[PATCH net-next v4 4/5] net/mlx5: Consider VLAN interface in MACsec TX steering rules

[Emeel Hakim <ehakim@nvidia.com>]

Offloading MACsec when its configured over VLAN with current MACsec
TX steering rules will wrongly insert MACsec sec tag after inserting
the VLAN header leading to a ETHERNET | SECTAG | VLAN packet when
ETHERNET | VLAN | SECTAG is configured.

The above issue is due to adding the SECTAG by HW which is a later
stage compared to the VLAN header insertion stage.

Detect such a case and adjust TX steering rules to insert the
SECTAG in the correct place by using reformat_param_0 field in
the packet reformat to indicate the offset of SECTAG from end of
the MAC header to account for VLANs in granularity of 4Bytes.

Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
---
 .../net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c   | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c
index 9173b67becef..7fc901a6ec5f 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c
@@ -4,6 +4,7 @@
 #include <net/macsec.h>
 #include <linux/netdevice.h>
 #include <linux/mlx5/qp.h>
+#include <linux/if_vlan.h>
 #include "fs_core.h"
 #include "en/fs.h"
 #include "en_accel/macsec_fs.h"
@@ -508,6 +509,8 @@ static void macsec_fs_tx_del_rule(struct mlx5e_macsec_fs *macsec_fs,
 	macsec_fs_tx_ft_put(macsec_fs);
 }
 
+#define MLX5_REFORMAT_PARAM_ADD_MACSEC_OFFSET_4_BYTES 1
+
 static union mlx5e_macsec_rule *
 macsec_fs_tx_add_rule(struct mlx5e_macsec_fs *macsec_fs,
 		      const struct macsec_context *macsec_ctx,
@@ -553,6 +556,10 @@ macsec_fs_tx_add_rule(struct mlx5e_macsec_fs *macsec_fs,
 	reformat_params.type = MLX5_REFORMAT_TYPE_ADD_MACSEC;
 	reformat_params.size = reformat_size;
 	reformat_params.data = reformatbf;
+
+	if (is_vlan_dev(macsec_ctx->netdev))
+		reformat_params.param_0 = MLX5_REFORMAT_PARAM_ADD_MACSEC_OFFSET_4_BYTES;
+
 	flow_act.pkt_reformat = mlx5_packet_reformat_alloc(macsec_fs->mdev,
 							   &reformat_params,
 							   MLX5_FLOW_NAMESPACE_EGRESS_MACSEC);
-- 
2.21.3