mlxsw: spectrum_router: Add support for blackhole nexthops

Add support for blackhole nexthops by programming them to the adjacency
table with a discard action.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -913,7 +913,8 @@ static u64 mlxsw_sp_dpipe_table_adj_size(struct mlxsw_sp *mlxsw_sp)
 
 	mlxsw_sp_nexthop_for_each(nh, mlxsw_sp->router)
 		if (mlxsw_sp_nexthop_offload(nh) &&
-		    !mlxsw_sp_nexthop_group_has_ipip(nh))
+		    !mlxsw_sp_nexthop_group_has_ipip(nh) &&
+		    !mlxsw_sp_nexthop_is_discard(nh))
 			size++;
 	return size;
 }
@@ -1105,7 +1106,8 @@ mlxsw_sp_dpipe_table_adj_entries_get(struct mlxsw_sp *mlxsw_sp,
 	nh_count = 0;
 	mlxsw_sp_nexthop_for_each(nh, mlxsw_sp->router) {
 		if (!mlxsw_sp_nexthop_offload(nh) ||
-		    mlxsw_sp_nexthop_group_has_ipip(nh))
+		    mlxsw_sp_nexthop_group_has_ipip(nh) ||
+		    mlxsw_sp_nexthop_is_discard(nh))
 			continue;
 
 		if (nh_count < nh_skip)
@@ -1186,7 +1188,8 @@ static int mlxsw_sp_dpipe_table_adj_counters_update(void *priv, bool enable)
 
 	mlxsw_sp_nexthop_for_each(nh, mlxsw_sp->router) {
 		if (!mlxsw_sp_nexthop_offload(nh) ||
-		    mlxsw_sp_nexthop_group_has_ipip(nh))
+		    mlxsw_sp_nexthop_group_has_ipip(nh) ||
+		    mlxsw_sp_nexthop_is_discard(nh))
 			continue;
 
 		mlxsw_sp_nexthop_indexes(nh, &adj_index, &adj_size,

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

@@ -2858,9 +2858,10 @@ struct mlxsw_sp_nexthop {
 	   offloaded:1, /* set in case the neigh is actually put into
 			 * KVD linear area of this group.
 			 */
-	   update:1; /* set indicates that MAC of this neigh should be
+	   update:1, /* set indicates that MAC of this neigh should be
 		      * updated in HW
 		      */
+	   discard:1; /* nexthop is programmed to discard packets */
 	enum mlxsw_sp_nexthop_type type;
 	union {
 		struct mlxsw_sp_neigh_entry *neigh_entry;
@@ -3011,6 +3012,11 @@ bool mlxsw_sp_nexthop_group_has_ipip(struct mlxsw_sp_nexthop *nh)
 	return false;
 }
 
+bool mlxsw_sp_nexthop_is_discard(const struct mlxsw_sp_nexthop *nh)
+{
+	return nh->discard;
+}
+
 struct mlxsw_sp_nexthop_group_cmp_arg {
 	enum mlxsw_sp_nexthop_group_type type;
 	union {
@@ -3285,7 +3291,11 @@ static int __mlxsw_sp_nexthop_update(struct mlxsw_sp *mlxsw_sp, u32 adj_index,
 	mlxsw_reg_ratr_pack(ratr_pl, MLXSW_REG_RATR_OP_WRITE_WRITE_ENTRY,
 			    true, MLXSW_REG_RATR_TYPE_ETHERNET,
 			    adj_index, nh->rif->rif_index);
-	mlxsw_reg_ratr_eth_entry_pack(ratr_pl, neigh_entry->ha);
+	if (nh->discard)
+		mlxsw_reg_ratr_trap_action_set(ratr_pl,
+					       MLXSW_REG_RATR_TRAP_ACTION_DISCARD_ERRORS);
+	else
+		mlxsw_reg_ratr_eth_entry_pack(ratr_pl, neigh_entry->ha);
 	if (nh->counter_valid)
 		mlxsw_reg_ratr_counter_pack(ratr_pl, nh->counter_index, true);
 	else
@@ -4128,9 +4138,7 @@ mlxsw_sp_nexthop_obj_single_validate(struct mlxsw_sp *mlxsw_sp,
 {
 	int err = -EINVAL;
 
