_vq_info vq_info;
 		struct vduse_virtqueue *vq;
 		u32 index;
+		struct vdpa_reconnect_info *area;
+		struct vhost_reconnect_vring *vq_reconnect;
 
 		ret = -EFAULT;
 		if (copy_from_user(&vq_info, argp, sizeof(vq_info)))
@@ -1252,6 +1254,17 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 
 		vq_info.ready = vq->ready;
 
+		area = &vq->reconnect_info;
+
+		vq_reconnect = (struct vhost_reconnect_vring *)area->vaddr;
+		/*check if the vq is reconnect, if yes then update the last_avail_idx*/
+		if ((vq_reconnect->last_avail_idx !=
+		     vq_info.split.avail_index) &&
+		    (vq_reconnect->reconnect_time != 0)) {
+			vq_info.split.avail_index =
+				vq_reconnect->last_avail_idx;
+		}
+
 		ret = -EFAULT;
 		if (copy_to_user(argp, &vq_info, sizeof(vq_info)))
 			break;
diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
index 11bd48c72c6c..d585425803fd 100644
--- a/include/uapi/linux/vduse.h
+++ b/include/uapi/linux/vduse.h
@@ -350,4 +350,10 @@ struct vduse_dev_response {
 	};
 };
 
+struct vhost_reconnect_vring {
+	__u16 reconnect_time;
+	__u16 last_avail_idx;
+	_Bool avail_wrap_counter;
+};
+
 #endif /* _UAPI_VDUSE_H_ */
-- 
2.34.3