nfp: flower: validate merge hint flows

Two flows can be merged if the second flow (after recirculation) matches
on bits that are either matched on or explicitly set by the first flow.
This means that if a packet hits flow 1 and recirculates then it is
guaranteed to hit flow 2.

Add a 'can_merge' function that determines if 2 sub_flows in a merge hint
can be validly merged to a single flow.
Signed-off-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -55,6 +55,28 @@
 	 BIT(FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS) | \
 	 BIT(FLOW_DISSECTOR_KEY_ENC_PORTS))
 
+#define NFP_FLOWER_MERGE_FIELDS \
+	(NFP_FLOWER_LAYER_PORT | \
+	 NFP_FLOWER_LAYER_MAC | \
+	 NFP_FLOWER_LAYER_TP | \
+	 NFP_FLOWER_LAYER_IPV4 | \
+	 NFP_FLOWER_LAYER_IPV6)
+
+struct nfp_flower_merge_check {
+	union {
+		struct {
+			__be16 tci;
+			struct nfp_flower_mac_mpls l2;
+			struct nfp_flower_tp_ports l4;
+			union {
+				struct nfp_flower_ipv4 ipv4;
+				struct nfp_flower_ipv6 ipv6;
+			};
+		};
+		unsigned long vals[8];
+	};
+};
+
 static int
 nfp_flower_xmit_flow(struct nfp_app *app, struct nfp_fl_payload *nfp_flow,
 		     u8 mtype)
@@ -388,6 +410,206 @@ nfp_flower_allocate_new(struct nfp_fl_key_ls *key_layer)
 	return NULL;
 }
 
