netdev - [PATCH net-next 1/6] mlxsw: Trap ARP packets at layer 2 instead of layer 3

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Message-ID: <b2a2cc607a1f4cb96c10bd3b0b0244ba3117fd2e.1742224300.git.petrm@nvidia.com>
Date: Mon, 17 Mar 2025 18:37:26 +0100
From: Petr Machata <petrm@...dia.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Simon Horman <horms@...nel.org>, Andrew Lunn
	<andrew+netdev@...n.ch>, <netdev@...r.kernel.org>
CC: Ido Schimmel <idosch@...dia.com>, Petr Machata <petrm@...dia.com>, "Amit
 Cohen" <amcohen@...dia.com>, <mlxsw@...dia.com>
Subject: [PATCH net-next 1/6] mlxsw: Trap ARP packets at layer 2 instead of layer 3

From: Amit Cohen <amcohen@...dia.com>

Next patch will set the same hardware domain for all bridge ports,
including VXLAN, to prevent packets from being forwarded by software when
they were already forwarded by hardware.

ARP packets are not flooded by hardware to VXLAN, so software should handle
such flooding. When hardware domain of VXLAN device will be changed, ARP
packets which are trapped and marked with offload_fwd_mark will not be
flooded to VXLAN also in software, which will break VXLAN traffic.

To prevent such breaking, trap ARP packets at layer 2 and don't mark them
as L2-forwarded in hardware, then flooding ARP packets will be done only
in software, and VXLAN will send ARP packets.

Remove NVE_ENCAP_ARP which is no longer needed, as now ARP packets are
trapped when they enter the device.

Signed-off-by: Amit Cohen <amcohen@...dia.com>
Reviewed-by: Petr Machata <petrm@...dia.com>
Reviewed-by: Ido Schimmel <idosch@...dia.com>
Signed-off-by: Petr Machata <petrm@...dia.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c      |  2 --
 drivers/net/ethernet/mellanox/mlxsw/spectrum_trap.c | 12 ++++++------
 drivers/net/ethernet/mellanox/mlxsw/trap.h          |  5 ++---
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index c7e6a3258244..2bc8a3dbc836 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -2409,8 +2409,6 @@ static const struct mlxsw_listener mlxsw_sp_listener[] = {
 	/* Multicast Router Traps */
 	MLXSW_SP_RXL_MARK(ACL1, TRAP_TO_CPU, MULTICAST, false),
 	MLXSW_SP_RXL_L3_MARK(ACL2, TRAP_TO_CPU, MULTICAST, false),
-	/* NVE traps */
-	MLXSW_SP_RXL_MARK(NVE_ENCAP_ARP, TRAP_TO_CPU, NEIGH_DISCOVERY, false),
 };
 
 static const struct mlxsw_listener mlxsw_sp1_listener[] = {
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_trap.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_trap.c
index 1f9c1c86839f..b5c3f789c685 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_trap.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_trap.c
@@ -959,18 +959,18 @@ static const struct mlxsw_sp_trap_item mlxsw_sp_trap_items_arr[] = {
 	},
 	{
 		.trap = MLXSW_SP_TRAP_CONTROL(ARP_REQUEST, NEIGH_DISCOVERY,
-					      MIRROR),
+					      TRAP),
 		.listeners_arr = {
-			MLXSW_SP_RXL_MARK(ROUTER_ARPBC, NEIGH_DISCOVERY,
-					  TRAP_TO_CPU, false),
+			MLXSW_SP_RXL_NO_MARK(ARPBC, NEIGH_DISCOVERY,
+					     TRAP_TO_CPU, false),
 		},
 	},
 	{
 		.trap = MLXSW_SP_TRAP_CONTROL(ARP_RESPONSE, NEIGH_DISCOVERY,
-					      MIRROR),
+					      TRAP),
 		.listeners_arr = {
-			MLXSW_SP_RXL_MARK(ROUTER_ARPUC, NEIGH_DISCOVERY,
-					  TRAP_TO_CPU, false),
+			MLXSW_SP_RXL_NO_MARK(ARPUC, NEIGH_DISCOVERY,
+					     TRAP_TO_CPU, false),
 		},
 	},
 	{
diff --git a/drivers/net/ethernet/mellanox/mlxsw/trap.h b/drivers/net/ethernet/mellanox/mlxsw/trap.h
index 83477c8e6971..80ee5c4825dc 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/trap.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/trap.h
@@ -29,6 +29,8 @@ enum {
 	MLXSW_TRAP_ID_FDB_MISMATCH = 0x3B,
 	MLXSW_TRAP_ID_FID_MISS = 0x3D,
 	MLXSW_TRAP_ID_DECAP_ECN0 = 0x40,
+	MLXSW_TRAP_ID_ARPBC = 0x50,
+	MLXSW_TRAP_ID_ARPUC = 0x51,
 	MLXSW_TRAP_ID_MTUERROR = 0x52,
 	MLXSW_TRAP_ID_TTLERROR = 0x53,
 	MLXSW_TRAP_ID_LBERROR = 0x54,
@@ -66,13 +68,10 @@ enum {
 	MLXSW_TRAP_ID_HOST_MISS_IPV6 = 0x92,
 	MLXSW_TRAP_ID_IPIP_DECAP_ERROR = 0xB1,
 	MLXSW_TRAP_ID_NVE_DECAP_ARP = 0xB8,
-	MLXSW_TRAP_ID_NVE_ENCAP_ARP = 0xBD,
 	MLXSW_TRAP_ID_IPV4_BFD = 0xD0,
 	MLXSW_TRAP_ID_IPV6_BFD = 0xD1,
 	MLXSW_TRAP_ID_ROUTER_ALERT_IPV4 = 0xD6,
 	MLXSW_TRAP_ID_ROUTER_ALERT_IPV6 = 0xD7,
-	MLXSW_TRAP_ID_ROUTER_ARPBC = 0xE0,
-	MLXSW_TRAP_ID_ROUTER_ARPUC = 0xE1,
 	MLXSW_TRAP_ID_DISCARD_NON_ROUTABLE = 0x11A,
 	MLXSW_TRAP_ID_DISCARD_ROUTER2 = 0x130,
 	MLXSW_TRAP_ID_DISCARD_ROUTER3 = 0x131,
-- 
2.47.0