[PATCH v1] net/mlx5: adapt parse graph header length limitation

[Rongwei Liu <rongweil@nvidia.com>]

Firmware exports the parse graph header length capability via
hca_attr and the current value is 6.
The user must specify the header length field via field_size.
Field size implies the mask implicitly as 2^field_size-1

1. If field_size is bigger than 6, PMD needs to add an extra offset
internally, let HW only parses the 6 LSBs as length.
           length
|--------|--------|--------|--------|
The actual header length offset 8 doesn't work well with new
firmware, only the bits 8-13 are read and parsed as a length field.
Need to change the offset to 10 (8 + 2) internally. Field mask can't
be bigger than 0x3F (2^6-1).

2. If filed_size is smaller that 6, PMD needs to subtract an offset to
fit 6 bits exactly.
         length
|--------|----|------------|--------|
The actual header length offset 8 doesn't work well with new
firmware because firmware will read two more bits from the next field.
Need to change the offset to 6 (8 -2) internally.

Signed-off-by: Rongwei Liu <rongweil@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 drivers/net/mlx5/mlx5.c           |  3 +++
 drivers/net/mlx5/mlx5_flow_flex.c | 22 +++++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index a75fa1b7f0..f9aea13187 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -1057,6 +1057,7 @@ mlx5_alloc_srh_flex_parser(struct rte_eth_dev *dev)
 	uint32_t ids[MLX5_GRAPH_NODE_SAMPLE_NUM];
 	struct mlx5_priv *priv = dev->data->dev_private;
 	struct mlx5_common_dev_config *config = &priv->sh->cdev->config;
+	struct mlx5_hca_flex_attr *attr = &priv->sh->cdev->config.hca_attr.flex;
 	void *fp = NULL, *ibv_ctx = priv->sh->cdev->ctx;
 	int ret;
 
@@ -1079,6 +1080,8 @@ mlx5_alloc_srh_flex_parser(struct rte_eth_dev *dev)
 	node.header_length_field_shift = 0x3;
 	/* Header length is the 2nd byte. */
 	node.header_length_field_offset = 0x8;
+	if (attr->header_length_mask_width < 8)
+		node.header_length_field_offset += 8 - attr->header_length_mask_width;
 	node.header_length_field_mask = 0xF;
 	/* One byte next header protocol. */
 	node.next_header_field_size = 0x8;
diff --git a/drivers/net/mlx5/mlx5_flow_flex.c b/drivers/net/mlx5/mlx5_flow_flex.c
index 4f66b7dd1a..4ae03a23f1 100644
--- a/drivers/net/mlx5/mlx5_flow_flex.c
+++ b/drivers/net/mlx5/mlx5_flow_flex.c
@@ -484,6 +484,14 @@ mlx5_flex_translate_length(struct mlx5_hca_flex_attr *attr,
 			return rte_flow_error_set
 				(error, EINVAL, RTE_FLOW_ERROR_TYPE_ITEM, NULL,
 				 "unsupported header length field mode (OFFSET)");
+		if (!field->field_size)
+			return rte_flow_error_set
+				(error, EINVAL, RTE_FLOW_ERROR_TYPE_ITEM, NULL,
+				 "field size is a must for offset mode");
+		if (field->field_size + field->offset_base < attr->header_length_mask_width)
+			return rte_flow_error_set
+				(error, EINVAL, RTE_FLOW_ERROR_TYPE_ITEM, NULL,
+				 "field size plus offset_base is too small");
 		node->header_length_mode = MLX5_GRAPH_NODE_LEN_FIELD;
 		if (field->offset_mask == 0 ||
 		    !rte_is_power_of_2(field->offset_mask + 1))
@@ -539,9 +547,21 @@ mlx5_flex_translate_length(struct mlx5_hca_flex_attr *attr,
 			return rte_flow_error_set
 				(error, EINVAL, RTE_FLOW_ERROR_TYPE_ITEM, NULL,
 				 "header length field shift exceeds limit");
-		node->header_length_field_shift	= field->offset_shift;
+		node->header_length_field_shift = field->offset_shift;
 		node->header_length_field_offset = field->offset_base;
 	}
+	if (field->field_mode == FIELD_MODE_OFFSET) {
+		if (field->field_size > attr->header_length_mask_width) {
+			node->header_length_field_offset +=
+				field->field_size - attr->header_length_mask_width;
+		} else if (field->field_size < attr->header_length_mask_width) {
+			node->header_length_field_offset -=
+				attr->header_length_mask_width - field->field_size;
+			node->header_length_field_mask =
+					RTE_MIN(node->header_length_field_mask,
+						(1u << field->field_size) - 1);
+		}
+	}
 	return 0;
 }
 
-- 
2.27.0