+static int
+nfp_flower_update_merge_with_actions(struct nfp_fl_payload *flow,
+				     struct nfp_flower_merge_check *merge,
+				     u8 *last_act_id, int *act_out)
+{
+	struct nfp_fl_set_ipv6_tc_hl_fl *ipv6_tc_hl_fl;
+	struct nfp_fl_set_ip4_ttl_tos *ipv4_ttl_tos;
+	struct nfp_fl_set_ip4_addrs *ipv4_add;
+	struct nfp_fl_set_ipv6_addr *ipv6_add;
+	struct nfp_fl_push_vlan *push_vlan;
+	struct nfp_fl_set_tport *tport;
+	struct nfp_fl_set_eth *eth;
+	struct nfp_fl_act_head *a;
+	unsigned int act_off = 0;
+	u8 act_id = 0;
+	u8 *ports;
+	int i;
+
+	while (act_off < flow->meta.act_len) {
+		a = (struct nfp_fl_act_head *)&flow->action_data[act_off];
+		act_id = a->jump_id;
+
+		switch (act_id) {
+		case NFP_FL_ACTION_OPCODE_OUTPUT:
+			if (act_out)
+				(*act_out)++;
+			break;
+		case NFP_FL_ACTION_OPCODE_PUSH_VLAN:
+			push_vlan = (struct nfp_fl_push_vlan *)a;
+			if (push_vlan->vlan_tci)
+				merge->tci = cpu_to_be16(0xffff);
+			break;
+		case NFP_FL_ACTION_OPCODE_POP_VLAN:
+			merge->tci = cpu_to_be16(0);
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_IPV4_TUNNEL:
+			/* New tunnel header means l2 to l4 can be matched. */
+			eth_broadcast_addr(&merge->l2.mac_dst[0]);
+			eth_broadcast_addr(&merge->l2.mac_src[0]);
+			memset(&merge->l4, 0xff,
+			       sizeof(struct nfp_flower_tp_ports));
+			memset(&merge->ipv4, 0xff,
+			       sizeof(struct nfp_flower_ipv4));
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_ETHERNET:
+			eth = (struct nfp_fl_set_eth *)a;
+			for (i = 0; i < ETH_ALEN; i++)
+				merge->l2.mac_dst[i] |= eth->eth_addr_mask[i];
+			for (i = 0; i < ETH_ALEN; i++)
+				merge->l2.mac_src[i] |=
+					eth->eth_addr_mask[ETH_ALEN + i];
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_IPV4_ADDRS:
+			ipv4_add = (struct nfp_fl_set_ip4_addrs *)a;
+			merge->ipv4.ipv4_src |= ipv4_add->ipv4_src_mask;
+			merge->ipv4.ipv4_dst |= ipv4_add->ipv4_dst_mask;
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_IPV4_TTL_TOS:
+			ipv4_ttl_tos = (struct nfp_fl_set_ip4_ttl_tos *)a;
+			merge->ipv4.ip_ext.ttl |= ipv4_ttl_tos->ipv4_ttl_mask;
+			merge->ipv4.ip_ext.tos |= ipv4_ttl_tos->ipv4_tos_mask;
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_IPV6_SRC:
+			ipv6_add = (struct nfp_fl_set_ipv6_addr *)a;
+			for (i = 0; i < 4; i++)
+				merge->ipv6.ipv6_src.in6_u.u6_addr32[i] |=
+					ipv6_add->ipv6[i].mask;
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_IPV6_DST:
+			ipv6_add = (struct nfp_fl_set_ipv6_addr *)a;
+			for (i = 0; i < 4; i++)
+				merge->ipv6.ipv6_dst.in6_u.u6_addr32[i] |=
+					ipv6_add->ipv6[i].mask;
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_IPV6_TC_HL_FL:
+			ipv6_tc_hl_fl = (struct nfp_fl_set_ipv6_tc_hl_fl *)a;
+			merge->ipv6.ip_ext.ttl |=
+				ipv6_tc_hl_fl->ipv6_hop_limit_mask;
+			merge->ipv6.ip_ext.tos |= ipv6_tc_hl_fl->ipv6_tc_mask;
+			merge->ipv6.ipv6_flow_label_exthdr |=
+				ipv6_tc_hl_fl->ipv6_label_mask;
+			break;
+		case NFP_FL_ACTION_OPCODE_SET_UDP:
+		case NFP_FL_ACTION_OPCODE_SET_TCP:
+			tport = (struct nfp_fl_set_tport *)a;
+			ports = (u8 *)&merge->l4.port_src;
+			for (i = 0; i < 4; i++)
+				ports[i] |= tport->tp_port_mask[i];
+			break;
+		case NFP_FL_ACTION_OPCODE_PRE_TUNNEL:
+		case NFP_FL_ACTION_OPCODE_PRE_LAG:
+		case NFP_FL_ACTION_OPCODE_PUSH_GENEVE:
+			break;
+		default:
+			return -EOPNOTSUPP;
+		}
+
+		act_off += a->len_lw << NFP_FL_LW_SIZ;
+	}
+
+	if (last_act_id)
+		*last_act_id = act_id;
+
+	return 0;
+}
+
+static int
+nfp_flower_populate_merge_match(struct nfp_fl_payload *flow,
+				struct nfp_flower_merge_check *merge,
+				bool extra_fields)
+{
+	struct nfp_flower_meta_tci *meta_tci;
+	u8 *mask = flow->mask_data;
+	u8 key_layer, match_size;
+
+	memset(merge, 0, sizeof(struct nfp_flower_merge_check));
+
+	meta_tci = (struct nfp_flower_meta_tci *)mask;
+	key_layer = meta_tci->nfp_flow_key_layer;
+
+	if (key_layer & ~NFP_FLOWER_MERGE_FIELDS && !extra_fields)
+		return -EOPNOTSUPP;
+
+	merge->tci = meta_tci->tci;
+	mask += sizeof(struct nfp_flower_meta_tci);
+
+	if (key_layer & NFP_FLOWER_LAYER_EXT_META)
+		mask += sizeof(struct nfp_flower_ext_meta);
+
+	mask += sizeof(struct nfp_flower_in_port);
+
+	if (key_layer & NFP_FLOWER_LAYER_MAC) {
+		match_size = sizeof(struct nfp_flower_mac_mpls);
+		memcpy(&merge->l2, mask, match_size);
+		mask += match_size;
+	}
+
+	if (key_layer & NFP_FLOWER_LAYER_TP) {
+		match_size = sizeof(struct nfp_flower_tp_ports);
+		memcpy(&merge->l4, mask, match_size);
+		mask += match_size;
+	}
+
+	if (key_layer & NFP_FLOWER_LAYER_IPV4) {
+		match_size = sizeof(struct nfp_flower_ipv4);
+		memcpy(&merge->ipv4, mask, match_size);
+	}
+
+	if (key_layer & NFP_FLOWER_LAYER_IPV6) {
+		match_size = sizeof(struct nfp_flower_ipv6);
+		memcpy(&merge->ipv6, mask, match_size);
+	}
+
+	return 0;
+}
+
+static int
+nfp_flower_can_merge(struct nfp_fl_payload *sub_flow1,
+		     struct nfp_fl_payload *sub_flow2)
+{
+	/* Two flows can be merged if sub_flow2 only matches on bits that are
+	 * either matched by sub_flow1 or set by a sub_flow1 action. This
+	 * ensures that every packet that hits sub_flow1 and recirculates is
+	 * guaranteed to hit sub_flow2.
+	 */
+	struct nfp_flower_merge_check sub_flow1_merge, sub_flow2_merge;
+	int err, act_out = 0;
+	u8 last_act_id = 0;
+
+	err = nfp_flower_populate_merge_match(sub_flow1, &sub_flow1_merge,
+					      true);
+	if (err)
+		return err;
+
+	err = nfp_flower_populate_merge_match(sub_flow2, &sub_flow2_merge,
+					      false);
+	if (err)
+		return err;
+
+	err = nfp_flower_update_merge_with_actions(sub_flow1, &sub_flow1_merge,
+						   &last_act_id, &act_out);
+	if (err)
+		return err;
+
+	/* Must only be 1 output action and it must be the last in sequence. */
+	if (act_out != 1 || last_act_id != NFP_FL_ACTION_OPCODE_OUTPUT)
+		return -EOPNOTSUPP;
+
+	/* Reject merge if sub_flow2 matches on something that is not matched
+	 * on or set in an action by sub_flow1.
+	 */
+	err = bitmap_andnot(sub_flow2_merge.vals, sub_flow2_merge.vals,
+			    sub_flow1_merge.vals,
+			    sizeof(struct nfp_flower_merge_check) * 8);
+	if (err)
+		return -EINVAL;
+
+	return 0;
+}
+
 /**
  * nfp_flower_merge_offloaded_flows() - Merge 2 existing flows to single flow.
  * @app:	Pointer to the APP handle
@@ -403,6 +625,12 @@ int nfp_flower_merge_offloaded_flows(struct nfp_app *app,
 				     struct nfp_fl_payload *sub_flow1,
 				     struct nfp_fl_payload *sub_flow2)
 {
+	int err;
+
+	err = nfp_flower_can_merge(sub_flow1, sub_flow2);
+	if (err)
+		return err;
+
 	return -EOPNOTSUPP;
 }