net/mlx5e: Use a slow path rule instead if vxlan neighbour isn't available

When adding a vxlan tc rule, and a neighbour isn't available, we
don't insert any rule to hardware. Once we enable offloading flows
with multiple priorities, a packet that should have matched this rule
will continue in hardware pipeline and might match a wrong one.

This is unlike in tc software path where it will be matched and
forwarded to the vxlan device (which will cause a ARP lookup
eventually) and stop processing further tc filters.

To address that, when when a neighbour isn't available (EAGAIN from
attach_encap), or gets deleted, change the original action to be a
forward to slow path instead. Neighbour update will restore the original
action once the neighbour becomes available. This will be done atomically
so at any given time we will have a the correct match.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 1786e25644acb60cfc3ef3c360095fe6584c4675..cb66964aa1ffcedd786c45784719e7c1e6cde2a3 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -74,6 +74,7 @@ enum {
        MLX5E_TC_FLOW_OFFLOADED = BIT(MLX5E_TC_FLOW_BASE + 2),
        MLX5E_TC_FLOW_HAIRPIN   = BIT(MLX5E_TC_FLOW_BASE + 3),
        MLX5E_TC_FLOW_HAIRPIN_RSS = BIT(MLX5E_TC_FLOW_BASE + 4),
+       MLX5E_TC_FLOW_SLOW        = BIT(MLX5E_TC_FLOW_BASE + 5),
 };
 
 #define MLX5E_TC_MAX_SPLITS 1
@@ -82,7 +83,7 @@ struct mlx5e_tc_flow {
        struct rhash_head       node;
        struct mlx5e_priv       *priv;
        u64                     cookie;
-       u8                      flags;
+       u16                     flags;
        struct mlx5_flow_handle *rule[MLX5E_TC_MAX_SPLITS + 1];
        struct list_head        encap;   /* flows sharing the same encap ID */
        struct list_head        mod_hdr; /* flows sharing the same mod hdr ID */
@@ -860,6 +861,36 @@ mlx5e_tc_unoffload_fdb_rules(struct mlx5_eswitch *esw,
        mlx5_eswitch_del_offloaded_rule(esw, flow->rule[0], attr);
 }
 
+static struct mlx5_flow_handle *
+mlx5e_tc_offload_to_slow_path(struct mlx5_eswitch *esw,
+                             struct mlx5e_tc_flow *flow,
+                             struct mlx5_flow_spec *spec,
+                             struct mlx5_esw_flow_attr *slow_attr)
+{
+       struct mlx5_flow_handle *rule;
+
+       memcpy(slow_attr, flow->esw_attr, sizeof(*slow_attr));
+       slow_attr->action = MLX5_FLOW_CONTEXT_ACTION_FWD_DEST,
+       slow_attr->mirror_count = 0,
+       slow_attr->dest_chain = FDB_SLOW_PATH_CHAIN,
+
+       rule = mlx5e_tc_offload_fdb_rules(esw, flow, spec, slow_attr);
+       if (!IS_ERR(rule))
+               flow->flags |= MLX5E_TC_FLOW_SLOW;
+
+       return rule;
+}
+
+static void
+mlx5e_tc_unoffload_from_slow_path(struct mlx5_eswitch *esw,
+                                 struct mlx5e_tc_flow *flow,
+                                 struct mlx5_esw_flow_attr *slow_attr)
+{
+       memcpy(slow_attr, flow->esw_attr, sizeof(*slow_attr));
+       mlx5e_tc_unoffload_fdb_rules(esw, flow, slow_attr);
+       flow->flags &= ~MLX5E_TC_FLOW_SLOW;
+}
+
 static int
 mlx5e_tc_add_fdb_flow(struct mlx5e_priv *priv,
                      struct mlx5e_tc_flow_parse_attr *parse_attr,
@@ -917,15 +948,21 @@ mlx5e_tc_add_fdb_flow(struct mlx5e_priv *priv,
        /* we get here if (1) there's no error or when
         * (2) there's an encap action and we're on -EAGAIN (no valid neigh)
         */
-       if (encap_err != -EAGAIN) {
+       if (encap_err == -EAGAIN) {
+               /* continue with goto slow path rule instead */
+               struct mlx5_esw_flow_attr slow_attr;
+
+               flow->rule[0] = mlx5e_tc_offload_to_slow_path(esw, flow, &parse_attr->spec, &slow_attr);
+       } else {
                flow->rule[0] = mlx5e_tc_offload_fdb_rules(esw, flow, &parse_attr->spec, attr);
-               if (IS_ERR(flow->rule[0])) {
-                       err = PTR_ERR(flow->rule[0]);
-                       goto err_add_rule;
-               }
        }
 
-       return encap_err;
+       if (IS_ERR(flow->rule[0])) {
+               err = PTR_ERR(flow->rule[0]);
+               goto err_add_rule;
+       }
+
+       return 0;
 
 err_add_rule:
        mlx5_fc_destroy(esw->dev, counter);
@@ -946,9 +983,14 @@ static void mlx5e_tc_del_fdb_flow(struct mlx5e_priv *priv,
 {
        struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
        struct mlx5_esw_flow_attr *attr = flow->esw_attr;
+       struct mlx5_esw_flow_attr slow_attr;
 
-       if (flow->flags & MLX5E_TC_FLOW_OFFLOADED)
-               mlx5e_tc_unoffload_fdb_rules(esw, flow, flow->esw_attr);
+       if (flow->flags & MLX5E_TC_FLOW_OFFLOADED) {
+               if (flow->flags & MLX5E_TC_FLOW_SLOW)
+                       mlx5e_tc_unoffload_from_slow_path(esw, flow, &slow_attr);
+               else
+                       mlx5e_tc_unoffload_fdb_rules(esw, flow, attr);
+       }
 
        mlx5_eswitch_del_vlan_action(esw, attr);
 
