mlxsw: spectrum_router: Support IPv4 underlay decap

Unlike encapsulation, which is represented by a next hop forwarding to
an IPIP tunnel, decapsulation is a type of local route. It is created
for local routes whose prefix corresponds to the local address of one of
offloaded IPIP tunnels. When the tunnel is removed (i.e. all the encap
next hops are removed), the decap offload is migrated back to a trap for
resolution in slow path.

This patch assumes that decap route is already present when encap route
is added. A follow-up patch will fix this issue.

Note that this patch only supports IPv4 underlay. Support for IPv6
underlay will be subject to follow-up work apart from this patchset.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: pmachata

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

@@ -36,6 +36,7 @@
 #define _MLXSW_IPIP_H_
 
 #include "spectrum_router.h"
+#include <net/ip_fib.h>
 
 enum mlxsw_sp_ipip_type {
 	MLXSW_SP_IPIP_TYPE_MAX,
@@ -46,6 +47,7 @@ struct mlxsw_sp_ipip_entry {
 	struct net_device *ol_dev; /* Overlay. */
 	struct mlxsw_sp_rif_ipip_lb *ol_lb;
 	unsigned int ref_count; /* Number of next hops using the tunnel. */
+	struct mlxsw_sp_fib_entry *decap_fib_entry;
 	struct list_head ipip_list_node;
 };
 
@@ -64,6 +66,11 @@ struct mlxsw_sp_ipip_ops {
 	struct mlxsw_sp_rif_ipip_lb_config
 	(*ol_loopback_config)(struct mlxsw_sp *mlxsw_sp,
 			      const struct net_device *ol_dev);
+
+	int (*fib_entry_op)(struct mlxsw_sp *mlxsw_sp,
+			    struct mlxsw_sp_ipip_entry *ipip_entry,
+			    enum mlxsw_reg_ralue_op op,
+			    u32 tunnel_index);
 };
 
 extern const struct mlxsw_sp_ipip_ops *mlxsw_sp_ipip_ops_arr[];

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

@@ -381,6 +381,14 @@ enum mlxsw_sp_fib_entry_type {
 	MLXSW_SP_FIB_ENTRY_TYPE_REMOTE,
 	MLXSW_SP_FIB_ENTRY_TYPE_LOCAL,
 	MLXSW_SP_FIB_ENTRY_TYPE_TRAP,
+
+	/* This is a special case of local delivery, where a packet should be
+	 * decapsulated on reception. Note that there is no corresponding ENCAP,
+	 * because that's a type of next hop, not of FIB entry. (There can be
+	 * several next hops in a REMOTE entry, and some of them may be
+	 * encapsulating entries.)
+	 */
+	MLXSW_SP_FIB_ENTRY_TYPE_IPIP_DECAP,
 };
 
 struct mlxsw_sp_nexthop_group;
@@ -394,12 +402,18 @@ struct mlxsw_sp_fib_node {
 	struct mlxsw_sp_fib_key key;
 };
 
+struct mlxsw_sp_fib_entry_decap {
+	struct mlxsw_sp_ipip_entry *ipip_entry;
+	u32 tunnel_index;
+};
+
 struct mlxsw_sp_fib_entry {
 	struct list_head list;
 	struct mlxsw_sp_fib_node *fib_node;
 	enum mlxsw_sp_fib_entry_type type;
 	struct list_head nexthop_group_node;
 	struct mlxsw_sp_nexthop_group *nh_group;
+	struct mlxsw_sp_fib_entry_decap decap; /* Valid for decap entries. */
 };
 
 struct mlxsw_sp_fib4_entry {
@@ -1031,6 +1045,48 @@ mlxsw_sp_ipip_entry_saddr_matches(struct mlxsw_sp *mlxsw_sp,
 	       mlxsw_sp_l3addr_eq(&tun_saddr, &saddr);
 }
 
