vhost: rework async configuration structure

This patch reworks the async configuration structure to improve code readability. In addition, add preserved padding fields on the structure for future usage. Signed-off-by: Jiayu Hu <[email protected]> Reviewed-by: Chenbo Xia <[email protected]> Reviewed-by: Maxime Coquelin <[email protected]>
minhuw · Jul 21, 2021 · acbc388 · acbc388
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diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
@@ -218,26 +218,29 @@ The following is an overview of some key Vhost API functions:
 
   Enable or disable zero copy feature of the vhost crypto backend.
 
-* ``rte_vhost_async_channel_register(vid, queue_id, features, ops)``
+* ``rte_vhost_async_channel_register(vid, queue_id, config, ops)``
 
-  Register a vhost queue with async copy device channel after vring
-  is enabled. Following device ``features`` must be specified together
+  Register an async copy device channel for a vhost queue after vring
+  is enabled. Following device ``config`` must be specified together
   with the registration:
 
-  * ``async_inorder``
+  * ``features``
 
-    Async copy device can guarantee the ordering of copy completion
-    sequence. Copies are completed in the same order with that at
-    the submission time.
+    This field is used to specify async copy device features.
 
-    Currently, only ``async_inorder`` capable device is supported by vhost.
+    ``RTE_VHOST_ASYNC_INORDER`` represents the async copy device can
+    guarantee the order of copy completion is the same as the order
+    of copy submission.
+
+    Currently, only ``RTE_VHOST_ASYNC_INORDER`` capable device is
+    supported by vhost.
 
   * ``async_threshold``
 
     The copy length (in bytes) below which CPU copy will be used even if
     applications call async vhost APIs to enqueue/dequeue data.
 
-    Typical value is 512~1024 depending on the async device capability.
+    Typical value is 256~1024 depending on the async device capability.
 
   Applications must provide following ``ops`` callbacks for vhost lib to
   work with the async copy devices:

diff --git a/examples/vhost/main.c b/examples/vhost/main.c
@@ -1468,19 +1468,19 @@ new_device(int vid)
 		vid, vdev->coreid);
 
 	if (async_vhost_driver) {
-		struct rte_vhost_async_features f;
+		struct rte_vhost_async_config config = {0};
 		struct rte_vhost_async_channel_ops channel_ops;
 
 		if (dma_type != NULL && strncmp(dma_type, "ioat", 4) == 0) {
 			channel_ops.transfer_data = ioat_transfer_data_cb;
 			channel_ops.check_completed_copies =
 				ioat_check_completed_copies_cb;
 
-			f.async_inorder = 1;
-			f.async_threshold = 256;
+			config.features = RTE_VHOST_ASYNC_INORDER;
+			config.async_threshold = 256;
 
 			return rte_vhost_async_channel_register(vid, VIRTIO_RXQ,
-				f.intval, &channel_ops);
+				config, &channel_ops);
 		}
 	}
 

diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
@@ -93,49 +93,47 @@ struct async_inflight_info {
 };
 
 /**
- *  dma channel feature bit definition
+ *  async channel features
  */
-struct rte_vhost_async_features {
-	union {
-		uint32_t intval;
-		struct {
-			uint32_t async_inorder:1;
-			uint32_t resvd_0:15;
-			uint32_t async_threshold:12;
-			uint32_t resvd_1:4;
-		};
-	};
+enum {
+	RTE_VHOST_ASYNC_INORDER = 1U << 0,
 };
 
 /**
- * register an async channel for vhost
+ *  async channel configuration
+ */
+struct rte_vhost_async_config {
+	uint32_t async_threshold;
+	uint32_t features;
+	uint32_t rsvd[2];
+};
+
+/**
+ * Register an async channel for a vhost queue
  *
  * @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 config
+ *  Async channel configuration structure
  * @param ops
- *  DMA operation callbacks
+ *  Async channel operation callbacks
  * @return
  *  0 on success, -1 on failures
  */
 __rte_experimental
 int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
-	uint32_t features, struct rte_vhost_async_channel_ops *ops);
+	struct rte_vhost_async_config config,
+	struct rte_vhost_async_channel_ops *ops);
 
 /**
- * unregister a dma channel for vhost
+ * Unregister an async channel for a vhost queue
  *
  * @param vid
- *  vhost device id DMA channel to be detached
+ *  vhost device id async channel to be detached from
  * @param queue_id
- *  vhost queue id DMA channel to be detached
+ *  vhost queue id async channel to be detached from
  * @return
  *  0 on success, -1 on failures
  */

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
@@ -1619,19 +1619,17 @@ 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)
+int
+rte_vhost_async_channel_register(int vid, uint16_t queue_id,
+		struct rte_vhost_async_config config,
+		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;
 
@@ -1640,7 +1638,7 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 	if (unlikely(vq == NULL || !dev->async_copy))
 		return -1;
 
-	if (unlikely(!f.async_inorder)) {
+	if (unlikely(!(config.features & RTE_VHOST_ASYNC_INORDER))) {
 		VHOST_LOG_CONFIG(ERR,
 			"async copy is not supported on non-inorder mode "
 			"(vid %d, qid: %d)\n", vid, queue_id);
@@ -1719,9 +1717,7 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 
 	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_threshold = config.async_threshold;
 
 	vq->async_registered = true;
 
@@ -1731,7 +1727,8 @@ int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
 	return 0;
 }
 
-int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
+int
+rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
 {
 	struct vhost_virtqueue *vq;
 	struct virtio_net *dev = get_device(vid);

diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
@@ -218,9 +218,8 @@ struct vhost_virtqueue {
 	};
 
 	/* vq async features */
-	bool		async_inorder;
 	bool		async_registered;
-	uint16_t	async_threshold;
+	uint32_t	async_threshold;
 
 	int			notif_enable;
 #define VIRTIO_UNINITIALIZED_NOTIF	(-1)