net/mlx5: Lag, use buckets in hash mode

When in hardware lag and the NIC has more than 2 ports when one port
goes down need to distribute the traffic between the remaining
active ports.

For better spread in such cases instead of using 1-to-1 mapping and only
4 slots in the hash, use many.

Each port will have many slots that point to it. When a port goes down
go over all the slots that pointed to that port and spread them between
the remaining active ports. Once the port comes back restore the default
mapping.

We will have number_of_ports * MLX5_LAG_MAX_HASH_BUCKETS slots.
Each MLX5_LAG_MAX_HASH_BUCKETS belong to a different port.
The native mapping is such that:

port 1: The first MLX5_LAG_MAX_HASH_BUCKETS slots are: [1, 1, .., 1]
which means if a packet is hased into one of this slots it will hit the
wire via port 1.

port 2: The second MLX5_LAG_MAX_HASH_BUCKETS slots are: [2, 2, .., 2]
which means if a packet is hased into one of this slots it will hit the
wire via port2.

and this mapping is the same of the rest of the ports.
On a failover, lets say port 2 goes down (port 1, 3, 4 are still up).
the new mapping for port 2 will be:

port 2: The second MLX5_LAG_MAX_HASH_BUCKETS are: [1, 3, 1, 4, .., 4]
which means the mapping was changed from the native mapping to a mapping
that consists of only the active ports.

With this if a port goes down the traffic will be split between the
active ports randomly

Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Author: mark-bloch

drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c

@@ -107,14 +107,73 @@ int mlx5_cmd_destroy_vport_lag(struct mlx5_core_dev *dev)
 }
 EXPORT_SYMBOL(mlx5_cmd_destroy_vport_lag);
 
+static void mlx5_infer_tx_disabled(struct lag_tracker *tracker, u8 num_ports,
+				   u8 *ports, int *num_disabled)
+{
+	int i;
+
+	*num_disabled = 0;
+	for (i = 0; i < num_ports; i++) {
+		if (!tracker->netdev_state[i].tx_enabled ||
+		    !tracker->netdev_state[i].link_up)
+			ports[(*num_disabled)++] = i;
+	}
+}
+
+static void mlx5_infer_tx_enabled(struct lag_tracker *tracker, u8 num_ports,
+				  u8 *ports, int *num_enabled)
+{
+	int i;
+
+	*num_enabled = 0;
+	for (i = 0; i < num_ports; i++) {
+		if (tracker->netdev_state[i].tx_enabled &&
+		    tracker->netdev_state[i].link_up)
+			ports[(*num_enabled)++] = i;
+	}
+
+	if (*num_enabled == 0)
+		mlx5_infer_tx_disabled(tracker, num_ports, ports, num_enabled);
+}
+
 static void mlx5_lag_print_mapping(struct mlx5_core_dev *dev,
-				   struct mlx5_lag *ldev)
+				   struct mlx5_lag *ldev,
+				   struct lag_tracker *tracker,
+				   u8 flags)
 {
+	char buf[MLX5_MAX_PORTS * 10 + 1] = {};
+	u8 enabled_ports[MLX5_MAX_PORTS] = {};
+	int written = 0;
+	int num_enabled;
+	int idx;
+	int err;
 	int i;
+	int j;
 
-	mlx5_core_info(dev, "lag map:\n");
-	for (i = 0; i < ldev->ports; i++)
-		mlx5_core_info(dev, "\tport %d:%d\n", i + 1, ldev->v2p_map[i]);
+	if (flags & MLX5_LAG_FLAG_HASH_BASED) {
+		mlx5_infer_tx_enabled(tracker, ldev->ports, enabled_ports,
+				      &num_enabled);
+		for (i = 0; i < num_enabled; i++) {
+			err = scnprintf(buf + written, 4, "%d, ", enabled_ports[i] + 1);
+			if (err != 3)
+				return;
+			written += err;
+		}
+		buf[written - 2] = 0;
+		mlx5_core_info(dev, "lag map active ports: %s\n", buf);
+	} else {
+		for (i = 0; i < ldev->ports; i++) {
+			for (j  = 0; j < ldev->buckets; j++) {
+				idx = i * ldev->buckets + j;
+				err = scnprintf(buf + written, 10,
+						" port %d:%d", i + 1, ldev->v2p_map[idx]);
+				if (err != 9)
+					return;
+				written += err;
+			}
+		}
+		mlx5_core_info(dev, "lag map:%s\n", buf);
+	}
 }
 
 static int mlx5_lag_netdev_event(struct notifier_block *this,
@@ -174,6 +233,7 @@ static struct mlx5_lag *mlx5_lag_dev_alloc(struct mlx5_core_dev *dev)
 		mlx5_core_err(dev, "Failed to init multipath lag err=%d\n",
 			      err);
 	ldev->ports = MLX5_CAP_GEN(dev, num_lag_ports);
+	ldev->buckets = 1;
 
 	return ldev;
 }
@@ -200,28 +260,25 @@ static bool __mlx5_lag_is_sriov(struct mlx5_lag *ldev)
 	return !!(ldev->flags & MLX5_LAG_FLAG_SRIOV);
 }
 