+static int
+mlxsw_sp_fib_entry_decap_init(struct mlxsw_sp *mlxsw_sp,
+			      struct mlxsw_sp_fib_entry *fib_entry,
+			      struct mlxsw_sp_ipip_entry *ipip_entry)
+{
+	u32 tunnel_index;
+	int err;
+
+	err = mlxsw_sp_kvdl_alloc(mlxsw_sp, 1, &tunnel_index);
+	if (err)
+		return err;
+
+	ipip_entry->decap_fib_entry = fib_entry;
+	fib_entry->decap.ipip_entry = ipip_entry;
+	fib_entry->decap.tunnel_index = tunnel_index;
+	return 0;
+}
+
+static void mlxsw_sp_fib_entry_decap_fini(struct mlxsw_sp *mlxsw_sp,
+					  struct mlxsw_sp_fib_entry *fib_entry)
+{
+	/* Unlink this node from the IPIP entry that it's the decap entry of. */
+	fib_entry->decap.ipip_entry->decap_fib_entry = NULL;
+	fib_entry->decap.ipip_entry = NULL;
+	mlxsw_sp_kvdl_free(mlxsw_sp, fib_entry->decap.tunnel_index);
+}
+
+static int mlxsw_sp_fib_entry_update(struct mlxsw_sp *mlxsw_sp,
+				     struct mlxsw_sp_fib_entry *fib_entry);
+
+static void
+mlxsw_sp_ipip_entry_demote_decap(struct mlxsw_sp *mlxsw_sp,
+				 struct mlxsw_sp_ipip_entry *ipip_entry)
+{
+	struct mlxsw_sp_fib_entry *fib_entry = ipip_entry->decap_fib_entry;
+
+	mlxsw_sp_fib_entry_decap_fini(mlxsw_sp, fib_entry);
+	fib_entry->type = MLXSW_SP_FIB_ENTRY_TYPE_TRAP;
+
+	mlxsw_sp_fib_entry_update(mlxsw_sp, fib_entry);
+}
+
 static struct mlxsw_sp_ipip_entry *
 mlxsw_sp_ipip_entry_get(struct mlxsw_sp *mlxsw_sp,
 			enum mlxsw_sp_ipip_type ipipt,
@@ -1076,10 +1132,51 @@ mlxsw_sp_ipip_entry_put(struct mlxsw_sp *mlxsw_sp,
 {
 	if (--ipip_entry->ref_count == 0) {
 		list_del(&ipip_entry->ipip_list_node);
+		if (ipip_entry->decap_fib_entry)
+			mlxsw_sp_ipip_entry_demote_decap(mlxsw_sp, ipip_entry);
 		mlxsw_sp_ipip_entry_destroy(ipip_entry);
 	}
 }
 
+static bool
+mlxsw_sp_ipip_entry_matches_decap(struct mlxsw_sp *mlxsw_sp,
+				  const struct net_device *ul_dev,
+				  enum mlxsw_sp_l3proto ul_proto,
+				  union mlxsw_sp_l3addr ul_dip,
+				  struct mlxsw_sp_ipip_entry *ipip_entry)
+{
+	u32 ul_tb_id = l3mdev_fib_table(ul_dev) ? : RT_TABLE_MAIN;
+	enum mlxsw_sp_ipip_type ipipt = ipip_entry->ipipt;
+	struct net_device *ipip_ul_dev;
+
+	if (mlxsw_sp->router->ipip_ops_arr[ipipt]->ul_proto != ul_proto)
+		return false;
+
+	ipip_ul_dev = __mlxsw_sp_ipip_netdev_ul_dev_get(ipip_entry->ol_dev);
+	return mlxsw_sp_ipip_entry_saddr_matches(mlxsw_sp, ul_proto, ul_dip,
+						 ul_tb_id, ipip_entry) &&
+	       (!ipip_ul_dev || ipip_ul_dev == ul_dev);
+}
+
+/* Given decap parameters, find the corresponding IPIP entry. */
+static struct mlxsw_sp_ipip_entry *
+mlxsw_sp_ipip_entry_find_by_decap(struct mlxsw_sp *mlxsw_sp,
+				  const struct net_device *ul_dev,
+				  enum mlxsw_sp_l3proto ul_proto,
+				  union mlxsw_sp_l3addr ul_dip)
+{
+	struct mlxsw_sp_ipip_entry *ipip_entry;
+
+	list_for_each_entry(ipip_entry, &mlxsw_sp->router->ipip_list,
+			    ipip_list_node)
+		if (mlxsw_sp_ipip_entry_matches_decap(mlxsw_sp, ul_dev,
+						      ul_proto, ul_dip,
+						      ipip_entry))
+			return ipip_entry;
+
+	return NULL;
+}
+
 struct mlxsw_sp_neigh_key {
 	struct neighbour *n;
 };
@@ -2186,9 +2283,6 @@ mlxsw_sp_nexthop_group_update(struct mlxsw_sp *mlxsw_sp,
 	return 0;
 }
 
-static int mlxsw_sp_fib_entry_update(struct mlxsw_sp *mlxsw_sp,
-				     struct mlxsw_sp_fib_entry *fib_entry);
-
 static bool
 mlxsw_sp_fib_node_entry_is_first(const struct mlxsw_sp_fib_node *fib_node,
 				 const struct mlxsw_sp_fib_entry *fib_entry);
@@ -2779,6 +2873,8 @@ mlxsw_sp_fib_entry_should_offload(const struct mlxsw_sp_fib_entry *fib_entry)
 		return !!nh_group->adj_index_valid;
 	case MLXSW_SP_FIB_ENTRY_TYPE_LOCAL:
 		return !!nh_group->nh_rif;
+	case MLXSW_SP_FIB_ENTRY_TYPE_IPIP_DECAP:
+		return true;
 	default:
 		return false;
 	}
@@ -2810,7 +2906,8 @@ mlxsw_sp_fib4_entry_offload_set(struct mlxsw_sp_fib_entry *fib_entry)
 	struct mlxsw_sp_nexthop_group *nh_grp = fib_entry->nh_group;
 	int i;
 
