RDMA/mlx5: Fix definition of mlx5_ib_create_qp_resp

This structure is pushed down the ex and the non-ex path, so it needs to be
aligned to 8 bytes to go through ex without implicit padding.

Old user space will provide 4 bytes of resp on !ex and 8 bytes on ex, so
take the approach of just copying the minimum length.

New user space will consistently provide 8 bytes in both cases.
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/qp.c

@@ -880,7 +880,7 @@ static int create_user_qp(struct mlx5_ib_dev *dev, struct ib_pd *pd,
 		goto err_free;
 	}
 
-	err = ib_copy_to_udata(udata, resp, sizeof(*resp));
+	err = ib_copy_to_udata(udata, resp, min(udata->outlen, sizeof(*resp)));
 	if (err) {
 		mlx5_ib_dbg(dev, "copy failed\n");
 		goto err_unmap;
@@ -1468,7 +1468,7 @@ static int create_rss_raw_qp_tir(struct mlx5_ib_dev *dev, struct mlx5_ib_qp *qp,
 		return -EOPNOTSUPP;
 	}
 
-	err = ib_copy_to_udata(udata, &resp, min_resp_len);
+	err = ib_copy_to_udata(udata, &resp, min(udata->outlen, sizeof(resp)));
 	if (err) {
 		mlx5_ib_dbg(dev, "copy failed\n");
 		return -EINVAL;

include/uapi/rdma/mlx5-abi.h

@@ -335,6 +335,7 @@ struct mlx5_ib_create_qp_rss {
 
 struct mlx5_ib_create_qp_resp {
 	__u32	bfreg_index;
+	__u32   reserved;
 };
 
 struct mlx5_ib_alloc_mw {