mlxsw: Add specific trap for packets routed via invalid nexthops

Currently, mlxsw does not differentiate between these two cases of
routes with invalid nexthops:

1. Nexthops whose nexthop device is a mlxsw upper (has a RIF), but whose
neighbour could not be resolved

2. Nexthops whose nexthop device is not a mlxsw upper (e.g., management
interface)

Up until now this did not matter and mlxsw trapped packets for both
cases using the same trap ID. However, packets that should have been
routed in hardware (case 1), but incurred a problem are considered
exceptions and should be reported to the user. The two cases should
therefore be split between two different trap IDs.

Allocate a new adjacency entry during initialization and upon the
insertion of the first route with an invalid mlxsw nexthop, program this
entry to discard packets. Packets hitting this entry will be reported
using new trap ID - "DISCARD_ROUTER3".

In the future, the entry could be written during initialization, but
currently firmware requires a valid RIF, which is not available at this
stage.
Signed-off-by: Amit Cohen <amitc@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -4528,6 +4528,8 @@ static const struct mlxsw_listener mlxsw_sp_listener[] = {
 	MLXSW_SP_RXL_MARK(IPV6_OSPF, TRAP_TO_CPU, OSPF, false),
 	MLXSW_SP_RXL_MARK(IPV6_DHCP, TRAP_TO_CPU, DHCP, false),
 	MLXSW_SP_RXL_MARK(RTR_INGRESS0, TRAP_TO_CPU, REMOTE_ROUTE, false),
+	MLXSW_SP_RXL_MARK(DISCARD_ROUTER3, TRAP_EXCEPTION_TO_CPU, REMOTE_ROUTE,
+			  false),
 	MLXSW_SP_RXL_MARK(IPV4_BGP, TRAP_TO_CPU, BGP, false),
 	MLXSW_SP_RXL_MARK(IPV6_BGP, TRAP_TO_CPU, BGP, false),
 	MLXSW_SP_RXL_MARK(L3_IPV6_ROUTER_SOLICITATION, TRAP_TO_CPU, IPV6_ND,

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -77,6 +77,7 @@ struct mlxsw_sp_router {
 	struct notifier_block inet6addr_nb;
 	const struct mlxsw_sp_rif_ops **rif_ops_arr;
 	const struct mlxsw_sp_ipip_ops **ipip_ops_arr;
+	u32 adj_discard_index;
 };
 
 struct mlxsw_sp_rif {
@@ -4197,15 +4198,31 @@ mlxsw_sp_fib_entry_ralue_pack(char *ralue_pl,
 	}
 }
 
+static int mlxsw_sp_adj_discard_write(struct mlxsw_sp *mlxsw_sp, u16 rif_index)
+{
+	u32 adj_discard_index = mlxsw_sp->router->adj_discard_index;
+	enum mlxsw_reg_ratr_trap_action trap_action;
+	char ratr_pl[MLXSW_REG_RATR_LEN];
+
+	trap_action = MLXSW_REG_RATR_TRAP_ACTION_DISCARD_ERRORS;
+	mlxsw_reg_ratr_pack(ratr_pl, MLXSW_REG_RATR_OP_WRITE_WRITE_ENTRY, true,
+			    MLXSW_REG_RATR_TYPE_ETHERNET, adj_discard_index,
+			    rif_index);
+	mlxsw_reg_ratr_trap_action_set(ratr_pl, trap_action);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(ratr), ratr_pl);
+}
+
 static int mlxsw_sp_fib_entry_op_remote(struct mlxsw_sp *mlxsw_sp,
 					struct mlxsw_sp_fib_entry *fib_entry,
 					enum mlxsw_reg_ralue_op op)
 {
+	struct mlxsw_sp_nexthop_group *nh_group = fib_entry->nh_group;
 	char ralue_pl[MLXSW_REG_RALUE_LEN];
 	enum mlxsw_reg_ralue_trap_action trap_action;
 	u16 trap_id = 0;
 	u32 adjacency_index = 0;
 	u16 ecmp_size = 0;
+	int err;
 
