net/mlx5: HWS, do not initialize native API queues

HWS has two types of APIs:
 - Native: fastest and slimmest, async API.
   The user of this API is required to manage rule handles memory,
   and to poll for completion for each rule.
 - BWC: backward compatible API, similar semantics to SWS API.
   This layer is implemented above native API and it does all
   the work for the user, so that it is easy to switch between
   SWS and HWS.

Right now the existing users of HWS require only BWC API.
Therefore, in order to not waste resources, this patch disables
send queues allocation for native API.

If in the future support for faster HWS rule insertion will be required
(such as for Connection Tracking), native queues can be enabled.

Signed-off-by: Yevgeny Kliteynik <[email protected]>
Reviewed-by: Itamar Gozlan <[email protected]>
Reviewed-by: Mark Bloch <[email protected]>
Signed-off-by: Tariq Toukan <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kliteyn

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.h

@@ -60,9 +60,11 @@ void mlx5hws_bwc_rule_fill_attr(struct mlx5hws_bwc_matcher *bwc_matcher,
 static inline u16 mlx5hws_bwc_queues(struct mlx5hws_context *ctx)
 {
 	/* Besides the control queue, half of the queues are
-	 * reguler HWS queues, and the other half are BWC queues.
+	 * regular HWS queues, and the other half are BWC queues.
 	 */
-	return (ctx->queues - 1) / 2;
+	if (mlx5hws_context_bwc_supported(ctx))
+		return (ctx->queues - 1) / 2;
+	return 0;
 }
 
 static inline u16 mlx5hws_bwc_get_queue_id(struct mlx5hws_context *ctx, u16 idx)

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/context.c

@@ -161,8 +161,10 @@ static int hws_context_init_hws(struct mlx5hws_context *ctx,
 	if (ret)
 		goto uninit_pd;
 
-	if (attr->bwc)
-		ctx->flags |= MLX5HWS_CONTEXT_FLAG_BWC_SUPPORT;
+	/* Context has support for backward compatible API,
+	 * and does not have support for native HWS API.
+	 */
+	ctx->flags |= MLX5HWS_CONTEXT_FLAG_BWC_SUPPORT;
 
 	ret = mlx5hws_send_queues_open(ctx, attr->queues, attr->queue_size);
 	if (ret)

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/context.h

@@ -8,6 +8,7 @@ enum mlx5hws_context_flags {
 	MLX5HWS_CONTEXT_FLAG_HWS_SUPPORT = 1 << 0,
 	MLX5HWS_CONTEXT_FLAG_PRIVATE_PD = 1 << 1,
 	MLX5HWS_CONTEXT_FLAG_BWC_SUPPORT = 1 << 2,
+	MLX5HWS_CONTEXT_FLAG_NATIVE_SUPPORT = 1 << 3,
 };
 
 enum mlx5hws_context_shared_stc_type {
@@ -58,6 +59,11 @@ static inline bool mlx5hws_context_bwc_supported(struct mlx5hws_context *ctx)
 	return ctx->flags & MLX5HWS_CONTEXT_FLAG_BWC_SUPPORT;
 }
 
+static inline bool mlx5hws_context_native_supported(struct mlx5hws_context *ctx)
+{
+	return ctx->flags & MLX5HWS_CONTEXT_FLAG_NATIVE_SUPPORT;
+}
+
 bool mlx5hws_context_cap_dynamic_reparse(struct mlx5hws_context *ctx);
 
 u8 mlx5hws_context_get_reparse_mode(struct mlx5hws_context *ctx);

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h

@@ -70,7 +70,6 @@ enum mlx5hws_send_queue_actions {
 struct mlx5hws_context_attr {
 	u16 queues;
 	u16 queue_size;
-	bool bwc; /* add support for backward compatible API*/
 };
 
 struct mlx5hws_table_attr {

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/send.c

@@ -898,6 +898,9 @@ static int mlx5hws_send_ring_open(struct mlx5hws_context *ctx,
 
 static void mlx5hws_send_queue_close(struct mlx5hws_send_engine *queue)
 {
+	if (!queue->num_entries)
+		return; /* this queue wasn't initialized */
+
 	hws_send_ring_close(queue);
 	kfree(queue->completed.entries);
 }
@@ -1005,7 +1008,7 @@ int mlx5hws_send_queues_open(struct mlx5hws_context *ctx,
 			     u16 queue_size)
 {
 	int err = 0;
-	u32 i;
+	int i = 0;
 
 	/* Open one extra queue for control path */
 	ctx->queues = queues + 1;
@@ -1021,7 +1024,13 @@ int mlx5hws_send_queues_open(struct mlx5hws_context *ctx,
 		goto free_bwc_locks;
 	}
 
-	for (i = 0; i < ctx->queues; i++) {
+	/* If native API isn't supported, skip the unused native queues:
+	 * initialize BWC queues and control queue only.
+	 */
+	if (!mlx5hws_context_native_supported(ctx))
+		i = mlx5hws_bwc_get_queue_id(ctx, 0);
+
+	for (; i < ctx->queues; i++) {
 		err = mlx5hws_send_queue_open(ctx, &ctx->send_queue[i], queue_size);
 		if (err)
 			goto close_send_queues;