IB/mlx5: Add MR cache for large UMR regions

In this change we turn mlx5_ib_update_mtt() into generic
mlx5_ib_update_xlt() to perfrom HCA translation table modifiactions
supporting both atomic and process contexts and not limited by number
of modified entries.
Using this function we increase preallocated MRs up to 16GB.

Signed-off-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/infiniband/hw/mlx5/main.c

@@ -1112,11 +1112,18 @@ static struct ib_ucontext *mlx5_ib_alloc_ucontext(struct ib_device *ibdev,
 	context->ibucontext.invalidate_range = &mlx5_ib_invalidate_range;
 #endif
 
+	context->upd_xlt_page = __get_free_page(GFP_KERNEL);
+	if (!context->upd_xlt_page) {
+		err = -ENOMEM;
+		goto out_uars;
+	}
+	mutex_init(&context->upd_xlt_page_mutex);
+
 	if (MLX5_CAP_GEN(dev->mdev, log_max_transport_domain)) {
 		err = mlx5_core_alloc_transport_domain(dev->mdev,
 						       &context->tdn);
 		if (err)
-			goto out_uars;
+			goto out_page;
 	}
 
 	INIT_LIST_HEAD(&context->vma_private_list);
@@ -1168,6 +1175,9 @@ out_td:
 	if (MLX5_CAP_GEN(dev->mdev, log_max_transport_domain))
 		mlx5_core_dealloc_transport_domain(dev->mdev, context->tdn);
 
+out_page:
+	free_page(context->upd_xlt_page);
+
 out_uars:
 	for (i--; i >= 0; i--)
 		mlx5_cmd_free_uar(dev->mdev, uars[i].index);
@@ -1195,6 +1205,8 @@ static int mlx5_ib_dealloc_ucontext(struct ib_ucontext *ibcontext)
 	if (MLX5_CAP_GEN(dev->mdev, log_max_transport_domain))
 		mlx5_core_dealloc_transport_domain(dev->mdev, context->tdn);
 
+	free_page(context->upd_xlt_page);
+
 	for (i = 0; i < uuari->num_uars; i++) {
 		if (mlx5_cmd_free_uar(dev->mdev, uuari->uars[i].index))
 			mlx5_ib_warn(dev, "failed to free UAR 0x%x\n", uuari->uars[i].index);