net/mlx4_core: Don't allow to VF change global pause settings

Currently changing global pause settings is done via SET_PORT
command with input modifier GENERAL. This command is allowed
for each VF since MTU setting is done via the same command.

Change the above to the following scheme: before passing the
request to the FW, the PF will check whether it was issued
by a slave. If yes, don't change global pause and warn,
otherwise change to the requested value and store for
further reference.
Signed-off-by: NEugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/mlx4.h

@@ -586,6 +586,8 @@ struct mlx4_mfunc_master_ctx {
 	struct mlx4_master_qp0_state qp0_state[MLX4_MAX_PORTS + 1];
 	int			init_port_ref[MLX4_MAX_PORTS + 1];
 	u16			max_mtu[MLX4_MAX_PORTS + 1];
+	u8			pptx;
+	u8			pprx;
 	int			disable_mcast_ref[MLX4_MAX_PORTS + 1];
 	struct mlx4_resource_tracker res_tracker;
 	struct workqueue_struct *comm_wq;

drivers/net/ethernet/mellanox/mlx4/port.c

@@ -1317,6 +1317,19 @@ static int mlx4_common_set_port(struct mlx4_dev *dev, int slave, u32 in_mod,
 			}
 
 			gen_context->mtu = cpu_to_be16(master->max_mtu[port]);
+			/* Slave cannot change Global Pause configuration */
+			if (slave != mlx4_master_func_num(dev) &&
+			    ((gen_context->pptx != master->pptx) ||
+			     (gen_context->pprx != master->pprx))) {
+				gen_context->pptx = master->pptx;
+				gen_context->pprx = master->pprx;
+				mlx4_warn(dev,
+					  "denying Global Pause change for slave:%d\n",
+					  slave);
+			} else {
+				master->pptx = gen_context->pptx;
+				master->pprx = gen_context->pprx;
+			}
 			break;
 		case MLX4_SET_PORT_GID_TABLE:
 			/* change to MULTIPLE entries: number of guest's gids