[dpdk-dev] [PATCH v4 2/3] vhost: rework async configuration struct

[Jiayu Hu <jiayu.hu@intel.com>]

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 <jiayu.hu@intel.com>
---
 doc/guides/prog_guide/vhost_lib.rst | 19 +++++++++++--------
 examples/vhost/main.c               |  8 ++++----
 lib/vhost/rte_vhost_async.h         | 35 +++++++++++++++++------------------
 lib/vhost/vhost.c                   | 13 +++++--------
 4 files changed, 37 insertions(+), 38 deletions(-)

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index d18fb98..affdc57 100644
--- 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
+  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
index d2179ea..9cd855a 100644
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -1468,7 +1468,7 @@ 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) {
@@ -1476,11 +1476,11 @@ new_device(int vid)
 			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
index 6faa31f..c93490d 100644
--- a/lib/vhost/rte_vhost_async.h
+++ b/lib/vhost/rte_vhost_async.h
@@ -93,18 +93,20 @@ struct async_inflight_info {
 };
 
 /**
- *  dma channel feature bit definition
+ *  dma 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_FEATURE_UNKNOWN = 0U,
+	RTE_VHOST_ASYNC_INORDER = 1U << 0,
+};
+
+/**
+ *  dma channel configuration
+ */
+struct rte_vhost_async_config {
+	uint32_t async_threshold;
+	uint32_t features;
+	uint32_t resvd[2];
 };
 
 /**
@@ -114,12 +116,8 @@ struct rte_vhost_async_features {
  *  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
+ *  DMA channel configuration structure
  * @param ops
  *  DMA operation callbacks
  * @return
@@ -127,7 +125,8 @@ struct rte_vhost_async_features {
  */
 __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
diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 53a470f..a20f05a 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1620,18 +1620,15 @@ int rte_vhost_extern_callback_register(int vid,
 }
 
 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)
 {
 	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 +1637,7 @@ 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);
@@ -1720,8 +1717,8 @@ 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_inorder = true;
+	vq->async_threshold = config.async_threshold;
 
 	vq->async_registered = true;
 
-- 
2.7.4