net: openvswitch: Set OvS recirc_id from tc chain index

Offloaded OvS datapath rules are translated one to one to tc rules,
for example the following simplified OvS rule:

recirc_id(0),in_port(dev1),eth_type(0x0800),ct_state(-trk) actions:ct(),recirc(2)

Will be translated to the following tc rule:

$ tc filter add dev dev1 ingress \
	    prio 1 chain 0 proto ip \
		flower tcp ct_state -trk \
		action ct pipe \
		action goto chain 2

Received packets will first travel though tc, and if they aren't stolen
by it, like in the above rule, they will continue to OvS datapath.
Since we already did some actions (action ct in this case) which might
modify the packets, and updated action stats, we would like to continue
the proccessing with the correct recirc_id in OvS (here recirc_id(2))
where we left off.

To support this, introduce a new skb extension for tc, which
will be used for translating tc chain to ovs recirc_id to
handle these miss cases. Last tc chain index will be set
by tc goto chain action and read by OvS datapath.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 48 insertions, 5 deletions

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 65122bbccd27..dde9d762edee 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1545,10 +1545,34 @@ static void ovs_dp_reset_user_features(struct sk_buff *skb, struct genl_info *in
 	dp->user_features = 0;
 }
 
-static void ovs_dp_change(struct datapath *dp, struct nlattr *a[])
+DEFINE_STATIC_KEY_FALSE(tc_recirc_sharing_support);
+
+static int ovs_dp_change(struct datapath *dp, struct nlattr *a[])
 {
-	if (a[OVS_DP_ATTR_USER_FEATURES])
-		dp->user_features = nla_get_u32(a[OVS_DP_ATTR_USER_FEATURES]);
+	u32 user_features = 0;
+
+	if (a[OVS_DP_ATTR_USER_FEATURES]) {
+		user_features = nla_get_u32(a[OVS_DP_ATTR_USER_FEATURES]);
+
+		if (user_features & ~(OVS_DP_F_VPORT_PIDS |
+				      OVS_DP_F_UNALIGNED |
+				      OVS_DP_F_TC_RECIRC_SHARING))
+			return -EOPNOTSUPP;
+
+#if !IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
+		if (user_features & OVS_DP_F_TC_RECIRC_SHARING)
+			return -EOPNOTSUPP;
+#endif
+	}
+
+	dp->user_features = user_features;
+
+	if (dp->user_features & OVS_DP_F_TC_RECIRC_SHARING)
+		static_branch_enable(&tc_recirc_sharing_support);
+	else
+		static_branch_disable(&tc_recirc_sharing_support);
+
+	return 0;
 }
 
 static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
@@ -1610,7 +1634,9 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	parms.port_no = OVSP_LOCAL;
 	parms.upcall_portids = a[OVS_DP_ATTR_UPCALL_PID];
 
-	ovs_dp_change(dp, a);
+	err = ovs_dp_change(dp, a);
+	if (err)
+		goto err_destroy_meters;
 
 	/* So far only local changes have been made, now need the lock. */
 	ovs_lock();
@@ -1736,7 +1762,9 @@ static int ovs_dp_cmd_set(struct sk_buff *skb, struct genl_info *info)
 	if (IS_ERR(dp))
 		goto err_unlock_free;
 
-	ovs_dp_change(dp, info->attrs);
+	err = ovs_dp_change(dp, info->attrs);
+	if (err)
+		goto err_unlock_free;
 
 	err = ovs_dp_cmd_fill_info(dp, reply, info->snd_portid,
 				   info->snd_seq, 0, OVS_DP_CMD_SET);
diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
index 751d34accdf9..81e85dde8217 100644
--- a/net/openvswitch/datapath.h
+++ b/net/openvswitch/datapath.h
@@ -218,6 +218,8 @@ static inline struct datapath *get_dp(struct net *net, int dp_ifindex)
 extern struct notifier_block ovs_dp_device_notifier;
 extern struct genl_family dp_vport_genl_family;
 
+DECLARE_STATIC_KEY_FALSE(tc_recirc_sharing_support);
+
 void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key);
 void ovs_dp_detach_port(struct vport *);
 int ovs_dp_upcall(struct datapath *, struct sk_buff *,
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 9d81d2c7bf82..38147e6a20f5 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -842,6 +842,9 @@ static int key_extract_mac_proto(struct sk_buff *skb)
 int ovs_flow_key_extract(const struct ip_tunnel_info *tun_info,
 			 struct sk_buff *skb, struct sw_flow_key *key)
 {
+#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
+	struct tc_skb_ext *tc_ext;
+#endif
 	int res, err;
 
 	/* Extract metadata from packet. */
@@ -874,7 +877,17 @@ int ovs_flow_key_extract(const struct ip_tunnel_info *tun_info,
 	if (res < 0)
 		return res;
 	key->mac_proto = res;
+
+#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
+	if (static_branch_unlikely(&tc_recirc_sharing_support)) {
+		tc_ext = skb_ext_find(skb, TC_SKB_EXT);
+		key->recirc_id = tc_ext ? tc_ext->chain : 0;
+	} else {
+		key->recirc_id = 0;
+	}
+#else
 	key->recirc_id = 0;
+#endif
 
 	err = key_extract(skb, key);
 	if (!err)