nfp: flower: utilize the tuple iifidx in offloading ct flows

The device info from which conntrack originates is stored in metadata
field of the ct flow to offload now, driver can utilize it to reduce
the number of offloaded flows.

v2: Drop inline keyword from get_netdev_from_rule() signature.
    The compiler can decide.
Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20220429075124.128589-1-simon.horman@corigine.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/netronome/nfp/flower/conntrack.c

@@ -83,6 +83,10 @@ static int nfp_ct_merge_check(struct nfp_fl_ct_flow_entry *entry1,
 				 entry2->rule->match.dissector->used_keys;
 	bool out;
 
+	if (entry1->netdev && entry2->netdev &&
+	    entry1->netdev != entry2->netdev)
+		return -EINVAL;
+
 	/* check the overlapped fields one by one, the unmasked part
 	 * should not conflict with each other.
 	 */
@@ -914,7 +918,7 @@ static int nfp_ct_do_nft_merge(struct nfp_fl_ct_zone_entry *zt,
 	/* Check that the two tc flows are also compatible with
 	 * the nft entry. No need to check the pre_ct and post_ct
 	 * entries as that was already done during pre_merge.
-	 * The nft entry does not have a netdev or chain populated, so
+	 * The nft entry does not have a chain populated, so
 	 * skip this check.
 	 */
 	err = nfp_ct_merge_check(pre_ct_entry, nft_entry);
@@ -999,8 +1003,6 @@ static int nfp_ct_do_tc_merge(struct nfp_fl_ct_zone_entry *zt,
 		pre_ct_entry = ct_entry2;
 	}
 
-	if (post_ct_entry->netdev != pre_ct_entry->netdev)
-		return -EINVAL;
 	/* Checks that the chain_index of the filter matches the
 	 * chain_index of the GOTO action.
 	 */
@@ -1114,6 +1116,20 @@ nfp_fl_ct_zone_entry *get_nfp_zone_entry(struct nfp_flower_priv *priv,
 	return ERR_PTR(err);
 }
 
+static struct net_device *get_netdev_from_rule(struct flow_rule *rule)
+{
+	if (flow_rule_match_key(rule, FLOW_DISSECTOR_KEY_META)) {
+		struct flow_match_meta match;
+
+		flow_rule_match_meta(rule, &match);
+		if (match.key->ingress_ifindex & match.mask->ingress_ifindex)
+			return __dev_get_by_index(&init_net,
+						  match.key->ingress_ifindex);
+	}
+
+	return NULL;
+}
+
 static struct
 nfp_fl_ct_flow_entry *nfp_fl_ct_add_flow(struct nfp_fl_ct_zone_entry *zt,
 					 struct net_device *netdev,
@@ -1154,6 +1170,9 @@ nfp_fl_ct_flow_entry *nfp_fl_ct_add_flow(struct nfp_fl_ct_zone_entry *zt,
 		entry->rule->match.dissector = &nft_match->dissector;
 		entry->rule->match.mask = &nft_match->mask;
 		entry->rule->match.key = &nft_match->key;
+
+		if (!netdev)
+			netdev = get_netdev_from_rule(entry->rule);
 	} else {
 		entry->rule->match.dissector = flow->rule->match.dissector;
 		entry->rule->match.mask = flow->rule->match.mask;