sfc: offload foreign RHS rules without an encap match

Normally, if a TC filter on a tunnel netdev does not match on any
 encap fields, we decline to offload it, as it cannot meet our
 requirement for a <sip,dip,dport> tuple for the encap match.
However, if the rule has a nonzero chain_index, then for a packet to
 reach the rule, it must already have matched a LHS rule which will
 have included an encap match and determined the tunnel type, so in
 that case we can offload the right-hand-side rule.
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/tc.c

@@ -1683,7 +1683,7 @@ static int efx_tc_flower_replace_foreign(struct efx_nic *efx,
 						      extack);
 		if (rc)
 			goto release;
-	} else {
+	} else if (!tc->common.chain_index) {
 		/* This is not a tunnel decap rule, ignore it */
 		netif_dbg(efx, drv, efx->net_dev,
 			  "Ignoring foreign filter without encap match\n");