[PATCH nf-next v3 1/3] net/mlx5e: Ignore FLOW_ACTION_PRIORITY on flowtable offload

[Julius Bairaktaris]

The next patch makes the flowtable emit FLOW_ACTION_PRIORITY for flows
with a non-zero skb->priority, which on IPv4 includes the priority
ip_forward() derives from the TOS by default. mlx5 would reject these
rules and stop offloading flows it offloads today.

The eswitch does not use skb->priority for these flows, so accept the
action on flowtable flows and ignore it. tc flower rules with skbedit
priority are still rejected.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Julius Bairaktaris <julius at bairaktaris.de>
---
 .../net/ethernet/mellanox/mlx5/core/Makefile  |  2 +-
 .../mellanox/mlx5/core/en/tc/act/act.c        |  1 +
 .../mellanox/mlx5/core/en/tc/act/act.h        |  1 +
 .../mellanox/mlx5/core/en/tc/act/prio.c       | 22 +++++++++++++++++++
 4 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/prio.c

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/Makefile b/drivers/net/ethernet/mellanox/mlx5/core/Makefile
index 19e50f0d55af..8bd352e7f20d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/Makefile
+++ b/drivers/net/ethernet/mellanox/mlx5/core/Makefile
@@ -54,7 +54,7 @@ mlx5_core-$(CONFIG_MLX5_CLS_ACT)     += en/tc/act/act.o en/tc/act/drop.o en/tc/a
 					en/tc/act/accept.o en/tc/act/mark.o en/tc/act/goto.o \
 					en/tc/act/tun.o en/tc/act/csum.o en/tc/act/pedit.o \
 					en/tc/act/vlan.o en/tc/act/vlan_mangle.o en/tc/act/mpls.o \
-					en/tc/act/mirred.o en/tc/act/mirred_nic.o \
+					en/tc/act/mirred.o en/tc/act/mirred_nic.o en/tc/act/prio.o \
 					en/tc/act/ct.o en/tc/act/sample.o en/tc/act/ptype.o \
 					en/tc/act/redirect_ingress.o en/tc/act/police.o
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.c b/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.c
index 0380a04c3691..91a3bab5e498 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.c
@@ -23,6 +23,7 @@ static struct mlx5e_tc_act *tc_acts_fdb[NUM_FLOW_ACTIONS] = {
 	[FLOW_ACTION_ADD] = &mlx5e_tc_act_pedit,
 	[FLOW_ACTION_CSUM] = &mlx5e_tc_act_csum,
 	[FLOW_ACTION_PTYPE] = &mlx5e_tc_act_ptype,
+	[FLOW_ACTION_PRIORITY] = &mlx5e_tc_act_prio,
 	[FLOW_ACTION_SAMPLE] = &mlx5e_tc_act_sample,
 	[FLOW_ACTION_POLICE] = &mlx5e_tc_act_police,
 	[FLOW_ACTION_CT] = &mlx5e_tc_act_ct,
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.h b/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.h
index 2e528b2c34d6..bacbc862970e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/act.h
@@ -81,6 +81,7 @@ extern struct mlx5e_tc_act mlx5e_tc_act_goto;
 extern struct mlx5e_tc_act mlx5e_tc_act_tun_encap;
 extern struct mlx5e_tc_act mlx5e_tc_act_tun_decap;
 extern struct mlx5e_tc_act mlx5e_tc_act_csum;
+extern struct mlx5e_tc_act mlx5e_tc_act_prio;
 extern struct mlx5e_tc_act mlx5e_tc_act_pedit;
 extern struct mlx5e_tc_act mlx5e_tc_act_vlan;
 extern struct mlx5e_tc_act mlx5e_tc_act_vlan_mangle;
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/prio.c b/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/prio.c
new file mode 100644
index 000000000000..2a047059574b
--- /dev/null
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/tc/act/prio.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+
+#include "act.h"
+#include "en/tc_priv.h"
+
+static int
+tc_act_parse_prio(struct mlx5e_tc_act_parse_state *parse_state,
+		  const struct flow_action_entry *act,
+		  struct mlx5e_priv *priv,
+		  struct mlx5_flow_attr *attr)
+{
+	/* The eswitch does not apply skb->priority to flowtable flows. */
+	if (mlx5e_is_ft_flow(parse_state->flow))
+		return 0;
+
+	NL_SET_ERR_MSG_MOD(parse_state->extack, "skbedit priority is not supported");
+	return -EOPNOTSUPP;
+}
+
+struct mlx5e_tc_act mlx5e_tc_act_prio = {
+	.parse_action = tc_act_parse_prio,
+};
-- 
2.53.0