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
i915_gemfs_init(struct drm_i915_private * i915)13 int i915_gemfs_init(struct drm_i915_private *i915)
14 {
15 struct file_system_type *type;
16 struct vfsmount *gemfs;
17 char *opts;
18
19 type = get_fs_type("tmpfs");
20 if (!type)
21 return -ENODEV;
22
23 /*
24 * By creating our own shmemfs mountpoint, we can pass in
25 * mount flags that better match our usecase.
26 *
27 * One example, although it is probably better with a per-file
28 * control, is selecting huge page allocations ("huge=within_size").
29 * However, we only do so to offset the overhead of iommu lookups
30 * due to bandwidth issues (slow reads) on Broadwell+.
31 */
32
33 opts = NULL;
34 if (intel_vtd_active()) {
35 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
36 static char huge_opt[] = "huge=within_size"; /* r/w */
37
38 opts = huge_opt;
39 drm_info(&i915->drm,
40 "Transparent Hugepage mode '%s'\n",
41 opts);
42 } else {
43 drm_notice(&i915->drm,
44 "Transparent Hugepage support is recommended for optimal performance when IOMMU is enabled!\n");
45 }
46 }
47
48 gemfs = vfs_kern_mount(type, SB_KERNMOUNT, type->name, opts);
49 if (IS_ERR(gemfs))
50 return PTR_ERR(gemfs);
51
52 i915->mm.gemfs = gemfs;
53
54 return 0;
55 }
56
i915_gemfs_fini(struct drm_i915_private * i915)57 void i915_gemfs_fini(struct drm_i915_private *i915)
58 {
59 kern_unmount(i915->mm.gemfs);
60 }
61