[PATCH v4 21/26] vhost: add support for virtqueue state get event

[Maxime Coquelin <maxime.coquelin@redhat.com>]

This patch adds support for VDUSE_GET_VQ_STATE event
handling, which consists in providing the backend last
available index for the specified virtqueue.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
---
 lib/vhost/vduse.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/vhost/vduse.c b/lib/vhost/vduse.c
index 92c515cff2..7e36c50b6c 100644
--- a/lib/vhost/vduse.c
+++ b/lib/vhost/vduse.c
@@ -147,6 +147,7 @@ vduse_events_handler(int fd, void *arg, int *remove __rte_unused)
 	struct virtio_net *dev = arg;
 	struct vduse_dev_request req;
 	struct vduse_dev_response resp;
+	struct vhost_virtqueue *vq;
 	int ret;
 
 	memset(&resp, 0, sizeof(resp));
@@ -165,6 +166,13 @@ vduse_events_handler(int fd, void *arg, int *remove __rte_unused)
 			vduse_req_id_to_str(req.type), req.type);
 
 	switch (req.type) {
+	case VDUSE_GET_VQ_STATE:
+		vq = dev->virtqueue[req.vq_state.index];
+		VHOST_LOG_CONFIG(dev->ifname, INFO, "\tvq index: %u, avail_index: %u\n",
+				req.vq_state.index, vq->last_avail_idx);
+		resp.vq_state.split.avail_index = vq->last_avail_idx;
+		resp.result = VDUSE_REQ_RESULT_OK;
+		break;
 	default:
 		resp.result = VDUSE_REQ_RESULT_FAILED;
 		break;
-- 
2.40.1