net: ethernet: mtk_ppe_offload: Allow QinQ, double ETH_P_8021Q only

[ Upstream commit 7fe0353 ]

mtk_foe_entry_set_vlan() in mtk_ppe.c already supports double vlan
tagging, but mtk_flow_offload_replace() in mtk_ppe_offload.c only allows
for 1 vlan tag, optionally in combination with pppoe and dsa tags.

However, mtk_foe_entry_set_vlan() only allows for setting the vlan id.
The protocol cannot be set, it is always ETH_P_8021Q, for inner and outer
tag. This patch adds QinQ support to mtk_flow_offload_replace(), only in
the case that both inner and outer tags are ETH_P_8021Q.

Only PPPoE-in-Q (as before) and Q-in-Q are allowed. A combination
of PPPoE and Q-in-Q is not allowed.

Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
Link: https://patch.msgid.link/20250225201509.20843-1-ericwouds@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 7b8fe48cc86b6c71e337bd178b98b59ba3d115b0)

Author: ericwoud

drivers/net/ethernet/mediatek/mtk_ppe_offload.c

@@ -34,8 +34,10 @@ struct mtk_flow_data {
 	u16 vlan_in;
 
 	struct {
-		u16 id;
-		__be16 proto;
+		struct {
+			u16 id;
+			__be16 proto;
+		} vlans[2];
 		u8 num;
 	} vlan;
 	struct {
@@ -330,18 +332,19 @@ mtk_flow_offload_replace(struct mtk_eth *eth, struct flow_cls_offload *f,
 		case FLOW_ACTION_CSUM:
 			break;
 		case FLOW_ACTION_VLAN_PUSH:
-			if (data.vlan.num == 1 ||
+			if (data.vlan.num + data.pppoe.num == 2 ||
 			    act->vlan.proto != htons(ETH_P_8021Q))
 				return -EOPNOTSUPP;
 
-			data.vlan.id = act->vlan.vid;
-			data.vlan.proto = act->vlan.proto;
+			data.vlan.vlans[data.vlan.num].id = act->vlan.vid;
+			data.vlan.vlans[data.vlan.num].proto = act->vlan.proto;
 			data.vlan.num++;
 			break;
 		case FLOW_ACTION_VLAN_POP:
 			break;
 		case FLOW_ACTION_PPPOE_PUSH:
-			if (data.pppoe.num == 1)
+			if (data.pppoe.num == 1 ||
+			    data.vlan.num == 2)
 				return -EOPNOTSUPP;
 
 			data.pppoe.sid = act->pppoe.sid;
@@ -431,12 +434,9 @@ mtk_flow_offload_replace(struct mtk_eth *eth, struct flow_cls_offload *f,
 	if (offload_type == MTK_PPE_PKT_TYPE_BRIDGE)
 		foe.bridge.vlan = data.vlan_in;
 
-	if (data.vlan.num == 1) {
-		if (data.vlan.proto != htons(ETH_P_8021Q))
-			return -EOPNOTSUPP;
+	for (i = 0; i < data.vlan.num; i++)
+		mtk_foe_entry_set_vlan(eth, &foe, data.vlan.vlans[i].id);
 
-		mtk_foe_entry_set_vlan(eth, &foe, data.vlan.id);
-	}
 	if (data.pppoe.num == 1)
 		mtk_foe_entry_set_pppoe(eth, &foe, data.pppoe.sid);