sfc: support offloading ct(nat) action in RHS rules

If an IP address and/or L4 port for NAPT is available from a CT match,
the MAE will perform the edits; if no CT lookup has been performed for
this packet, the CT lookup did not return a match, or the matched CT
entry did not include NAPT, the action will have no effect.

Reviewed-by: Pieter Jansen van Vuuren <[e-mail]>
Signed-off-by: Edward Cree <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/sfc/mae.c

···
 	size_t outlen;
 	int rc;
 
-	MCDI_POPULATE_DWORD_4(inbuf, MAE_ACTION_SET_ALLOC_IN_FLAGS,
+	MCDI_POPULATE_DWORD_5(inbuf, MAE_ACTION_SET_ALLOC_IN_FLAGS,
 			      MAE_ACTION_SET_ALLOC_IN_VLAN_PUSH, act->vlan_push,
 			      MAE_ACTION_SET_ALLOC_IN_VLAN_POP, act->vlan_pop,
 			      MAE_ACTION_SET_ALLOC_IN_DECAP, act->decap,
+			      MAE_ACTION_SET_ALLOC_IN_DO_NAT, act->do_nat,
 			      MAE_ACTION_SET_ALLOC_IN_DO_DECR_IP_TTL,
 			      act->do_ttl_dec);
 

drivers/net/ethernet/sfc/tc.c

···
 			NL_SET_ERR_MSG_MOD(extack, "Cannot offload tunnel decap action without tunnel device");
 			rc = -EOPNOTSUPP;
 			goto release;
+		case FLOW_ACTION_CT:
+			if (fa->ct.action != TCA_CT_ACT_NAT) {
+				rc = -EOPNOTSUPP;
+				NL_SET_ERR_MSG_FMT_MOD(extack, "Can only offload CT 'nat' action in RHS rules, not %d", fa->ct.action);
+				goto release;
+			}
+			act->do_nat = 1;
+			break;
 		default:
 			NL_SET_ERR_MSG_FMT_MOD(extack, "Unhandled action %u",
 					       fa->id);

drivers/net/ethernet/sfc/tc.h

···
  * @vlan_push: the number of vlan headers to push
  * @vlan_pop: the number of vlan headers to pop
  * @decap: used to indicate a tunnel header decapsulation should take place
+ * @do_nat: perform NAT/NPT with values returned by conntrack match
  * @do_ttl_dec: used to indicate IP TTL / Hop Limit should be decremented
  * @deliver: used to indicate a deliver action should take place
  * @vlan_tci: tci fields for vlan push actions
···
 	u16 vlan_push:2;
 	u16 vlan_pop:2;
 	u16 decap:1;
+	u16 do_nat:1;
 	u16 do_ttl_dec:1;
 	u16 deliver:1;
 	__be16 vlan_tci[2];