1/*
2 * SPDX-License-Identifier: MIT
3 *
4 * Copyright �� 2017 Intel Corporation
5 */
6
7#include <linux/fs.h>
8#include <linux/mount.h>
9
10#include "i915_drv.h"
11#include "i915_gemfs.h"
12#include "i915_utils.h"
13
14void i915_gemfs_init(struct drm_i915_private *i915)
15{
16	char huge_opt[] = "huge=within_size"; /* r/w */
17	struct file_system_type *type;
18	struct vfsmount *gemfs;
19
20	/*
21	 * By creating our own shmemfs mountpoint, we can pass in
22	 * mount flags that better match our usecase.
23	 *
24	 * One example, although it is probably better with a per-file
25	 * control, is selecting huge page allocations ("huge=within_size").
26	 * However, we only do so on platforms which benefit from it, or to
27	 * offset the overhead of iommu lookups, where with latter it is a net
28	 * win even on platforms which would otherwise see some performance
29	 * regressions such a slow reads issue on Broadwell and Skylake.
30	 */
31
32	if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
33		return;
34
35	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
36		goto err;
37
38	type = get_fs_type("tmpfs");
39	if (!type)
40		goto err;
41
42	gemfs = vfs_kern_mount(type, SB_KERNMOUNT, type->name, huge_opt);
43	if (IS_ERR(gemfs))
44		goto err;
45
46	i915->mm.gemfs = gemfs;
47	drm_info(&i915->drm, "Using Transparent Hugepages\n");
48	return;
49
50err:
51	drm_notice(&i915->drm,
52		   "Transparent Hugepage support is recommended for optimal performance%s\n",
53		   GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
54					      " when IOMMU is enabled!");
55}
56
57void i915_gemfs_fini(struct drm_i915_private *i915)
58{
59	kern_unmount(i915->mm.gemfs);
60}
61