-	if (fib_entry->type == MLXSW_SP_FIB_ENTRY_TYPE_LOCAL) {
+	if (fib_entry->type == MLXSW_SP_FIB_ENTRY_TYPE_LOCAL ||
+	    fib_entry->type == MLXSW_SP_FIB_ENTRY_TYPE_IPIP_DECAP) {
 		nh_grp->nexthops->key.fib_nh->nh_flags |= RTNH_F_OFFLOAD;
 		return;
 	}
@@ -3015,6 +3112,22 @@ static int mlxsw_sp_fib_entry_op_trap(struct mlxsw_sp *mlxsw_sp,
 	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(ralue), ralue_pl);
 }
 
+static int
+mlxsw_sp_fib_entry_op_ipip_decap(struct mlxsw_sp *mlxsw_sp,
+				 struct mlxsw_sp_fib_entry *fib_entry,
+				 enum mlxsw_reg_ralue_op op)
+{
+	struct mlxsw_sp_ipip_entry *ipip_entry = fib_entry->decap.ipip_entry;
+	const struct mlxsw_sp_ipip_ops *ipip_ops;
+
+	if (WARN_ON(!ipip_entry))
+		return -EINVAL;
+
+	ipip_ops = mlxsw_sp->router->ipip_ops_arr[ipip_entry->ipipt];
+	return ipip_ops->fib_entry_op(mlxsw_sp, ipip_entry, op,
+				      fib_entry->decap.tunnel_index);
+}
+
 static int __mlxsw_sp_fib_entry_op(struct mlxsw_sp *mlxsw_sp,
 				   struct mlxsw_sp_fib_entry *fib_entry,
 				   enum mlxsw_reg_ralue_op op)
@@ -3026,6 +3139,9 @@ static int __mlxsw_sp_fib_entry_op(struct mlxsw_sp *mlxsw_sp,
 		return mlxsw_sp_fib_entry_op_local(mlxsw_sp, fib_entry, op);
 	case MLXSW_SP_FIB_ENTRY_TYPE_TRAP:
 		return mlxsw_sp_fib_entry_op_trap(mlxsw_sp, fib_entry, op);
+	case MLXSW_SP_FIB_ENTRY_TYPE_IPIP_DECAP:
+		return mlxsw_sp_fib_entry_op_ipip_decap(mlxsw_sp,
+							fib_entry, op);
 	}
 	return -EINVAL;
 }
@@ -3060,11 +3176,23 @@ mlxsw_sp_fib4_entry_type_set(struct mlxsw_sp *mlxsw_sp,
 			     const struct fib_entry_notifier_info *fen_info,
 			     struct mlxsw_sp_fib_entry *fib_entry)
 {
+	union mlxsw_sp_l3addr dip = { .addr4 = htonl(fen_info->dst) };
+	struct net_device *dev = fen_info->fi->fib_dev;
+	struct mlxsw_sp_ipip_entry *ipip_entry;
 	struct fib_info *fi = fen_info->fi;
 
 	switch (fen_info->type) {
-	case RTN_BROADCAST: /* fall through */
 	case RTN_LOCAL:
+		ipip_entry = mlxsw_sp_ipip_entry_find_by_decap(mlxsw_sp, dev,
+						 MLXSW_SP_L3_PROTO_IPV4, dip);
+		if (ipip_entry) {
+			fib_entry->type = MLXSW_SP_FIB_ENTRY_TYPE_IPIP_DECAP;
+			return mlxsw_sp_fib_entry_decap_init(mlxsw_sp,
+							     fib_entry,
+							     ipip_entry);
+		}
+		/* fall through */
+	case RTN_BROADCAST:
 		fib_entry->type = MLXSW_SP_FIB_ENTRY_TYPE_TRAP;
 		return 0;
 	case RTN_UNREACHABLE: /* fall through */
@@ -3557,6 +3685,9 @@ mlxsw_sp_fib4_node_entry_unlink(struct mlxsw_sp *mlxsw_sp,
 {
 	mlxsw_sp_fib_node_entry_del(mlxsw_sp, &fib4_entry->common);
 	mlxsw_sp_fib4_node_list_remove(fib4_entry);
+
+	if (fib4_entry->common.type == MLXSW_SP_FIB_ENTRY_TYPE_IPIP_DECAP)
+		mlxsw_sp_fib_entry_decap_fini(mlxsw_sp, &fib4_entry->common);
 }
 
 static void mlxsw_sp_fib4_entry_replace(struct mlxsw_sp *mlxsw_sp,

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

@@ -97,5 +97,8 @@ mlxsw_sp_neigh_entry_counter_update(struct mlxsw_sp *mlxsw_sp,
 				    struct mlxsw_sp_neigh_entry *neigh_entry,
 				    bool adding);
 bool mlxsw_sp_neigh_ipv6_ignore(struct mlxsw_sp_neigh_entry *neigh_entry);
+union mlxsw_sp_l3addr
+mlxsw_sp_ipip_netdev_saddr(enum mlxsw_sp_l3proto proto,
+			   const struct net_device *ol_dev);
 
 #endif /* _MLXSW_ROUTER_H_*/