IB/core: Use GRH when the path hop-limit > 0

commit 11d8d645 upstream.

According to IBTA spec v1.3 section 12.7.19, QPs should use GRH when
the path returned by the SA has hop-limit > 0. Currently, we do that
only for the > 1 case, fix that.

Fixes: 6d969a47 ('IB/sa: Add ib_init_ah_from_path()')
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
[ kamal: backport to 4.2-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/infiniband/core/sa_query.c

@@ -542,7 +542,7 @@ int ib_init_ah_from_path(struct ib_device *device, u8 port_num,
 
 	force_grh = rdma_cap_eth_ah(device, port_num);
 
-	if (rec->hop_limit > 1 || force_grh) {
+	if (rec->hop_limit > 0 || force_grh) {
 		ah_attr->ah_flags = IB_AH_GRH;
 		ah_attr->grh.dgid = rec->dgid;