@@ -968,7 +1010,7 @@ void mlx5e_tc_encap_flows_add(struct mlx5e_priv *priv,
                              struct mlx5e_encap_entry *e)
 {
        struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
-       struct mlx5_esw_flow_attr *esw_attr;
+       struct mlx5_esw_flow_attr slow_attr, *esw_attr;
        struct mlx5_flow_handle *rule;
        struct mlx5_flow_spec *spec;
        struct mlx5e_tc_flow *flow;
@@ -991,6 +1033,7 @@ void mlx5e_tc_encap_flows_add(struct mlx5e_priv *priv,
                esw_attr->encap_id = e->encap_id;
                spec = &esw_attr->parse_attr->spec;
 
+               /* update from slow path rule to encap rule */
                rule = mlx5e_tc_offload_fdb_rules(esw, flow, spec, esw_attr);
                if (IS_ERR(rule)) {
                        err = PTR_ERR(rule);
@@ -998,6 +1041,9 @@ void mlx5e_tc_encap_flows_add(struct mlx5e_priv *priv,
                                       err);
                        continue;
                }
+
+               mlx5e_tc_unoffload_from_slow_path(esw, flow, &slow_attr);
+               flow->flags |= MLX5E_TC_FLOW_OFFLOADED; /* was unset when slow path rule removed */
                flow->rule[0] = rule;
        }
 }
@@ -1006,11 +1052,28 @@ void mlx5e_tc_encap_flows_del(struct mlx5e_priv *priv,
                              struct mlx5e_encap_entry *e)
 {
        struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
+       struct mlx5_esw_flow_attr slow_attr;
+       struct mlx5_flow_handle *rule;
+       struct mlx5_flow_spec *spec;
        struct mlx5e_tc_flow *flow;
+       int err;
 
        list_for_each_entry(flow, &e->flows, encap) {
-               if (flow->flags & MLX5E_TC_FLOW_OFFLOADED)
-                       mlx5e_tc_unoffload_fdb_rules(esw, flow, flow->esw_attr);
+               spec = &flow->esw_attr->parse_attr->spec;
+
+               /* update from encap rule to slow path rule */
+               rule = mlx5e_tc_offload_to_slow_path(esw, flow, spec, &slow_attr);
+
+               if (IS_ERR(rule)) {
+                       err = PTR_ERR(rule);
+                       mlx5_core_warn(priv->mdev, "Failed to update slow path (encap) flow, %d\n",
+                                      err);
+                       continue;
+               }
+
+               mlx5e_tc_unoffload_fdb_rules(esw, flow, flow->esw_attr);
+               flow->flags |= MLX5E_TC_FLOW_OFFLOADED; /* was unset when fast path rule removed */
+               flow->rule[0] = rule;
        }
 
        if (e->flags & MLX5_ENCAP_ENTRY_VALID) {
@@ -2888,9 +2951,9 @@ static int parse_tc_fdb_actions(struct mlx5e_priv *priv, struct tcf_exts *exts,
        return 0;
 }
 
-static void get_flags(int flags, u8 *flow_flags)
+static void get_flags(int flags, u16 *flow_flags)
 {
-       u8 __flow_flags = 0;
+       u16 __flow_flags = 0;
 
        if (flags & MLX5E_TC_INGRESS)
                __flow_flags |= MLX5E_TC_FLOW_INGRESS;
@@ -2921,7 +2984,7 @@ static struct rhashtable *get_tc_ht(struct mlx5e_priv *priv)
 
 static int
 mlx5e_alloc_flow(struct mlx5e_priv *priv, int attr_size,
-                struct tc_cls_flower_offload *f, u8 flow_flags,
+                struct tc_cls_flower_offload *f, u16 flow_flags,
                 struct mlx5e_tc_flow_parse_attr **__parse_attr,
                 struct mlx5e_tc_flow **__flow)
 {
@@ -2958,7 +3021,7 @@ err_free:
 static int
 mlx5e_add_fdb_flow(struct mlx5e_priv *priv,
                   struct tc_cls_flower_offload *f,
-                  u8 flow_flags,
+                  u16 flow_flags,
                   struct mlx5e_tc_flow **__flow)
 {
        struct netlink_ext_ack *extack = f->common.extack;
@@ -2978,12 +3041,9 @@ mlx5e_add_fdb_flow(struct mlx5e_priv *priv,
                goto err_free;
 
        err = mlx5e_tc_add_fdb_flow(priv, parse_attr, flow, extack);
-       if (err && err != -EAGAIN)
+       if (err)
                goto err_free;
 
-       if (!err)
-               flow->flags |= MLX5E_TC_FLOW_OFFLOADED;
-
        if (!(flow->esw_attr->action &
              MLX5_FLOW_CONTEXT_ACTION_PACKET_REFORMAT))
                kvfree(parse_attr);
@@ -3002,7 +3062,7 @@ out:
 static int
 mlx5e_add_nic_flow(struct mlx5e_priv *priv,
                   struct tc_cls_flower_offload *f,
-                  u8 flow_flags,
+                  u16 flow_flags,
                   struct mlx5e_tc_flow **__flow)
 {
        struct netlink_ext_ack *extack = f->common.extack;
@@ -3045,7 +3105,7 @@ mlx5e_tc_add_flow(struct mlx5e_priv *priv,
                  struct mlx5e_tc_flow **flow)
 {
        struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
-       u8 flow_flags;
+       u16 flow_flags;
        int err;
 
        get_flags(flags, &flow_flags);