From: Ido Schimmel <idosch@mellanox.com>
Date: Sun, 22 Oct 2017 23:11:48 +0200
Subject: mlxsw: spectrum_router: Populate adjacency entries according to
 weights
Patch-mainline: v4.15-rc1
Git-commit: eb789980d0aa6cd2ebee3eb07792800bbe134bc0
References: bsc#1112374

Up until now the driver assumed all the nexthops have an equal weight
and wrote each to a single adjacency entry.

This patch takes the `weight` parameter into account and populates the
adjacency group according to the relative weight of each nexthop.

Specifically, the weights of all the nexthops that should be offloaded
are first normalized and then used to calculate the upper adjacency
index of each nexthop. This is done according to the hash-threshold
algorithm used by the kernel for IPv4 multi-path routing.

Adjacency groups are currently limited to 32 entries which limits the
weights that can be used, but follow-up patches will introduce groups of
512 entries.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c |  111 ++++++++++++++++--
 1 file changed, 99 insertions(+), 12 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -46,6 +46,7 @@
 #include <linux/if_bridge.h>
 #include <linux/socket.h>
 #include <linux/route.h>
+#include <linux/gcd.h>
 #include <net/netevent.h>
 #include <net/neighbour.h>
 #include <net/arp.h>
@@ -2204,6 +2205,8 @@ struct mlxsw_sp_nexthop {
 	unsigned char gw_addr[sizeof(struct in6_addr)];
 	int ifindex;
 	int nh_weight;
+	int norm_nh_weight;
+	int num_adj_entries;
 	struct mlxsw_sp_rif *rif;
 	u8 should_offload:1, /* set indicates this neigh is connected and
 			      * should be put to KVD linear area of this group.
@@ -2233,6 +2236,7 @@ struct mlxsw_sp_nexthop_group {
 	u32 adj_index;
 	u16 ecmp_size;
 	u16 count;
+	int sum_norm_weight;
 	struct mlxsw_sp_nexthop nexthops[0];
 #define nh_rif	nexthops[0].rif
 };
@@ -2318,7 +2322,7 @@ int mlxsw_sp_nexthop_indexes(struct mlxs
 		if (nh_iter == nh)
 			break;
 		if (nh_iter->offloaded)
-			adj_hash_index++;
+			adj_hash_index += nh_iter->num_adj_entries;
 	}
 
 	*p_adj_hash_index = adj_hash_index;
@@ -2601,8 +2605,8 @@ static int mlxsw_sp_adj_index_mass_updat
 	return 0;
 }
 
-int mlxsw_sp_nexthop_update(struct mlxsw_sp *mlxsw_sp, u32 adj_index,
-			    struct mlxsw_sp_nexthop *nh)
+static int __mlxsw_sp_nexthop_update(struct mlxsw_sp *mlxsw_sp, u32 adj_index,
+				     struct mlxsw_sp_nexthop *nh)
 {
 	struct mlxsw_sp_neigh_entry *neigh_entry = nh->neigh_entry;
 	char ratr_pl[MLXSW_REG_RATR_LEN];
@@ -2619,9 +2623,25 @@ int mlxsw_sp_nexthop_update(struct mlxsw
 	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(ratr), ratr_pl);
 }
 
-static int mlxsw_sp_nexthop_ipip_update(struct mlxsw_sp *mlxsw_sp,
-					u32 adj_index,
-					struct mlxsw_sp_nexthop *nh)
+int mlxsw_sp_nexthop_update(struct mlxsw_sp *mlxsw_sp, u32 adj_index,
+			    struct mlxsw_sp_nexthop *nh)
+{
+	int i;
+
+	for (i = 0; i < nh->num_adj_entries; i++) {
+		int err;
+
+		err = __mlxsw_sp_nexthop_update(mlxsw_sp, adj_index + i, nh);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int __mlxsw_sp_nexthop_ipip_update(struct mlxsw_sp *mlxsw_sp,
+					  u32 adj_index,
+					  struct mlxsw_sp_nexthop *nh)
 {
 	const struct mlxsw_sp_ipip_ops *ipip_ops;
 
@@ -2629,6 +2649,24 @@ static int mlxsw_sp_nexthop_ipip_update(
 	return ipip_ops->nexthop_update(mlxsw_sp, adj_index, nh->ipip_entry);
 }
 
