net/mlx4_core: Prevent VF from changing port configuration

Added wrapper to the ACCESS_REG command for handling guest HW
registers access, preventing write operations, but do allow reads.

This will prevent SRIOV guests to change port PTYS configuration,
such as speed/advertised link modes.

Fixes: adbc7ac5c15e ('net/mlx4_core: Introduce ACCESS_REG CMD [...]')
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -1345,7 +1345,7 @@ static struct mlx4_cmd_info cmd_info[] = {
 		.out_is_imm = false,
 		.encode_slave_id = false,
 		.verify = NULL,
-		.wrapper = NULL,
+		.wrapper = mlx4_ACCESS_REG_wrapper,
 	},
 	/* Native multicast commands are not available for guests */
 	{

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

@@ -2220,7 +2220,7 @@ static int mlx4_ACCESS_REG(struct mlx4_dev *dev, u16 reg_id,
 	memcpy(inbuf->reg_data, reg_data, reg_len);
 	err = mlx4_cmd_box(dev, inbox->dma, outbox->dma, 0, 0,
 			   MLX4_CMD_ACCESS_REG, MLX4_CMD_TIME_CLASS_C,
-			   MLX4_CMD_NATIVE);
+			   MLX4_CMD_WRAPPED);
 	if (err)
 		goto out;
 
@@ -2263,3 +2263,31 @@ int mlx4_ACCESS_PTYS_REG(struct mlx4_dev *dev,
 			       method, sizeof(*ptys_reg), ptys_reg);
 }
 EXPORT_SYMBOL_GPL(mlx4_ACCESS_PTYS_REG);
+
+int mlx4_ACCESS_REG_wrapper(struct mlx4_dev *dev, int slave,
+			    struct mlx4_vhcr *vhcr,
+			    struct mlx4_cmd_mailbox *inbox,
+			    struct mlx4_cmd_mailbox *outbox,
+			    struct mlx4_cmd_info *cmd)
+{
+	struct mlx4_access_reg *inbuf = inbox->buf;
+	u8 method = inbuf->method & MLX4_ACCESS_REG_METHOD_MASK;
+	u16 reg_id = be16_to_cpu(inbuf->reg_id);
+
+	if (slave != mlx4_master_func_num(dev) &&
+	    method == MLX4_ACCESS_REG_WRITE)
+		return -EPERM;
+
+	if (reg_id == MLX4_REG_ID_PTYS) {
+		struct mlx4_ptys_reg *ptys_reg =
+			(struct mlx4_ptys_reg *)inbuf->reg_data;
+
+		ptys_reg->local_port =
+			mlx4_slave_convert_port(dev, slave,
+						ptys_reg->local_port);
+	}
+
+	return mlx4_cmd_box(dev, inbox->dma, outbox->dma, vhcr->in_modifier,
+			    0, MLX4_CMD_ACCESS_REG, MLX4_CMD_TIME_CLASS_C,
+			    MLX4_CMD_NATIVE);
+}

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

@@ -1273,6 +1273,11 @@ int mlx4_QP_FLOW_STEERING_DETACH_wrapper(struct mlx4_dev *dev, int slave,
 					 struct mlx4_cmd_mailbox *inbox,
 					 struct mlx4_cmd_mailbox *outbox,
 					 struct mlx4_cmd_info *cmd);
+int mlx4_ACCESS_REG_wrapper(struct mlx4_dev *dev, int slave,
+			    struct mlx4_vhcr *vhcr,
+			    struct mlx4_cmd_mailbox *inbox,
+			    struct mlx4_cmd_mailbox *outbox,
+			    struct mlx4_cmd_info *cmd);
 
 int mlx4_get_mgm_entry_size(struct mlx4_dev *dev);
 int mlx4_get_qp_per_mgm(struct mlx4_dev *dev);