IB/mlx4: Forbid using sysfs to change RoCE pkeys

commit 2b135db3 upstream.

The pkey mapping for RoCE must remain the default mapping:
VFs:
  virtual index 0 = mapped to real index 0 (0xFFFF)
  All others indices: mapped to a real pkey index containing an
                      invalid pkey.
PF:
  virtual index i = real index i.

Don't allow users to change these mappings using files found in
sysfs.

Fixes: c1e7e466 ('IB/mlx4: Add iov directory in sysfs under the ib device')
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/infiniband/hw/mlx4/sysfs.c

@@ -660,6 +660,8 @@ static int add_port(struct mlx4_ib_dev *dev, int port_num, int slave)
 	struct mlx4_port *p;
 	int i;
 	int ret;
+	int is_eth = rdma_port_get_link_layer(&dev->ib_dev, port_num) ==
+			IB_LINK_LAYER_ETHERNET;
 
 	p = kzalloc(sizeof *p, GFP_KERNEL);
 	if (!p)
@@ -677,7 +679,8 @@ static int add_port(struct mlx4_ib_dev *dev, int port_num, int slave)
 
 	p->pkey_group.name  = "pkey_idx";
 	p->pkey_group.attrs =
-		alloc_group_attrs(show_port_pkey, store_port_pkey,
+		alloc_group_attrs(show_port_pkey,
+				  is_eth ? NULL : store_port_pkey,
 				  dev->dev->caps.pkey_table_len[port_num]);
 	if (!p->pkey_group.attrs) {
 		ret = -ENOMEM;