[v1,1/2] vhost: introduce DMA vchannel unconfiguration

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index bad4d819e1..78b1943d29 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -323,6 +323,11 @@  The following is an overview of some key Vhost API functions:
   Get device type of vDPA device, such as VDPA_DEVICE_TYPE_NET,
   VDPA_DEVICE_TYPE_BLK.
 
+* ``rte_vhost_async_dma_unconfigure(dma_id, vchan_id)``
+
+  Clear DMA vChannels finished to use. This function needs to
+  be called after async unregister.
+
 Vhost-user Implementations
 --------------------------
 
diff --git a/doc/guides/rel_notes/release_22_11.rst b/doc/guides/rel_notes/release_22_11.rst
index 8c021cf050..e94c006e39 100644
--- a/doc/guides/rel_notes/release_22_11.rst
+++ b/doc/guides/rel_notes/release_22_11.rst
@@ -55,6 +55,8 @@  New Features
      Also, make sure to start the actual text at the margin.
      =======================================================
 
+* **Added vhost API to unconfigure DMA vchannels.**
+  Added an API which helps to unconfigure DMA vchannels.
 
 Removed Items
 -------------
diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
index 1db2a10124..0442e027fd 100644
--- a/lib/vhost/rte_vhost_async.h
+++ b/lib/vhost/rte_vhost_async.h
@@ -266,6 +266,23 @@  rte_vhost_async_try_dequeue_burst(int vid, uint16_t queue_id,
 	struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count,
 	int *nr_inflight, int16_t dma_id, uint16_t vchan_id);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice.
+ *
+ * Unconfigure DMA vChannels in asynchronous data path.
+ *
+ * @param dma_id
+ *  the identifier of DMA device
+ * @param vchan_id
+ *  the identifier of virtual DMA channel
+ * @return
+ *  0 on success, and -1 on failure
+ */
+__rte_experimental
+int
+rte_vhost_async_dma_unconfigure(int16_t dma_id, uint16_t vchan_id);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/vhost/version.map b/lib/vhost/version.map
index 18574346d5..013a6bcc42 100644
--- a/lib/vhost/version.map
+++ b/lib/vhost/version.map
@@ -96,6 +96,9 @@  EXPERIMENTAL {
 	rte_vhost_async_try_dequeue_burst;
 	rte_vhost_driver_get_vdpa_dev_type;
 	rte_vhost_clear_queue;
+
+	# added in 22.11
+	rte_vhost_async_dma_unconfigure;
 };
 
 INTERNAL {
diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 60cb05a0ff..d215c917a2 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1863,6 +1863,43 @@  rte_vhost_async_channel_unregister_thread_unsafe(int vid, uint16_t queue_id)
 	return 0;
 }
 
+int
+rte_vhost_async_dma_unconfigure(int16_t dma_id, uint16_t vchan_id)
+{
+	struct rte_dma_info info;
+	void *pkts_cmpl_flag_addr;
+
+	if (!rte_dma_is_valid(dma_id)) {
+		VHOST_LOG_CONFIG("dma", ERR, "DMA %d is not found.\n", dma_id);
+		return -1;
+	}
+
+	if (rte_dma_info_get(dma_id, &info) != 0) {
+		VHOST_LOG_CONFIG("dma", ERR, "Fail to get DMA %d information.\n", dma_id);
+		return -1;
+	}
+
+	if (vchan_id >= info.max_vchans) {
+		VHOST_LOG_CONFIG("dma", ERR, "Invalid DMA %d vChannel %u.\n", dma_id, vchan_id);
+		return -1;
+	}
+
+	pkts_cmpl_flag_addr = dma_copy_track[dma_id].vchans[vchan_id].pkts_cmpl_flag_addr;
+	if (pkts_cmpl_flag_addr) {
+		rte_free(pkts_cmpl_flag_addr);
+		pkts_cmpl_flag_addr = NULL;
+	}
+
+	if (dma_copy_track[dma_id].vchans) {
+		rte_free(dma_copy_track[dma_id].vchans);
+		dma_copy_track[dma_id].vchans = NULL;
+	}
+
+	dma_copy_track[dma_id].nr_vchans--;
+
+	return 0;
+}
+
 int
 rte_vhost_async_dma_configure(int16_t dma_id, uint16_t vchan_id)
 {