-	if (nh->is_reject)
-		NL_SET_ERR_MSG_MOD(extack, "Blackhole nexthops are not supported");
-	else if (nh->is_fdb)
+	if (nh->is_fdb)
 		NL_SET_ERR_MSG_MOD(extack, "FDB nexthops are not supported");
 	else if (nh->has_encap)
 		NL_SET_ERR_MSG_MOD(extack, "Encapsulating nexthops are not supported");
@@ -4165,7 +4173,7 @@ mlxsw_sp_nexthop_obj_group_validate(struct mlxsw_sp *mlxsw_sp,
 		/* Device only nexthops with an IPIP device are programmed as
 		 * encapsulating adjacency entries.
 		 */
-		if (!nh->gw_family &&
+		if (!nh->gw_family && !nh->is_reject &&
 		    !mlxsw_sp_netdev_ipip_type(mlxsw_sp, nh->dev, NULL)) {
 			NL_SET_ERR_MSG_MOD(extack, "Nexthop group entry does not have a gateway");
 			return -EINVAL;
@@ -4199,10 +4207,31 @@ static bool mlxsw_sp_nexthop_obj_is_gateway(struct mlxsw_sp *mlxsw_sp,
 		return true;
 
 	dev = info->nh->dev;
-	return info->nh->gw_family ||
+	return info->nh->gw_family || info->nh->is_reject ||
 	       mlxsw_sp_netdev_ipip_type(mlxsw_sp, dev, NULL);
 }
 
+static void mlxsw_sp_nexthop_obj_blackhole_init(struct mlxsw_sp *mlxsw_sp,
+						struct mlxsw_sp_nexthop *nh)
+{
+	u16 lb_rif_index = mlxsw_sp->router->lb_rif_index;
+
+	nh->discard = 1;
+	nh->should_offload = 1;
+	/* While nexthops that discard packets do not forward packets
+	 * via an egress RIF, they still need to be programmed using a
+	 * valid RIF, so use the loopback RIF created during init.
+	 */
+	nh->rif = mlxsw_sp->router->rifs[lb_rif_index];
+}
+
+static void mlxsw_sp_nexthop_obj_blackhole_fini(struct mlxsw_sp *mlxsw_sp,
+						struct mlxsw_sp_nexthop *nh)
+{
+	nh->rif = NULL;
+	nh->should_offload = 0;
+}
+
 static int
 mlxsw_sp_nexthop_obj_init(struct mlxsw_sp *mlxsw_sp,
 			  struct mlxsw_sp_nexthop_group *nh_grp,
@@ -4236,6 +4265,9 @@ mlxsw_sp_nexthop_obj_init(struct mlxsw_sp *mlxsw_sp,
 	if (err)
 		goto err_type_init;
 
+	if (nh_obj->is_reject)
+		mlxsw_sp_nexthop_obj_blackhole_init(mlxsw_sp, nh);
+
 	return 0;
 
 err_type_init:
@@ -4247,6 +4279,8 @@ mlxsw_sp_nexthop_obj_init(struct mlxsw_sp *mlxsw_sp,
 static void mlxsw_sp_nexthop_obj_fini(struct mlxsw_sp *mlxsw_sp,
 				      struct mlxsw_sp_nexthop *nh)
 {
+	if (nh->discard)
+		mlxsw_sp_nexthop_obj_blackhole_fini(mlxsw_sp, nh);
 	mlxsw_sp_nexthop_type_fini(mlxsw_sp, nh);
 	list_del(&nh->router_list_node);
 	mlxsw_sp_nexthop_counter_free(mlxsw_sp, nh);

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

@@ -201,6 +201,7 @@ int mlxsw_sp_nexthop_indexes(struct mlxsw_sp_nexthop *nh, u32 *p_adj_index,
 			     u32 *p_adj_size, u32 *p_adj_hash_index);
 struct mlxsw_sp_rif *mlxsw_sp_nexthop_rif(struct mlxsw_sp_nexthop *nh);
 bool mlxsw_sp_nexthop_group_has_ipip(struct mlxsw_sp_nexthop *nh);
+bool mlxsw_sp_nexthop_is_discard(const struct mlxsw_sp_nexthop *nh);
 #define mlxsw_sp_nexthop_for_each(nh, router)				\
 	for (nh = mlxsw_sp_nexthop_next(router, NULL); nh;		\
 	     nh = mlxsw_sp_nexthop_next(router, nh))