1// SPDX-License-Identifier: MIT
2/*
3 * Copyright © 2017 Intel Corporation
4 */
5
6#include <linux/fs.h>
7#include <linux/mount.h>
8#include <linux/fs_context.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 struct file_system_type *type;
17 struct fs_context *fc;
18 struct vfsmount *gemfs;
19 int ret;
20
21 /*
22 * By creating our own shmemfs mountpoint, we can pass in
23 * mount flags that better match our usecase.
24 *
25 * One example, although it is probably better with a per-file
26 * control, is selecting huge page allocations ("huge=within_size").
27 * However, we only do so on platforms which benefit from it, or to
28 * offset the overhead of iommu lookups, where with latter it is a net
29 * win even on platforms which would otherwise see some performance
30 * regressions such a slow reads issue on Broadwell and Skylake.
31 */
32
33 if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
34 return;
35
36 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
37 goto err;
38
39 type = get_fs_type(name: "tmpfs");
40 if (!type)
41 goto err;
42
43 fc = fs_context_for_mount(fs_type: type, SB_KERNMOUNT);
44 if (IS_ERR(ptr: fc))
45 goto err;
46 ret = vfs_parse_fs_string(fc, key: "source", value: "tmpfs");
47 if (!ret)
48 ret = vfs_parse_fs_string(fc, key: "huge", value: "within_size");
49 if (!ret)
50 gemfs = fc_mount_longterm(fc);
51 put_fs_context(fc);
52 if (ret)
53 goto err;
54
55 i915->mm.gemfs = gemfs;
56 drm_info(&i915->drm, "Using Transparent Hugepages\n");
57 return;
58
59err:
60 drm_notice(&i915->drm,
61 "Transparent Hugepage support is recommended for optimal performance%s\n",
62 GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
63 " when IOMMU is enabled!");
64}
65
66void i915_gemfs_fini(struct drm_i915_private *i915)
67{
68 kern_unmount(mnt: i915->mm.gemfs);
69}
70