net: cls_bpf: add support for marking filters as hardware-only

Add cls_bpf support for the TCA_CLS_FLAGS_SKIP_SW flag.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_bpf.c

@@ -28,7 +28,7 @@ MODULE_DESCRIPTION("TC BPF based classifier");
 
 #define CLS_BPF_NAME_LEN	256
 #define CLS_BPF_SUPPORTED_GEN_FLAGS		\
-	TCA_CLS_FLAGS_SKIP_HW
+	(TCA_CLS_FLAGS_SKIP_HW | TCA_CLS_FLAGS_SKIP_SW)
 
 struct cls_bpf_head {
 	struct list_head plist;
@@ -96,7 +96,9 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 
 		qdisc_skb_cb(skb)->tc_classid = prog->res.classid;
 
-		if (at_ingress) {
+		if (tc_skip_sw(prog->gen_flags)) {
+			filter_res = prog->exts_integrated ? TC_ACT_UNSPEC : 0;
+		} else if (at_ingress) {
 			/* It is safe to push/pull even if skb_shared() */
 			__skb_push(skb, skb->mac_len);
 			bpf_compute_data_end(skb);
@@ -164,32 +166,42 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog,
 					     tp->protocol, &offload);
 }
 
-static void cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog,
-			    struct cls_bpf_prog *oldprog)
+static int cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog,
+			   struct cls_bpf_prog *oldprog)
 {
 	struct net_device *dev = tp->q->dev_queue->dev;
 	struct cls_bpf_prog *obj = prog;
 	enum tc_clsbpf_command cmd;
+	bool skip_sw;
+	int ret;
+
+	skip_sw = tc_skip_sw(prog->gen_flags) ||
+		(oldprog && tc_skip_sw(oldprog->gen_flags));
 
 	if (oldprog && oldprog->offloaded) {
 		if (tc_should_offload(dev, tp, prog->gen_flags)) {
 			cmd = TC_CLSBPF_REPLACE;
-		} else {
+		} else if (!tc_skip_sw(prog->gen_flags)) {
 			obj = oldprog;
 			cmd = TC_CLSBPF_DESTROY;
+		} else {
+			return -EINVAL;
 		}
 	} else {
 		if (!tc_should_offload(dev, tp, prog->gen_flags))
-			return;
+			return skip_sw ? -EINVAL : 0;
 		cmd = TC_CLSBPF_ADD;
 	}
 
-	if (cls_bpf_offload_cmd(tp, obj, cmd))
-		return;
+	ret = cls_bpf_offload_cmd(tp, obj, cmd);
+	if (ret)
+		return skip_sw ? ret : 0;
 
 	obj->offloaded = true;
 	if (oldprog)
 		oldprog->offloaded = false;
+
+	return 0;
 }
 
 static void cls_bpf_stop_offload(struct tcf_proto *tp,
@@ -498,7 +510,11 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
 	if (ret < 0)
 		goto errout;
 
-	cls_bpf_offload(tp, prog, oldprog);
+	ret = cls_bpf_offload(tp, prog, oldprog);
+	if (ret) {
+		cls_bpf_delete_prog(tp, prog);
+		return ret;
+	}
 
 	if (oldprog) {
 		list_replace_rcu(&oldprog->link, &prog->link);