nfp: flower: handle merge hint messages

If a merge hint is received containing 2 flows that are matched via an
implicit recirculation (sending to and matching on an internal port), fw
reports that the flows (called sub_flows) may be able to be combined to a
single flow.

Add infastructure to accept and process merge hint messages. The actual
merging of the flows is left as a stub call.
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/cmsg.c

@@ -204,6 +204,50 @@ nfp_flower_cmsg_portreify_rx(struct nfp_app *app, struct sk_buff *skb)
 	wake_up(&priv->reify_wait_queue);
 }
 
+static void
+nfp_flower_cmsg_merge_hint_rx(struct nfp_app *app, struct sk_buff *skb)
+{
+	unsigned int msg_len = nfp_flower_cmsg_get_data_len(skb);
+	struct nfp_flower_cmsg_merge_hint *msg;
+	struct nfp_fl_payload *sub_flows[2];
+	int err, i, flow_cnt;
+
+	msg = nfp_flower_cmsg_get_data(skb);
+	/* msg->count starts at 0 and always assumes at least 1 entry. */
+	flow_cnt = msg->count + 1;
+
+	if (msg_len < struct_size(msg, flow, flow_cnt)) {
+		nfp_flower_cmsg_warn(app, "Merge hint ctrl msg too short - %d bytes but expect %ld\n",
+				     msg_len, struct_size(msg, flow, flow_cnt));
+		return;
+	}
+
+	if (flow_cnt != 2) {
+		nfp_flower_cmsg_warn(app, "Merge hint contains %d flows - two are expected\n",
+				     flow_cnt);
+		return;
+	}
+
+	rtnl_lock();
+	for (i = 0; i < flow_cnt; i++) {
+		u32 ctx = be32_to_cpu(msg->flow[i].host_ctx);
+
+		sub_flows[i] = nfp_flower_get_fl_payload_from_ctx(app, ctx);
+		if (!sub_flows[i]) {
+			nfp_flower_cmsg_warn(app, "Invalid flow in merge hint\n");
+			goto err_rtnl_unlock;
+		}
+	}
+
+	err = nfp_flower_merge_offloaded_flows(app, sub_flows[0], sub_flows[1]);
+	/* Only warn on memory fail. Hint veto will not break functionality. */
+	if (err == -ENOMEM)
+		nfp_flower_cmsg_warn(app, "Flow merge memory fail.\n");
+
+err_rtnl_unlock:
+	rtnl_unlock();
+}
+
 static void
 nfp_flower_cmsg_process_one_rx(struct nfp_app *app, struct sk_buff *skb)
 {
@@ -223,8 +267,10 @@ nfp_flower_cmsg_process_one_rx(struct nfp_app *app, struct sk_buff *skb)
 		nfp_flower_cmsg_portmod_rx(app, skb);
 		break;
 	case NFP_FLOWER_CMSG_TYPE_MERGE_HINT:
-		if (app_priv->flower_ext_feats & NFP_FL_FEATS_FLOW_MERGE)
+		if (app_priv->flower_ext_feats & NFP_FL_FEATS_FLOW_MERGE) {
+			nfp_flower_cmsg_merge_hint_rx(app, skb);
 			break;
+		}
 		goto err_default;
 	case NFP_FLOWER_CMSG_TYPE_NO_NEIGH:
 		nfp_tunnel_request_route(app, skb);

drivers/net/ethernet/netronome/nfp/flower/cmsg.h

@@ -452,6 +452,16 @@ struct nfp_flower_cmsg_portreify {
 
 #define NFP_FLOWER_CMSG_PORTREIFY_INFO_EXIST	BIT(0)
 
+/* NFP_FLOWER_CMSG_TYPE_FLOW_MERGE_HINT */
+struct nfp_flower_cmsg_merge_hint {
+	u8 reserved[3];
+	u8 count;
+	struct {
+		__be32 host_ctx;
+		__be64 host_cookie;
+	} __packed flow[0];
+};
+
 enum nfp_flower_cmsg_port_type {
 	NFP_FLOWER_CMSG_PORT_TYPE_UNSPEC =	0x0,
 	NFP_FLOWER_CMSG_PORT_TYPE_PHYS_PORT =	0x1,

drivers/net/ethernet/netronome/nfp/flower/main.h

@@ -285,6 +285,9 @@ void nfp_flower_metadata_cleanup(struct nfp_app *app);
 
 int nfp_flower_setup_tc(struct nfp_app *app, struct net_device *netdev,
 			enum tc_setup_type type, void *type_data);
+int nfp_flower_merge_offloaded_flows(struct nfp_app *app,
+				     struct nfp_fl_payload *sub_flow1,
+				     struct nfp_fl_payload *sub_flow2);
 int nfp_flower_compile_flow_match(struct nfp_app *app,
 				  struct tc_cls_flower_offload *flow,
 				  struct nfp_fl_key_ls *key_ls,

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

@@ -388,6 +388,24 @@ nfp_flower_allocate_new(struct nfp_fl_key_ls *key_layer)
 	return NULL;
 }
 
+/**
+ * nfp_flower_merge_offloaded_flows() - Merge 2 existing flows to single flow.
+ * @app:	Pointer to the APP handle
+ * @sub_flow1:	Initial flow matched to produce merge hint
+ * @sub_flow2:	Post recirculation flow matched in merge hint
+ *
+ * Combines 2 flows (if valid) to a single flow, removing the initial from hw
+ * and offloading the new, merged flow.
+ *
+ * Return: negative value on error, 0 in success.
+ */
+int nfp_flower_merge_offloaded_flows(struct nfp_app *app,
+				     struct nfp_fl_payload *sub_flow1,
+				     struct nfp_fl_payload *sub_flow2)
+{
+	return -EOPNOTSUPP;
+}
+
 /**
  * nfp_flower_add_offload() - Adds a new flow to hardware.
  * @app:	Pointer to the APP handle