-static void mlx5_infer_tx_disabled(struct lag_tracker *tracker, u8 num_ports,
-				   u8 *ports, int *num_disabled)
-{
-	int i;
-
-	*num_disabled = 0;
-	for (i = 0; i < num_ports; i++) {
-		if (!tracker->netdev_state[i].tx_enabled ||
-		    !tracker->netdev_state[i].link_up)
-			ports[(*num_disabled)++] = i;
-	}
-}
-
+/* Create a mapping between steering slots and active ports.
+ * As we have ldev->buckets slots per port first assume the native
+ * mapping should be used.
+ * If there are ports that are disabled fill the relevant slots
+ * with mapping that points to active ports.
+ */
 static void mlx5_infer_tx_affinity_mapping(struct lag_tracker *tracker,
-					   u8 num_ports, u8 *ports)
+					   u8 num_ports,
+					   u8 buckets,
+					   u8 *ports)
 {
 	int disabled[MLX5_MAX_PORTS] = {};
 	int enabled[MLX5_MAX_PORTS] = {};
 	int disabled_ports_num = 0;
 	int enabled_ports_num = 0;
+	int idx;
 	u32 rand;
 	int i;
+	int j;
 
 	for (i = 0; i < num_ports; i++) {
 		if (tracker->netdev_state[i].tx_enabled &&
@@ -231,9 +288,14 @@ static void mlx5_infer_tx_affinity_mapping(struct lag_tracker *tracker,
 			disabled[disabled_ports_num++] = i;
 	}
 
-	/* Use native mapping by default */
+	/* Use native mapping by default where each port's buckets
+	 * point the native port: 1 1 1 .. 1 2 2 2 ... 2 3 3 3 ... 3 etc
+	 */
 	for (i = 0; i < num_ports; i++)
-		ports[i] = MLX5_LAG_EGRESS_PORT_1 + i;
+		for (j = 0; j < buckets; j++) {
+			idx = i * buckets + j;
+			ports[idx] = MLX5_LAG_EGRESS_PORT_1 + i;
+		}
 
 	/* If all ports are disabled/enabled keep native mapping */
 	if (enabled_ports_num == num_ports ||
@@ -242,9 +304,10 @@ static void mlx5_infer_tx_affinity_mapping(struct lag_tracker *tracker,
 
 	/* Go over the disabled ports and for each assign a random active port */
 	for (i = 0; i < disabled_ports_num; i++) {
-		get_random_bytes(&rand, 4);
-
-		ports[disabled[i]] = enabled[rand % enabled_ports_num] + 1;
+		for (j = 0; j < buckets; j++) {
+			get_random_bytes(&rand, 4);
+			ports[disabled[i] * buckets + j] = enabled[rand % enabled_ports_num] + 1;
+		}
 	}
 }
 
@@ -317,28 +380,33 @@ static int _mlx5_modify_lag(struct mlx5_lag *ldev, u8 *ports)
 void mlx5_modify_lag(struct mlx5_lag *ldev,
 		     struct lag_tracker *tracker)
 {
+	u8 ports[MLX5_MAX_PORTS * MLX5_LAG_MAX_HASH_BUCKETS] = {};
 	struct mlx5_core_dev *dev0 = ldev->pf[MLX5_LAG_P1].dev;
-	u8 ports[MLX5_MAX_PORTS] = {};
+	int idx;
 	int err;
 	int i;
+	int j;
 
