IB/mlx5: Add ODP support to MW

Internally MW implemented as KLM MKey and filled by userspace UMR
postsends.  Handle pagefault trigered by operations on this MKeys.

Signed-off-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 191b82b..93c6466 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -513,6 +513,7 @@ struct mlx5_ib_mr {
 struct mlx5_ib_mw {
 	struct ib_mw		ibmw;
 	struct mlx5_core_mkey	mmkey;
+	int			ndescs;
 };
 
 struct mlx5_ib_umr_context {