[PATCH net-next 4/4] net/mlx5: HWS, handle modify header actions dependency

[Tariq Toukan <tariqt@nvidia.com>]

From: Yevgeny Kliteynik <kliteyn@nvidia.com>

Having adjacent accelerated modify header actions (so-called
pattern-argument actions) may result in inconsistent outcome.
These inconsistencies can take the form of writes to the same
field or a read coupled with a write to the same field. The
solution is to detect such dependencies and insert nops between
the offending actions.

The existing implementation had a few issues, which pretty much
required a complete rewrite of the code that handles these
dependencies.

In the new implementation we're doing the following:

* Checking any two adjacent actions for conflicts (not just
  odd-even pairs).
* Marking 'set' and 'add' action fields as destination, rather
  than source, for the purposes of checking for conflicts.
* Checking all types of actions ('add', 'set', 'copy') for
  dependencies.
* Managing offsets of the args in the buffer - copy the action
  args to the right place in the buffer.
* Checking that after inserting nops we're still within the number
  of supported actions - return an error otherwise.

Signed-off-by: Vlad Dogaru <vdogaru@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../mellanox/mlx5/core/steering/hws/action.c  | 21 ++++--
 .../mellanox/mlx5/core/steering/hws/pat_arg.c | 74 ++++++++++---------
 .../mellanox/mlx5/core/steering/hws/pat_arg.h |  6 +-
 3 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/action.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/action.c
index 64d115feef2c..fb62f3bc4bd4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/action.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/action.c
@@ -1190,14 +1190,15 @@ hws_action_create_modify_header_hws(struct mlx5hws_action *action,
 				    struct mlx5hws_action_mh_pattern *pattern,
 				    u32 log_bulk_size)
 {
+	u16 num_actions, max_mh_actions = 0, hw_max_actions;
 	struct mlx5hws_context *ctx = action->ctx;
-	u16 num_actions, max_mh_actions = 0;
 	int i, ret, size_in_bytes;
 	u32 pat_id, arg_id = 0;
 	__be64 *new_pattern;
 	size_t pat_max_sz;
 
 	pat_max_sz = MLX5HWS_ARG_CHUNK_SIZE_MAX * MLX5HWS_ARG_DATA_SIZE;
+	hw_max_actions = pat_max_sz / MLX5HWS_MODIFY_ACTION_SIZE;
 	size_in_bytes = pat_max_sz * sizeof(__be64);
 	new_pattern = kcalloc(num_of_patterns, size_in_bytes, GFP_KERNEL);
 	if (!new_pattern)
@@ -1211,10 +1212,14 @@ hws_action_create_modify_header_hws(struct mlx5hws_action *action,
 
 		cur_num_actions = pattern[i].sz / MLX5HWS_MODIFY_ACTION_SIZE;
 
-		mlx5hws_pat_calc_nop(pattern[i].data, cur_num_actions,
-				     pat_max_sz / MLX5HWS_MODIFY_ACTION_SIZE,
-				     &new_num_actions, &nop_locations,
-				     &new_pattern[i * pat_max_sz]);
+		ret = mlx5hws_pat_calc_nop(pattern[i].data, cur_num_actions,
+					   hw_max_actions, &new_num_actions,
+					   &nop_locations,
+					   &new_pattern[i * pat_max_sz]);
+		if (ret) {
+			mlx5hws_err(ctx, "Too many actions after nop insertion\n");
+			goto free_new_pat;
+		}
 
 		action[i].modify_header.nop_locations = nop_locations;
 		action[i].modify_header.num_of_actions = new_num_actions;
@@ -2116,10 +2121,12 @@ static void hws_action_modify_write(struct mlx5hws_send_engine *queue,
 		if (unlikely(!new_arg_data))
 			return;
 
-		for (i = 0, j = 0; i < num_of_actions; i++, j++) {
-			memcpy(&new_arg_data[j], arg_data, MLX5HWS_MODIFY_ACTION_SIZE);
+		for (i = 0, j = 0; j < num_of_actions; i++, j++) {
 			if (BIT(i) & nop_locations)
 				j++;
+			memcpy(&new_arg_data[j * MLX5HWS_MODIFY_ACTION_SIZE],
+			       &arg_data[i * MLX5HWS_MODIFY_ACTION_SIZE],
+			       MLX5HWS_MODIFY_ACTION_SIZE);
 		}
 	}
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
index 78de19c074a7..51e4c551e0ef 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
@@ -490,8 +490,8 @@ hws_action_modify_get_target_fields(u8 action_type, __be64 *pattern,
 	switch (action_type) {
 	case MLX5_ACTION_TYPE_SET:
 	case MLX5_ACTION_TYPE_ADD:
-		*src_field = MLX5_GET(set_action_in, pattern, field);
-		*dst_field = INVALID_FIELD;
+		*src_field = INVALID_FIELD;
+		*dst_field = MLX5_GET(set_action_in, pattern, field);
 		break;
 	case MLX5_ACTION_TYPE_COPY:
 		*src_field = MLX5_GET(copy_action_in, pattern, src_field);
@@ -522,57 +522,59 @@ bool mlx5hws_pat_verify_actions(struct mlx5hws_context *ctx, __be64 pattern[], s
 	return true;
 }
 
