[dpdk-dev] [PATCH 2/2] vhost: add thread unsafe async registration functions

[Jiayu Hu]

This patch is to add thread unsafe version for async register and
unregister functions.

Signed-off-by: Jiayu Hu <jiayu.hu at intel.com>
---
 doc/guides/prog_guide/vhost_lib.rst |  12 +++
 lib/vhost/rte_vhost_async.h         |  42 ++++++++++
 lib/vhost/version.map               |   4 +
 lib/vhost/vhost.c                   | 161 +++++++++++++++++++++++++++---------
 4 files changed, 178 insertions(+), 41 deletions(-)

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index d18fb98..6b2745f 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -253,6 +253,12 @@ The following is an overview of some key Vhost API functions:
     vhost invokes this function to get the copy data completed by async
     devices.
 
+* ``rte_vhost_async_channel_register_thread_unsafe(vid, queue_id, features, ops)``
+  Register a vhost queue with async copy device channel without
+  performing any locking.
+
+  This function is only safe to call from within vhost callback functions.
+
 * ``rte_vhost_async_channel_unregister(vid, queue_id)``
 
   Unregister the async copy device channel from a vhost queue.
@@ -265,6 +271,12 @@ The following is an overview of some key Vhost API functions:
   devices for all vhost queues in destroy_device(), when a
   virtio device is paused or shut down.
 
+* ``rte_vhost_async_channel_unregister_thread_unsafe(vid, queue_id)``
+  Unregister the async copy device channel from a vhost queue without
+  performing any locking.
+
+  This function is only safe to call from within vhost callback functions.
+
 * ``rte_vhost_submit_enqueue_burst(vid, queue_id, pkts, count, comp_pkts, comp_count)``
 
   Submit an enqueue request to transmit ``count`` packets from host to guest
diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
index 6faa31f..d054b5f 100644
--- a/lib/vhost/rte_vhost_async.h
+++ b/lib/vhost/rte_vhost_async.h
@@ -143,6 +143,48 @@ __rte_experimental
 int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id);
 
 /**
+ * register an async channel for vhost without performing any locking
+ *
+ * @note This function does not perform any locking, and is only safe to call
+ *       from within vhost callback functions.
+ *
+ * @param vid
+ *  vhost device id async channel to be attached to
+ * @param queue_id
+ *  vhost queue id async channel to be attached to
+ * @param features
+ *  DMA channel feature bit
+ *    b0       : DMA supports inorder data transfer
+ *    b1  - b15: reserved
+ *    b16 - b27: Packet length threshold for DMA transfer
+ *    b28 - b31: reserved
+ * @param ops
+ *  DMA operation callbacks
+ * @return
+ *  0 on success, -1 on failures
+ */
+__rte_experimental
+int rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id,
+	uint32_t features, struct rte_vhost_async_channel_ops *ops);
+
+/**
+ * unregister a dma channel for vhost without performing any lock
+ *
+ * @note This function does not perform any locking, and is only safe to call
+ *       from within vhost callback functions.
+ *
+ * @param vid
+ *  vhost device id DMA channel to be detached
+ * @param queue_id
+ *  vhost queue id DMA channel to be detached
+ * @return
+ *  0 on success, -1 on failures
+ */
+__rte_experimental
+int rte_vhost_async_channel_unregister_thread_unsafe(int vid,
+		uint16_t queue_id);
+
+/**
  * This function submits enqueue data to async engine. Successfully
  * enqueued packets can be transfer completed or being occupied by DMA
  * engines, when this API returns. Transfer completed packets are returned
diff --git a/lib/vhost/version.map b/lib/vhost/version.map
index 9103a23..2363db8 100644
--- a/lib/vhost/version.map
+++ b/lib/vhost/version.map
@@ -79,4 +79,8 @@ EXPERIMENTAL {
 
 	# added in 21.05
 	rte_vhost_get_negotiated_protocol_features;
+
+	# added in 21.08
+	rte_vhost_async_channel_register_thread_unsafe;
+	rte_vhost_async_channel_unregister_thread_unsafe;
 };
diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index c96f633..025e150 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1609,46 +1609,20 @@ int rte_vhost_extern_callback_register(int vid,
 	return 0;
 }
 
-int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
-					uint32_t features,
-					struct rte_vhost_async_channel_ops *ops)
+static __rte_always_inline int
+async_channel_register(int vid, uint16_t queue_id,
+		struct rte_vhost_async_features f,
+		struct rte_vhost_async_channel_ops *ops)
 {
-	struct vhost_virtqueue *vq;
 	struct virtio_net *dev = get_device(vid);
-	struct rte_vhost_async_features f;
+	struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
 	int node;
 
-	if (dev == NULL || ops == NULL)
-		return -1;
-
-	f.intval = features;
-
-	if (queue_id >= VHOST_MAX_VRING)
-		return -1;
-
-	vq = dev->virtqueue[queue_id];
-
-	if (unlikely(vq == NULL || !dev->async_copy))
-		return -1;
-
-	if (unlikely(!f.async_inorder)) {
-		VHOST_LOG_CONFIG(ERR,
-			"async copy is not supported on non-inorder mode "
-			"(vid %d, qid: %d)\n", vid, queue_id);
-		return -1;
-	}
-
-	if (unlikely(ops->check_completed_copies == NULL ||
-		ops->transfer_data == NULL))
-		return -1;
-
-	rte_spinlock_lock(&vq->access_lock);
-
 	if (unlikely(vq->async_registered)) {
 		VHOST_LOG_CONFIG(ERR,
 			"async register failed: channel already registered "
 			"(vid %d, qid: %d)\n", vid, queue_id);
-		goto reg_out;
+		return -1;
 	}
 