-	mlx5_infer_tx_affinity_mapping(tracker, ldev->ports, ports);
+	mlx5_infer_tx_affinity_mapping(tracker, ldev->ports, ldev->buckets, ports);
 
 	for (i = 0; i < ldev->ports; i++) {
-		if (ports[i] == ldev->v2p_map[i])
-			continue;
-		err = _mlx5_modify_lag(ldev, ports);
-		if (err) {
-			mlx5_core_err(dev0,
-				      "Failed to modify LAG (%d)\n",
-				      err);
-			return;
-		}
-		memcpy(ldev->v2p_map, ports, sizeof(ports[0]) *
-		       ldev->ports);
+		for (j = 0; j < ldev->buckets; j++) {
+			idx = i * ldev->buckets + j;
+			if (ports[idx] == ldev->v2p_map[idx])
+				continue;
+			err = _mlx5_modify_lag(ldev, ports);
+			if (err) {
+				mlx5_core_err(dev0,
+					      "Failed to modify LAG (%d)\n",
+					      err);
+				return;
+			}
+			memcpy(ldev->v2p_map, ports, sizeof(ports));
 
-		mlx5_lag_print_mapping(dev0, ldev);
-		break;
+			mlx5_lag_print_mapping(dev0, ldev, tracker,
+					       ldev->flags);
+			break;
+		}
 	}
 
 	if (tracker->tx_type == NETDEV_LAG_TX_TYPE_ACTIVEBACKUP &&
@@ -357,6 +425,8 @@ static int mlx5_lag_set_port_sel_mode_roce(struct mlx5_lag *ldev,
 		if (!MLX5_CAP_PORT_SELECTION(dev0->dev, port_select_flow_table))
 			return -EINVAL;
 		*flags |= MLX5_LAG_FLAG_HASH_BASED;
+		if (ldev->ports > 2)
+			ldev->buckets = MLX5_LAG_MAX_HASH_BUCKETS;
 	}
 
 	return 0;
@@ -370,6 +440,7 @@ static int mlx5_lag_set_port_sel_mode_offloads(struct mlx5_lag *ldev,
 	if (MLX5_CAP_PORT_SELECTION(dev0->dev, port_select_flow_table) &&
 	    tracker->tx_type == NETDEV_LAG_TX_TYPE_HASH)
 		*flags |= MLX5_LAG_FLAG_HASH_BASED;
+
 	return 0;
 }
 
@@ -399,7 +470,7 @@ static int mlx5_create_lag(struct mlx5_lag *ldev,
 	u32 in[MLX5_ST_SZ_DW(destroy_lag_in)] = {};
 	int err;
 
-	mlx5_lag_print_mapping(dev0, ldev);
+	mlx5_lag_print_mapping(dev0, ldev, tracker, flags);
 	mlx5_core_info(dev0, "shared_fdb:%d mode:%s\n",
 		       shared_fdb, get_str_port_sel_mode(flags));
 
@@ -439,11 +510,12 @@ int mlx5_activate_lag(struct mlx5_lag *ldev,
 	struct mlx5_core_dev *dev0 = ldev->pf[MLX5_LAG_P1].dev;
 	int err;
 
-	mlx5_infer_tx_affinity_mapping(tracker, ldev->ports, ldev->v2p_map);
 	err = mlx5_lag_set_port_sel_mode(ldev, tracker, &flags);
 	if (err)
 		return err;
 
+	mlx5_infer_tx_affinity_mapping(tracker, ldev->ports, ldev->buckets, ldev->v2p_map);
+
 	if (flags & MLX5_LAG_FLAG_HASH_BASED) {
 		err = mlx5_lag_port_sel_create(ldev, tracker->hash_type,
 					       ldev->v2p_map);
@@ -1265,7 +1337,7 @@ u8 mlx5_lag_get_slave_port(struct mlx5_core_dev *dev,
 		}
 	}
 
-	port = ldev->v2p_map[port];
+	port = ldev->v2p_map[port * ldev->buckets];
 
 unlock:
 	spin_unlock(&lag_lock);

drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h

@@ -4,6 +4,7 @@
 #ifndef __MLX5_LAG_H__
 #define __MLX5_LAG_H__
 
+#define MLX5_LAG_MAX_HASH_BUCKETS 16
 #include "mlx5_core.h"
 #include "mp.h"
 #include "port_sel.h"
@@ -46,9 +47,10 @@ struct lag_tracker {
 struct mlx5_lag {
 	u8                        flags;
 	u8			  ports;
+	u8			  buckets;
 	int			  mode_changes_in_progress;
 	bool			  shared_fdb;
-	u8                        v2p_map[MLX5_MAX_PORTS];
+	u8			  v2p_map[MLX5_MAX_PORTS * MLX5_LAG_MAX_HASH_BUCKETS];
 	struct kref               ref;
 	struct lag_func           pf[MLX5_MAX_PORTS];
 	struct lag_tracker        tracker;