net/mlx5e: Implement CT entry update

With support for UDP NEW offload the flow_table may now send updates for
existing flows. Support properly replacing existing entries by updating
flow restore_cookie and replacing the rule with new one with the same match
but new mod_hdr action that sets updated ctinfo.
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Paul Blakey <paulb@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c

@@ -871,6 +871,68 @@ mlx5_tc_ct_entry_add_rule(struct mlx5_tc_ct_priv *ct_priv,
 	return err;
 }
 
+static int
+mlx5_tc_ct_entry_replace_rule(struct mlx5_tc_ct_priv *ct_priv,
+			      struct flow_rule *flow_rule,
+			      struct mlx5_ct_entry *entry,
+			      bool nat, u8 zone_restore_id)
+{
+	struct mlx5_ct_zone_rule *zone_rule = &entry->zone_rules[nat];
+	struct mlx5_flow_attr *attr = zone_rule->attr, *old_attr;
+	struct mlx5e_mod_hdr_handle *mh;
+	struct mlx5_ct_fs_rule *rule;
+	struct mlx5_flow_spec *spec;
+	int err;
+
+	spec = kvzalloc(sizeof(*spec), GFP_KERNEL);
+	if (!spec)
+		return -ENOMEM;
+
+	old_attr = mlx5_alloc_flow_attr(ct_priv->ns_type);
+	if (!old_attr) {
+		err = -ENOMEM;
+		goto err_attr;
+	}
+	*old_attr = *attr;
+
+	err = mlx5_tc_ct_entry_create_mod_hdr(ct_priv, attr, flow_rule, &mh, zone_restore_id,
+					      nat, mlx5_tc_ct_entry_has_nat(entry));
+	if (err) {
+		ct_dbg("Failed to create ct entry mod hdr");
+		goto err_mod_hdr;
+	}
+
+	mlx5_tc_ct_set_tuple_match(ct_priv, spec, flow_rule);
+	mlx5e_tc_match_to_reg_match(spec, ZONE_TO_REG, entry->tuple.zone, MLX5_CT_ZONE_MASK);
+
+	rule = ct_priv->fs_ops->ct_rule_add(ct_priv->fs, spec, attr, flow_rule);
+	if (IS_ERR(rule)) {
+		err = PTR_ERR(rule);
+		ct_dbg("Failed to add replacement ct entry rule, nat: %d", nat);
+		goto err_rule;
+	}
+
+	ct_priv->fs_ops->ct_rule_del(ct_priv->fs, zone_rule->rule);
+	zone_rule->rule = rule;
+	mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, old_attr, zone_rule->mh);
+	zone_rule->mh = mh;
+
+	kfree(old_attr);
+	kvfree(spec);
+	ct_dbg("Replaced ct entry rule in zone %d", entry->tuple.zone);
+
+	return 0;
+
+err_rule:
+	mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, zone_rule->attr, mh);
+	mlx5_put_label_mapping(ct_priv, attr->ct_attr.ct_labels_id);
+err_mod_hdr:
+	kfree(old_attr);
+err_attr:
+	kvfree(spec);
+	return err;
+}
+
 static bool
 mlx5_tc_ct_entry_valid(struct mlx5_ct_entry *entry)
 {
@@ -1065,6 +1127,52 @@ mlx5_tc_ct_entry_add_rules(struct mlx5_tc_ct_priv *ct_priv,
 	return err;
 }
 
+static int
+mlx5_tc_ct_entry_replace_rules(struct mlx5_tc_ct_priv *ct_priv,
+			       struct flow_rule *flow_rule,
+			       struct mlx5_ct_entry *entry,
+			       u8 zone_restore_id)
+{
+	int err;
+
+	err = mlx5_tc_ct_entry_replace_rule(ct_priv, flow_rule, entry, false,
+					    zone_restore_id);
+	if (err)
+		return err;
+
+	err = mlx5_tc_ct_entry_replace_rule(ct_priv, flow_rule, entry, true,
+					    zone_restore_id);
+	if (err)
+		mlx5_tc_ct_entry_del_rule(ct_priv, entry, false);
+	return err;
+}
+
+static int
+mlx5_tc_ct_block_flow_offload_replace(struct mlx5_ct_ft *ft, struct flow_rule *flow_rule,
+				      struct mlx5_ct_entry *entry, unsigned long cookie)
+{
+	struct mlx5_tc_ct_priv *ct_priv = ft->ct_priv;
+	int err;
+
+	err = mlx5_tc_ct_entry_replace_rules(ct_priv, flow_rule, entry, ft->zone_restore_id);
+	if (!err)
+		return 0;
+
+	/* If failed to update the entry, then look it up again under ht_lock
+	 * protection and properly delete it.
+	 */
+	spin_lock_bh(&ct_priv->ht_lock);
+	entry = rhashtable_lookup_fast(&ft->ct_entries_ht, &cookie, cts_ht_params);
+	if (entry) {
+		rhashtable_remove_fast(&ft->ct_entries_ht, &entry->node, cts_ht_params);
+		spin_unlock_bh(&ct_priv->ht_lock);
+		mlx5_tc_ct_entry_put(entry);
+	} else {
+		spin_unlock_bh(&ct_priv->ht_lock);
+	}
+	return err;
+}
+
 static int
 mlx5_tc_ct_block_flow_offload_add(struct mlx5_ct_ft *ft,
 				  struct flow_cls_offload *flow)
@@ -1087,9 +1195,17 @@ mlx5_tc_ct_block_flow_offload_add(struct mlx5_ct_ft *ft,
 	spin_lock_bh(&ct_priv->ht_lock);
 	entry = rhashtable_lookup_fast(&ft->ct_entries_ht, &cookie, cts_ht_params);
 	if (entry && refcount_inc_not_zero(&entry->refcnt)) {
+		if (entry->restore_cookie == meta_action->ct_metadata.cookie) {
+			spin_unlock_bh(&ct_priv->ht_lock);
+			mlx5_tc_ct_entry_put(entry);
+			return -EEXIST;
+		}
+		entry->restore_cookie = meta_action->ct_metadata.cookie;
 		spin_unlock_bh(&ct_priv->ht_lock);
+
+		err = mlx5_tc_ct_block_flow_offload_replace(ft, flow_rule, entry, cookie);
 		mlx5_tc_ct_entry_put(entry);
-		return -EEXIST;
+		return err;
 	}
 	spin_unlock_bh(&ct_priv->ht_lock);