[dpdk-dev] [PATCH 2/2] net/mlx5: add decap enable device argument

[Suanming Mou]

There are some limitations on the some NICs (at least on ConnectX-6DX
and BlueField2) with supporting FCS (frame checksum) scattering for
the  tunnel decapsulated packets.

For the case only one of the features can be supported in the same time,
and the new devarg "decap_en" is introduced to provide the choice to the
users.

If FCS scattering feature is not supposed to be engaged by application,
this new devarg should be specified as "decap_en=0", forcing the FCS
feature enable and rejecting tunnel decap actions in the rte_flow engine.
If FCS scatter is not needed and application supposes to use tunnel
decapsulation in rte_flow, the devarg can be omitted or set to non-zero
value (this is default settings).

Signed-off-by: Suanming Mou <suanmingm at mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo at mellanox.com>
---
 doc/guides/nics/mlx5.rst         | 10 ++++++++++
 drivers/net/mlx5/linux/mlx5_os.c | 12 ++++++++++--
 drivers/net/mlx5/mlx5.c          |  6 ++++++
 drivers/net/mlx5/mlx5.h          |  1 +
 drivers/net/mlx5/mlx5_flow_dv.c  |  5 +++++
 5 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 97261d6..ccf38b6 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -884,6 +884,16 @@ Driver options
 
   By default, the PMD will set this value to 0.
 
+- ``decap_en`` parameter [int]
+
+  The new devarg ``decap_en`` is introduced to provide the choice to the NICs
+  which does not support FCS (frame checksum) scattering for the tunnel
+  decapsulated packets. By set the devarg value 0 to force the FCS feature
+  enable and rejecting tunnel decap actions in the rte_flow engine for these
+  special NICs.
+
+  By default, the PMD will set this value to 1.
+
 .. _mlx5_firmware_config:
 
 Firmware configuration
diff --git a/drivers/net/mlx5/linux/mlx5_os.c b/drivers/net/mlx5/linux/mlx5_os.c
index 2dc57b2..37420cb 100644
--- a/drivers/net/mlx5/linux/mlx5_os.c
+++ b/drivers/net/mlx5/linux/mlx5_os.c
@@ -780,8 +780,6 @@
 		(config.hw_vlan_strip ? "" : "not "));
 	config.hw_fcs_strip = !!(sh->device_attr.raw_packet_caps &
 				 IBV_RAW_PACKET_CAP_SCATTER_FCS);
-	DRV_LOG(DEBUG, "FCS stripping configuration is %ssupported",
-		(config.hw_fcs_strip ? "" : "not "));
 #if defined(HAVE_IBV_WQ_FLAG_RX_END_PADDING)
 	hw_padding = !!sh->device_attr.rx_pad_end_addr_align;
 #elif defined(HAVE_IBV_WQ_FLAGS_PCI_WRITE_END_PADDING)
@@ -879,6 +877,15 @@
 		}
 #endif
 	}
+	/*
+	 * If HW has bug working with tunnel packet decapsulation and
+	 * scatter FCS, and decapsulation is needed, clear the hw_fcs_strip
+	 * bit. Then DEV_RX_OFFLOAD_KEEP_CRC bit will not be set anymore.
+	 */
+	if (config.hca_attr.scatter_fcs_w_decap_disable && config.decap_en)
+		config.hw_fcs_strip = 0;
+	DRV_LOG(DEBUG, "FCS stripping configuration is %ssupported",
+		(config.hw_fcs_strip ? "" : "not "));
 	if (config.mprq.enabled && mprq) {
 		if (config.mprq.stride_num_n &&
 		    (config.mprq.stride_num_n > mprq_max_stride_num_n ||
@@ -1652,6 +1659,7 @@
 		},
 		.dv_esw_en = 1,
 		.dv_flow_en = 1,
+		.decap_en = 1,
 		.log_hp_size = MLX5_ARG_UNSET,
 	};
 	/* Device specific configuration. */
diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 0c654ed..9daacaf 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -167,6 +167,9 @@
 /* Flow memory reclaim mode. */
 #define MLX5_RECLAIM_MEM "reclaim_mem_mode"
 
+/* Decap will be used or not. */
+#define MLX5_DECAP_EN "decap_en"
+
 static const char *MZ_MLX5_PMD_SHARED_DATA = "mlx5_pmd_shared_data";
 
 /* Shared memory between primary and secondary processes. */
@@ -1374,6 +1377,8 @@ struct mlx5_dev_ctx_shared *
 			return -rte_errno;
 		}
 		config->reclaim_mode = tmp;
+	} else if (strcmp(MLX5_DECAP_EN, key) == 0) {
+		config->decap_en = !!tmp;
 	} else {
 		DRV_LOG(WARNING, "%s: unknown parameter", key);
 		rte_errno = EINVAL;
@@ -1430,6 +1435,7 @@ struct mlx5_dev_ctx_shared *
 		MLX5_CLASS_ARG_NAME,
 		MLX5_HP_BUF_SIZE,
 		MLX5_RECLAIM_MEM,
+		MLX5_DECAP_EN,
 		NULL,
 	};
 	struct rte_kvargs *kvlist;
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index 46e66eb..c7b6a84 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -216,6 +216,7 @@ struct mlx5_dev_config {
 	unsigned int devx:1; /* Whether devx interface is available or not. */
 	unsigned int dest_tir:1; /* Whether advanced DR API is available. */
 	unsigned int reclaim_mode:2; /* Memory reclaim mode. */
+	unsigned int decap_en:1; /* Whether decap will be used or not. */
 	struct {
 		unsigned int enabled:1; /* Whether MPRQ is enabled. */
 		unsigned int stride_num_n; /* Number of strides. */
diff --git a/drivers/net/mlx5/mlx5_flow_dv.c b/drivers/net/mlx5/mlx5_flow_dv.c
index 8b5b683..37db7c5 100644
--- a/drivers/net/mlx5/mlx5_flow_dv.c
+++ b/drivers/net/mlx5/mlx5_flow_dv.c
@@ -2428,6 +2428,11 @@ struct field_modify_info modify_tcp[] = {
 {
 	const struct mlx5_priv *priv = dev->data->dev_private;
 
+	if (priv->config.hca_attr.scatter_fcs_w_decap_disable &&
+	    !priv->config.decap_en)
+		return rte_flow_error_set(error, ENOTSUP,
+					  RTE_FLOW_ERROR_TYPE_ACTION, NULL,
+					  "decap is not enabled");
 	if (action_flags & MLX5_FLOW_XCAP_ACTIONS)
 		return rte_flow_error_set(error, ENOTSUP,
 					  RTE_FLOW_ERROR_TYPE_ACTION, NULL,
-- 
1.8.3.1