 #ifdef RTE_LIBRTE_VHOST_NUMA
@@ -1670,7 +1644,7 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 		VHOST_LOG_CONFIG(ERR,
 			"async register failed: cannot allocate memory for async_pkts_info "
 			"(vid %d, qid: %d)\n", vid, queue_id);
-		goto reg_out;
+		return -1;
 	}
 
 	vq->it_pool = rte_malloc_socket(NULL,
@@ -1681,7 +1655,7 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 		VHOST_LOG_CONFIG(ERR,
 			"async register failed: cannot allocate memory for it_pool "
 			"(vid %d, qid: %d)\n", vid, queue_id);
-		goto reg_out;
+		return -1;
 	}
 
 	vq->vec_pool = rte_malloc_socket(NULL,
@@ -1692,7 +1666,7 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 		VHOST_LOG_CONFIG(ERR,
 			"async register failed: cannot allocate memory for vec_pool "
 			"(vid %d, qid: %d)\n", vid, queue_id);
-		goto reg_out;
+		return -1;
 	}
 
 	if (vq_is_packed(dev)) {
@@ -1704,7 +1678,7 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 			VHOST_LOG_CONFIG(ERR,
 				"async register failed: cannot allocate memory for async buffers "
 				"(vid %d, qid: %d)\n", vid, queue_id);
-			goto reg_out;
+			return -1;
 		}
 	} else {
 		vq->async_descs_split = rte_malloc_socket(NULL,
@@ -1715,22 +1689,92 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 			VHOST_LOG_CONFIG(ERR,
 				"async register failed: cannot allocate memory for async descs "
 				"(vid %d, qid: %d)\n", vid, queue_id);
-			goto reg_out;
+			return -1;
 		}
 	}
 
 	vq->async_ops.check_completed_copies = ops->check_completed_copies;
 	vq->async_ops.transfer_data = ops->transfer_data;
-
 	vq->async_inorder = f.async_inorder;
 	vq->async_threshold = f.async_threshold;
-
 	vq->async_registered = true;
 
-reg_out:
+	return 0;
+}
+
+int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
+					uint32_t features,
+					struct rte_vhost_async_channel_ops *ops)
+{
+	struct vhost_virtqueue *vq;
+	struct virtio_net *dev = get_device(vid);
+	struct rte_vhost_async_features f;
+	int ret;
+
+	if (dev == NULL || ops == NULL)
+		return -1;
+
+	f.intval = features;
+
+	if (queue_id >= VHOST_MAX_VRING)
+		return -1;
+
+	vq = dev->virtqueue[queue_id];
+
+	if (unlikely(vq == NULL || !dev->async_copy))
+		return -1;
+
+	if (unlikely(!f.async_inorder)) {
+		VHOST_LOG_CONFIG(ERR,
+			"async copy is not supported on non-inorder mode "
+			"(vid %d, qid: %d)\n", vid, queue_id);
+		return -1;
+	}
+
+	if (unlikely(ops->check_completed_copies == NULL ||
+		ops->transfer_data == NULL))
+		return -1;
+
+	rte_spinlock_lock(&vq->access_lock);
+	ret = async_channel_register(vid, queue_id, f, ops);
 	rte_spinlock_unlock(&vq->access_lock);
 
-	return 0;
+	return ret;
+}
+
+int rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id,
+					uint32_t features,
+					struct rte_vhost_async_channel_ops *ops)
+{
+	struct vhost_virtqueue *vq;
+	struct virtio_net *dev = get_device(vid);
+	struct rte_vhost_async_features f;
+
+	if (dev == NULL || ops == NULL)
+		return -1;
+
+	f.intval = features;
+
+	if (queue_id >= VHOST_MAX_VRING)
+		return -1;
+
+	vq = dev->virtqueue[queue_id];
+
+	if (unlikely(vq == NULL || !dev->async_copy))
+		return -1;
+
+	if (unlikely(!f.async_inorder)) {
+		VHOST_LOG_CONFIG(ERR,
+			"async copy is not supported on non-inorder mode "
+			"(vid %d, qid: %d)\n", vid, queue_id);
+		return -1;
+	}
+
+	if (unlikely(ops->check_completed_copies == NULL ||
+		ops->transfer_data == NULL))
+		return -1;
+
+	return async_channel_register(vid, queue_id, f, ops);
 }
 
 int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
@@ -1780,5 +1824,40 @@ int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
 	return ret;
 }
 
+int rte_vhost_async_channel_unregister_thread_unsafe(int vid,
+		uint16_t queue_id)
+{
+	struct vhost_virtqueue *vq;
+	struct virtio_net *dev = get_device(vid);
+
+	if (dev == NULL)
+		return -1;
+
+	if (queue_id >= VHOST_MAX_VRING)
+		return -1;
+
+	vq = dev->virtqueue[queue_id];
+
+	if (vq == NULL)
+		return -1;
+
+	if (!vq->async_registered)
+		return 0;
+
+	if (vq->async_pkts_inflight_n) {
+		VHOST_LOG_CONFIG(ERR, "Failed to unregister async channel. "
+			"async inflight packets must be completed before unregistration.\n");
+		return -1;
+	}
+
+	vhost_free_async_mem(vq);
+
+	vq->async_ops.transfer_data = NULL;
+	vq->async_ops.check_completed_copies = NULL;
+	vq->async_registered = false;
+
+	return 0;
+}
+
 RTE_LOG_REGISTER_SUFFIX(vhost_config_log_level, config, INFO);
 RTE_LOG_REGISTER_SUFFIX(vhost_data_log_level, data, WARNING);
-- 
2.7.4