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
add_param(struct fs_context * fc,const char * key,const char * val)14 static int add_param(struct fs_context *fc, const char *key, const char *val)
15 {
16 return vfs_parse_fs_string(fc, key, val, strlen(val));
17 }
18
i915_gemfs_init(struct drm_i915_private * i915)19 void i915_gemfs_init(struct drm_i915_private *i915)
20 {
21 struct file_system_type *type;
22 struct fs_context *fc;
23 struct vfsmount *gemfs;
24 int ret;
25
26 /*
27 * By creating our own shmemfs mountpoint, we can pass in
28 * mount flags that better match our usecase.
29 *
30 * One example, although it is probably better with a per-file
31 * control, is selecting huge page allocations ("huge=within_size").
32 * However, we only do so on platforms which benefit from it, or to
33 * offset the overhead of iommu lookups, where with latter it is a net
34 * win even on platforms which would otherwise see some performance
35 * regressions such a slow reads issue on Broadwell and Skylake.
36 */
37
38 if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
39 return;
40
41 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
42 goto err;
43
44 type = get_fs_type("tmpfs");
45 if (!type)
46 goto err;
47
48 fc = fs_context_for_mount(type, SB_KERNMOUNT);
49 if (IS_ERR(fc))
50 goto err;
51 ret = add_param(fc, "source", "tmpfs");
52 if (!ret)
53 ret = add_param(fc, "huge", "within_size");
54 if (!ret)
55 gemfs = fc_mount_longterm(fc);
56 put_fs_context(fc);
57 if (ret)
58 goto err;
59
60 i915->mm.gemfs = gemfs;
61 drm_info(&i915->drm, "Using Transparent Hugepages\n");
62 return;
63
64 err:
65 drm_notice(&i915->drm,
66 "Transparent Hugepage support is recommended for optimal performance%s\n",
67 GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
68 " when IOMMU is enabled!");
69 }
70
i915_gemfs_fini(struct drm_i915_private * i915)71 void i915_gemfs_fini(struct drm_i915_private *i915)
72 {
73 kern_unmount(i915->mm.gemfs);
74 }
75