diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 270c7ff6cba7..10979844026a 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -650,10 +650,23 @@ int ib_query_port(struct ib_device *device,
 		  u8 port_num,
 		  struct ib_port_attr *port_attr)
 {
+	union ib_gid gid;
+	int err;
+
 	if (port_num < rdma_start_port(device) || port_num > rdma_end_port(device))
 		return -EINVAL;
 
-	return device->query_port(device, port_num, port_attr);
+	memset(port_attr, 0, sizeof(*port_attr));
+	err = device->query_port(device, port_num, port_attr);
+	if (err || port_attr->subnet_prefix)
+		return err;
+
+	err = ib_query_gid(device, port_num, 0, &gid, NULL);
+	if (err)
+		return err;
+
+	port_attr->subnet_prefix = be64_to_cpu(gid.global.subnet_prefix);
+	return 0;
 }
 EXPORT_SYMBOL(ib_query_port);
 
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index c9b62344d22e..7239b9a4499e 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -490,6 +490,7 @@ union rdma_protocol_stats {
 					| RDMA_CORE_CAP_OPA_MAD)
 
 struct ib_port_attr {
+	u64			subnet_prefix;
 	enum ib_port_state	state;
 	enum ib_mtu		max_mtu;
 	enum ib_mtu		active_mtu;