+static int mlxsw_sp_nexthop_ipip_update(struct mlxsw_sp *mlxsw_sp,
+					u32 adj_index,
+					struct mlxsw_sp_nexthop *nh)
+{
+	int i;
+
+	for (i = 0; i < nh->num_adj_entries; i++) {
+		int err;
+
+		err = __mlxsw_sp_nexthop_ipip_update(mlxsw_sp, adj_index + i,
+						     nh);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static int
 mlxsw_sp_nexthop_group_update(struct mlxsw_sp *mlxsw_sp,
 			      struct mlxsw_sp_nexthop_group *nh_grp,
@@ -2663,7 +2701,7 @@ mlxsw_sp_nexthop_group_update(struct mlx
 			nh->update = 0;
 			nh->offloaded = 1;
 		}
-		adj_index++;
+		adj_index += nh->num_adj_entries;
 	}
 	return 0;
 }
@@ -2762,16 +2800,64 @@ static int mlxsw_sp_fix_adj_grp_size(str
 }
 
 static void
+mlxsw_sp_nexthop_group_normalize(struct mlxsw_sp_nexthop_group *nh_grp)
+{
+	int i, g = 0, sum_norm_weight = 0;
+	struct mlxsw_sp_nexthop *nh;
+
+	for (i = 0; i < nh_grp->count; i++) {
+		nh = &nh_grp->nexthops[i];
+
+		if (!nh->should_offload)
+			continue;
+		if (g > 0)
+			g = gcd(nh->nh_weight, g);
+		else
+			g = nh->nh_weight;
+	}
+
+	for (i = 0; i < nh_grp->count; i++) {
+		nh = &nh_grp->nexthops[i];
+
+		if (!nh->should_offload)
+			continue;
+		nh->norm_nh_weight = nh->nh_weight / g;
+		sum_norm_weight += nh->norm_nh_weight;
+	}
+
+	nh_grp->sum_norm_weight = sum_norm_weight;
+}
+
+static void
+mlxsw_sp_nexthop_group_rebalance(struct mlxsw_sp_nexthop_group *nh_grp)
+{
+	int total = nh_grp->sum_norm_weight;
+	u16 ecmp_size = nh_grp->ecmp_size;
+	int i, weight = 0, lower_bound = 0;
+
+	for (i = 0; i < nh_grp->count; i++) {
+		struct mlxsw_sp_nexthop *nh = &nh_grp->nexthops[i];
+		int upper_bound;
+
+		if (!nh->should_offload)
+			continue;
+		weight += nh->norm_nh_weight;
+		upper_bound = DIV_ROUND_CLOSEST(ecmp_size * weight, total);
+		nh->num_adj_entries = upper_bound - lower_bound;
+		lower_bound = upper_bound;
+	}
+}
+
+static void
 mlxsw_sp_nexthop_group_refresh(struct mlxsw_sp *mlxsw_sp,
 			       struct mlxsw_sp_nexthop_group *nh_grp)
 {
+	u16 ecmp_size, old_ecmp_size;
 	struct mlxsw_sp_nexthop *nh;
 	bool offload_change = false;
 	u32 adj_index;
-	u16 ecmp_size = 0;
 	bool old_adj_index_valid;
 	u32 old_adj_index;
-	u16 old_ecmp_size;
 	int i;
 	int err;
 
@@ -2788,8 +2874,6 @@ mlxsw_sp_nexthop_group_refresh(struct ml
 			if (nh->should_offload)
 				nh->update = 1;
 		}
-		if (nh->should_offload)
-			ecmp_size++;
 	}
 	if (!offload_change) {
 		/* Nothing was added or removed, so no need to reallocate. Just
@@ -2802,12 +2886,14 @@ mlxsw_sp_nexthop_group_refresh(struct ml
 		}
 		return;
 	}
-	if (!ecmp_size)
+	mlxsw_sp_nexthop_group_normalize(nh_grp);
+	if (!nh_grp->sum_norm_weight)
 		/* No neigh of this group is connected so we just set
 		 * the trap and let everthing flow through kernel.
 		 */
 		goto set_trap;
 
+	ecmp_size = nh_grp->sum_norm_weight;
 	err = mlxsw_sp_fix_adj_grp_size(mlxsw_sp, &ecmp_size);
 	if (err)
 		/* No valid allocation size available. */
@@ -2827,6 +2913,7 @@ mlxsw_sp_nexthop_group_refresh(struct ml
 	nh_grp->adj_index_valid = 1;
 	nh_grp->adj_index = adj_index;
 	nh_grp->ecmp_size = ecmp_size;
+	mlxsw_sp_nexthop_group_rebalance(nh_grp);
 	err = mlxsw_sp_nexthop_group_update(mlxsw_sp, nh_grp, true);
 	if (err) {
 		dev_warn(mlxsw_sp->bus_info->dev, "Failed to update neigh MAC in adjacency table.\n");