 	/* In case the nexthop group adjacency index is valid, use it
 	 * with provided ECMP size. Otherwise, setup trap and pass
@@ -4215,6 +4232,15 @@ static int mlxsw_sp_fib_entry_op_remote(struct mlxsw_sp *mlxsw_sp,
 		trap_action = MLXSW_REG_RALUE_TRAP_ACTION_NOP;
 		adjacency_index = fib_entry->nh_group->adj_index;
 		ecmp_size = fib_entry->nh_group->ecmp_size;
+	} else if (!nh_group->adj_index_valid && nh_group->count &&
+		   nh_group->nh_rif) {
+		err = mlxsw_sp_adj_discard_write(mlxsw_sp,
+						 nh_group->nh_rif->rif_index);
+		if (err)
+			return err;
+		trap_action = MLXSW_REG_RALUE_TRAP_ACTION_NOP;
+		adjacency_index = mlxsw_sp->router->adj_discard_index;
+		ecmp_size = 1;
 	} else {
 		trap_action = MLXSW_REG_RALUE_TRAP_ACTION_TRAP;
 		trap_id = MLXSW_TRAP_ID_RTR_INGRESS0;
@@ -8144,6 +8170,11 @@ int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp,
 	if (err)
 		goto err_neigh_init;
 
+	err = mlxsw_sp_kvdl_alloc(mlxsw_sp, MLXSW_SP_KVDL_ENTRY_TYPE_ADJ, 1,
+				  &router->adj_discard_index);
+	if (err)
+		goto err_adj_discard_index_alloc;
+
 	mlxsw_sp->router->netevent_nb.notifier_call =
 		mlxsw_sp_router_netevent_event;
 	err = register_netevent_notifier(&mlxsw_sp->router->netevent_nb);
@@ -8172,6 +8203,9 @@ int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp,
 err_mp_hash_init:
 	unregister_netevent_notifier(&mlxsw_sp->router->netevent_nb);
 err_register_netevent_notifier:
+	mlxsw_sp_kvdl_free(mlxsw_sp, MLXSW_SP_KVDL_ENTRY_TYPE_ADJ, 1,
+			   router->adj_discard_index);
+err_adj_discard_index_alloc:
 	mlxsw_sp_neigh_fini(mlxsw_sp);
 err_neigh_init:
 	mlxsw_sp_vrs_fini(mlxsw_sp);
@@ -8203,6 +8237,8 @@ void mlxsw_sp_router_fini(struct mlxsw_sp *mlxsw_sp)
 	unregister_fib_notifier(mlxsw_sp_net(mlxsw_sp),
 				&mlxsw_sp->router->fib_nb);
 	unregister_netevent_notifier(&mlxsw_sp->router->netevent_nb);
+	mlxsw_sp_kvdl_free(mlxsw_sp, MLXSW_SP_KVDL_ENTRY_TYPE_ADJ, 1,
+			   mlxsw_sp->router->adj_discard_index);
 	mlxsw_sp_neigh_fini(mlxsw_sp);
 	mlxsw_sp_vrs_fini(mlxsw_sp);
 	mlxsw_sp_mr_fini(mlxsw_sp);

drivers/net/ethernet/mellanox/mlxsw/trap.h

@@ -68,6 +68,7 @@ enum {
 	MLXSW_TRAP_ID_ROUTER_ALERT_IPV4 = 0xD6,
 	MLXSW_TRAP_ID_ROUTER_ALERT_IPV6 = 0xD7,
 	MLXSW_TRAP_ID_DISCARD_ROUTER2 = 0x130,
+	MLXSW_TRAP_ID_DISCARD_ROUTER3 = 0x131,
 	MLXSW_TRAP_ID_DISCARD_ING_PACKET_SMAC_MC = 0x140,
 	MLXSW_TRAP_ID_DISCARD_ING_SWITCH_VTAG_ALLOW = 0x148,
 	MLXSW_TRAP_ID_DISCARD_ING_SWITCH_VLAN = 0x149,