-void mlx5hws_pat_calc_nop(__be64 *pattern, size_t num_actions,
-			  size_t max_actions, size_t *new_size,
-			  u32 *nop_locations, __be64 *new_pat)
+int mlx5hws_pat_calc_nop(__be64 *pattern, size_t num_actions,
+			 size_t max_actions, size_t *new_size,
+			 u32 *nop_locations, __be64 *new_pat)
 {
-	u16 prev_src_field = 0, prev_dst_field = 0;
+	u16 prev_src_field = INVALID_FIELD, prev_dst_field = INVALID_FIELD;
 	u16 src_field, dst_field;
 	u8 action_type;
+	bool dependent;
 	size_t i, j;
 
 	*new_size = num_actions;
 	*nop_locations = 0;
 
 	if (num_actions == 1)
-		return;
+		return 0;
 
 	for (i = 0, j = 0; i < num_actions; i++, j++) {
-		action_type = MLX5_GET(set_action_in, &pattern[i], action_type);
+		if (j >= max_actions)
+			return -EINVAL;
 
+		action_type = MLX5_GET(set_action_in, &pattern[i], action_type);
 		hws_action_modify_get_target_fields(action_type, &pattern[i],
 						    &src_field, &dst_field);
-		if (i % 2) {
-			if (action_type == MLX5_ACTION_TYPE_COPY &&
-			    (prev_src_field == src_field ||
-			     prev_dst_field == dst_field)) {
-				/* need Nop */
-				*new_size += 1;
-				*nop_locations |= BIT(i);
-				memset(&new_pat[j], 0, MLX5HWS_MODIFY_ACTION_SIZE);
-				MLX5_SET(set_action_in, &new_pat[j],
-					 action_type,
-					 MLX5_MODIFICATION_TYPE_NOP);
-				j++;
-			} else if (prev_src_field == src_field) {
-				/* need Nop */
-				*new_size += 1;
-				*nop_locations |= BIT(i);
-				MLX5_SET(set_action_in, &new_pat[j],
-					 action_type,
-					 MLX5_MODIFICATION_TYPE_NOP);
-				j++;
-			}
-		}
-		memcpy(&new_pat[j], &pattern[i], MLX5HWS_MODIFY_ACTION_SIZE);
-		/* check if no more space */
-		if (j > max_actions) {
-			*new_size = num_actions;
-			*nop_locations = 0;
-			return;
+
+		/* For every action, look at it and the previous one. The two
+		 * actions are dependent if:
+		 */
+		dependent =
+			(i > 0) &&
+			/* At least one of the actions is a write and */
+			(dst_field != INVALID_FIELD ||
+			 prev_dst_field != INVALID_FIELD) &&
+			/* One reads from the other's source */
+			(dst_field == prev_src_field ||
+			 src_field == prev_dst_field ||
+			 /* Or both write to the same destination */
+			 dst_field == prev_dst_field);
+
+		if (dependent) {
+			*new_size += 1;
+			*nop_locations |= BIT(i);
+			memset(&new_pat[j], 0, MLX5HWS_MODIFY_ACTION_SIZE);
+			MLX5_SET(set_action_in, &new_pat[j], action_type,
+				 MLX5_MODIFICATION_TYPE_NOP);
+			j++;
+			if (j >= max_actions)
+				return -EINVAL;
 		}
 
+		memcpy(&new_pat[j], &pattern[i], MLX5HWS_MODIFY_ACTION_SIZE);
 		prev_src_field = src_field;
 		prev_dst_field = dst_field;
 	}
+
+	return 0;
 }
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.h b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.h
index 91bd2572a341..7fbd8dc7aa18 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.h
@@ -96,7 +96,7 @@ int mlx5hws_arg_write_inline_arg_data(struct mlx5hws_context *ctx,
 				      u8 *arg_data,
 				      size_t data_size);
 
-void mlx5hws_pat_calc_nop(__be64 *pattern, size_t num_actions,
-			  size_t max_actions, size_t *new_size,
-			  u32 *nop_locations, __be64 *new_pat);
+int mlx5hws_pat_calc_nop(__be64 *pattern, size_t num_actions,
+			 size_t max_actions, size_t *new_size,
+			 u32 *nop_locations, __be64 *new_pat);
 #endif /* MLX5HWS_PAT_ARG_H_ */
-- 
2.31.1