vhost: add APIs to get inflight ring

This patch introduces two APIs. one is for getting inflgiht
ring and the other is for getting base.

Signed-off-by: Lin Li <lilin24@baidu.com>
Signed-off-by: Xun Ni <nixun@baidu.com>
Signed-off-by: Yu Zhang <zhangyu31@baidu.com>
Signed-off-by: Jin Yu <jin.yu@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

lib/librte_vhost/rte_vhost.h

@@ -709,6 +709,23 @@ int rte_vhost_get_mem_table(int vid, struct rte_vhost_memory **mem);
 int rte_vhost_get_vhost_vring(int vid, uint16_t vring_idx,
 			      struct rte_vhost_vring *vring);
 
+/**
+ * Get guest inflight vring info, including inflight ring and resubmit list.
+ *
+ * @param vid
+ *  vhost device ID
+ * @param vring_idx
+ *  vring index
+ * @param vring
+ *  the structure to hold the requested inflight vring info
+ * @return
+ *  0 on success, -1 on failure
+ */
+__rte_experimental
+int
+rte_vhost_get_vhost_ring_inflight(int vid, uint16_t vring_idx,
+	struct rte_vhost_ring_inflight *vring);
+
 /**
  * Set split inflight descriptor.
  *
@@ -885,6 +902,29 @@ int
 rte_vhost_get_vring_base(int vid, uint16_t queue_id,
 		uint16_t *last_avail_idx, uint16_t *last_used_idx);
 
+/**
+ * Get last_avail/last_used of the vhost virtqueue
+ *
+ * This function is designed for the reconnection and it's specific for
+ * the packed ring as we can get the two parameters from the inflight
+ * queueregion
+ *
+ * @param vid
+ *  vhost device ID
+ * @param queue_id
+ *  vhost queue index
+ * @param last_avail_idx
+ *  vhost last_avail_idx to get
+ * @param last_used_idx
+ *  vhost last_used_idx to get
+ * @return
+ *  0 on success, -1 on failure
+ */
+__rte_experimental
+int
+rte_vhost_get_vring_base_from_inflight(int vid,
+	uint16_t queue_id, uint16_t *last_avail_idx, uint16_t *last_used_idx);
+
 /**
  * Set last_avail/used_idx of the vhost virtqueue
  *

lib/librte_vhost/rte_vhost_version.map

@@ -93,4 +93,6 @@ EXPERIMENTAL {
 	rte_vhost_set_last_inflight_io_packed;
 	rte_vhost_clr_inflight_desc_split;
 	rte_vhost_clr_inflight_desc_packed;
+	rte_vhost_get_vhost_ring_inflight;
+	rte_vhost_get_vring_base_from_inflight;
 };

lib/librte_vhost/vhost.c

@@ -823,6 +823,41 @@ rte_vhost_get_vhost_vring(int vid, uint16_t vring_idx,
 	return 0;
 }
 
+int
+rte_vhost_get_vhost_ring_inflight(int vid, uint16_t vring_idx,
+				  struct rte_vhost_ring_inflight *vring)
+{
+	struct virtio_net *dev;
+	struct vhost_virtqueue *vq;
+
+	dev = get_device(vid);
+	if (unlikely(!dev))
+		return -1;
+
+	if (vring_idx >= VHOST_MAX_VRING)
+		return -1;
+
+	vq = dev->virtqueue[vring_idx];
+	if (unlikely(!vq))
+		return -1;
+
+	if (vq_is_packed(dev)) {
+		if (unlikely(!vq->inflight_packed))
+			return -1;
+
+		vring->inflight_packed = vq->inflight_packed;
+	} else {
+		if (unlikely(!vq->inflight_split))
+			return -1;
+
+		vring->inflight_split = vq->inflight_split;
+	}
+
+	vring->resubmit_inflight = vq->resubmit_inflight;
+
+	return 0;
+}
+
 int
 rte_vhost_set_inflight_desc_split(int vid, uint16_t vring_idx,
 				  uint16_t idx)
@@ -1318,6 +1353,32 @@ int rte_vhost_get_vring_base(int vid, uint16_t queue_id,
 	return 0;
 }
 
+int
+rte_vhost_get_vring_base_from_inflight(int vid,
+				       uint16_t queue_id,
+				       uint16_t *last_avail_idx,
+				       uint16_t *last_used_idx)
+{
+	struct rte_vhost_inflight_info_packed *inflight_info;
+	struct virtio_net *dev = get_device(vid);
+
+	if (dev == NULL || last_avail_idx == NULL || last_used_idx == NULL)
+		return -1;
+
+	if (!vq_is_packed(dev))
+		return -1;
+
+	inflight_info = dev->virtqueue[queue_id]->inflight_packed;
+	if (!inflight_info)
+		return -1;
+
+	*last_avail_idx = (inflight_info->old_used_wrap_counter << 15) |
+			  inflight_info->old_used_idx;
+	*last_used_idx = *last_avail_idx;
+
+	return 0;
+}
+
 int rte_vhost_set_vring_base(int vid, uint16_t queue_id,
 		uint16_t last_avail_idx, uint16_t last_used_idx)
 {