mlxsw: spectrum_router: Align multipath hash parameters with kernel's

Up until now we used the hardware's defaults for multipath hash
computation. This patch aligns the hardware's multipath parameters with
the kernel's.

For IPv4 packets, the parameters are determined according to the
'fib_multipath_hash_policy' sysctl during module initialization. In case
L3-mode is requested, only the source and destination IP addresses are
used. There is no special handling of ICMP error packets.

In case L4-mode is requested, a 5-tuple is used: source and destination
IP addresses, source and destination ports and IP protocol. Note that
the layer 4 fields are not considered for fragmented packets.

For IPv6 packets, the source and destination IP addresses are used, as
well as the flow label and the next header fields.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -47,6 +47,7 @@
 #include <linux/socket.h>
 #include <linux/route.h>
 #include <linux/gcd.h>
+#include <linux/random.h>
 #include <net/netevent.h>
 #include <net/neighbour.h>
 #include <net/arp.h>
@@ -6644,6 +6645,64 @@ static void mlxsw_sp_router_fib_dump_flush(struct notifier_block *nb)
 	mlxsw_sp_router_fib_flush(router->mlxsw_sp);
 }
 
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+static void mlxsw_sp_mp_hash_header_set(char *recr2_pl, int header)
+{
+	mlxsw_reg_recr2_outer_header_enables_set(recr2_pl, header, true);
+}
+
+static void mlxsw_sp_mp_hash_field_set(char *recr2_pl, int field)
+{
+	mlxsw_reg_recr2_outer_header_fields_enable_set(recr2_pl, field, true);
+}
+
+static void mlxsw_sp_mp4_hash_init(char *recr2_pl)
+{
+	bool only_l3 = !init_net.ipv4.sysctl_fib_multipath_hash_policy;
+
+	mlxsw_sp_mp_hash_header_set(recr2_pl,
+				    MLXSW_REG_RECR2_IPV4_EN_NOT_TCP_NOT_UDP);
+	mlxsw_sp_mp_hash_header_set(recr2_pl, MLXSW_REG_RECR2_IPV4_EN_TCP_UDP);
+	mlxsw_reg_recr2_ipv4_sip_enable(recr2_pl);
+	mlxsw_reg_recr2_ipv4_dip_enable(recr2_pl);
+	if (only_l3)
+		return;
+	mlxsw_sp_mp_hash_header_set(recr2_pl, MLXSW_REG_RECR2_TCP_UDP_EN_IPV4);
+	mlxsw_sp_mp_hash_field_set(recr2_pl, MLXSW_REG_RECR2_IPV4_PROTOCOL);
+	mlxsw_sp_mp_hash_field_set(recr2_pl, MLXSW_REG_RECR2_TCP_UDP_SPORT);
+	mlxsw_sp_mp_hash_field_set(recr2_pl, MLXSW_REG_RECR2_TCP_UDP_DPORT);
+}
+
+static void mlxsw_sp_mp6_hash_init(char *recr2_pl)
+{
+	mlxsw_sp_mp_hash_header_set(recr2_pl,
+				    MLXSW_REG_RECR2_IPV6_EN_NOT_TCP_NOT_UDP);
+	mlxsw_sp_mp_hash_header_set(recr2_pl, MLXSW_REG_RECR2_IPV6_EN_TCP_UDP);
+	mlxsw_reg_recr2_ipv6_sip_enable(recr2_pl);
+	mlxsw_reg_recr2_ipv6_dip_enable(recr2_pl);
+	mlxsw_sp_mp_hash_field_set(recr2_pl, MLXSW_REG_RECR2_IPV6_FLOW_LABEL);
+	mlxsw_sp_mp_hash_field_set(recr2_pl, MLXSW_REG_RECR2_IPV6_NEXT_HEADER);
+}
+
+static int mlxsw_sp_mp_hash_init(struct mlxsw_sp *mlxsw_sp)
+{
+	char recr2_pl[MLXSW_REG_RECR2_LEN];
+	u32 seed;
+
+	get_random_bytes(&seed, sizeof(seed));
+	mlxsw_reg_recr2_pack(recr2_pl, seed);
+	mlxsw_sp_mp4_hash_init(recr2_pl);
+	mlxsw_sp_mp6_hash_init(recr2_pl);
+
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(recr2), recr2_pl);
+}
+#else
+static int mlxsw_sp_mp_hash_init(struct mlxsw_sp *mlxsw_sp)
+{
+	return 0;
+}
+#endif
+
 static int __mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 {
 	char rgcr_pl[MLXSW_REG_RGCR_LEN];
@@ -6727,6 +6786,10 @@ int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 	if (err)
 		goto err_register_netevent_notifier;
 
+	err = mlxsw_sp_mp_hash_init(mlxsw_sp);
+	if (err)
+		goto err_mp_hash_init;
+
 	mlxsw_sp->router->fib_nb.notifier_call = mlxsw_sp_router_fib_event;
 	err = register_fib_notifier(&mlxsw_sp->router->fib_nb,
 				    mlxsw_sp_router_fib_dump_flush);
@@ -6736,6 +6799,7 @@ int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 	return 0;
 
 err_register_fib_notifier:
+err_mp_hash_init:
 	unregister_netevent_notifier(&mlxsw_sp->router->netevent_nb);
 err_register_netevent_notifier:
 	mlxsw_sp_neigh_fini(mlxsw_sp);