drm/i915: Use huge tmpfs mountpoint helpers

Make use of the new drm_gem_huge_mnt_create() and
drm_gem_get_huge_mnt() helpers to avoid code duplication. Now that
it's just a few lines long, the single function in i915_gemfs.c is
moved into i915_gem_shmem.c.

v3:
- use huge tmpfs mountpoint in drm_device
- move i915_gemfs.c into i915_gem_shmem.c

v4:
- clean up mountpoint creation error handling

v5:
- use drm_gem_has_huge_mnt() helper

v7:
- include <drm/drm_print.h> in i915_gem_shmem.c

v8:
- keep logging notice message with CONFIG_TRANSPARENT_HUGEPAGE=n
- don't access huge_mnt field with CONFIG_TRANSPARENT_HUGEPAGE=n

v9:
- replace drm_gem_has_huge_mnt() by drm_gem_get_huge_mnt()
- remove useless ternary op test in selftests/huge_pages.c

v12:
- fix layering violation in selftests (Tvrtko)
- fix incorrect filename in commit message

v13:
- add Tvrtko A-b

Signed-off-by: Loïc Molinari <loic.molinari@collabora.com>
Acked-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://patch.msgid.link/20251205182231.194072-6-loic.molinari@collabora.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

drivers/gpu/drm/i915/Makefile

@@ -169,8 +169,7 @@ gem-y += \
 	gem/i915_gem_ttm_move.o \
 	gem/i915_gem_ttm_pm.o \
 	gem/i915_gem_userptr.o \
-	gem/i915_gem_wait.o \
+	gem/i915_gem_wait.o
-	gem/i915_gemfs.o
 i915-y += \
 	$(gem-y) \
 	i915_active.o \

drivers/gpu/drm/i915/gem/i915_gem_object_types.h

@@ -348,12 +348,13 @@ struct drm_i915_gem_object {
  */
 #define I915_BO_ALLOC_GPU_ONLY	  BIT(6)
 #define I915_BO_ALLOC_CCS_AUX	  BIT(7)
+#define I915_BO_ALLOC_NOTHP	  BIT(8)
 /*
  * Object is allowed to retain its initial data and will not be cleared on first
  * access if used along with I915_BO_ALLOC_USER. This is mainly to keep
  * preallocated framebuffer data intact while transitioning it to i915drmfb.
  */
-#define I915_BO_PREALLOC	  BIT(8)
+#define I915_BO_PREALLOC	  BIT(9)
 #define I915_BO_ALLOC_FLAGS (I915_BO_ALLOC_CONTIGUOUS | \
 			     I915_BO_ALLOC_VOLATILE | \
 			     I915_BO_ALLOC_CPU_CLEAR | \
@@ -363,9 +364,9 @@ struct drm_i915_gem_object {
 			     I915_BO_ALLOC_GPU_ONLY | \
 			     I915_BO_ALLOC_CCS_AUX | \
 			     I915_BO_PREALLOC)
-#define I915_BO_READONLY          BIT(9)
+#define I915_BO_READONLY          BIT(10)
-#define I915_TILING_QUIRK_BIT     10 /* unknown swizzling; do not release! */
+#define I915_TILING_QUIRK_BIT     11 /* unknown swizzling; do not release! */
-#define I915_BO_PROTECTED         BIT(11)
+#define I915_BO_PROTECTED         BIT(12)
 	/**
 	 * @mem_flags - Mutable placement-related flags
 	 *

drivers/gpu/drm/i915/gem/i915_gem_shmem.c

@@ -9,14 +9,16 @@
 #include <linux/uio.h>
 
 #include <drm/drm_cache.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_print.h>
 
 #include "gem/i915_gem_region.h"
 #include "i915_drv.h"
 #include "i915_gem_object.h"
 #include "i915_gem_tiling.h"
-#include "i915_gemfs.h"
 #include "i915_scatterlist.h"
 #include "i915_trace.h"
+#include "i915_utils.h"
 
 /*
  * Move folios to appropriate lru and release the batch, decrementing the
@@ -494,9 +496,11 @@ const struct drm_i915_gem_object_ops i915_gem_shmem_ops = {
 
 static int __create_shmem(struct drm_i915_private *i915,
 			  struct drm_gem_object *obj,
-			  resource_size_t size)
+			  resource_size_t size,
+			  unsigned int flags)
 {
-	unsigned long flags = VM_NORESERVE;
+	unsigned long shmem_flags = VM_NORESERVE;
+	struct vfsmount *huge_mnt;
 	struct file *filp;
 
 	drm_gem_private_object_init(&i915->drm, obj, size);
@@ -515,11 +519,12 @@ static int __create_shmem(struct drm_i915_private *i915,
 	if (BITS_PER_LONG == 64 && size > MAX_LFS_FILESIZE)
 		return -E2BIG;
 
-	if (i915->mm.gemfs)
+	huge_mnt = drm_gem_get_huge_mnt(&i915->drm);
-		filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size,
+	if (!(flags & I915_BO_ALLOC_NOTHP) && huge_mnt)
-						 flags);
+		filp = shmem_file_setup_with_mnt(huge_mnt, "i915", size,
+						 shmem_flags);
 	else
-		filp = shmem_file_setup("i915", size, flags);
+		filp = shmem_file_setup("i915", size, shmem_flags);
 	if (IS_ERR(filp))
 		return PTR_ERR(filp);
 
@@ -548,7 +553,7 @@ static int shmem_object_init(struct intel_memory_region *mem,
 	gfp_t mask;
 	int ret;
 
-	ret = __create_shmem(i915, &obj->base, size);
+	ret = __create_shmem(i915, &obj->base, size, flags);
 	if (ret)
 		return ret;
 
@@ -644,21 +649,40 @@ i915_gem_object_create_shmem_from_data(struct drm_i915_private *i915,
 
 static int init_shmem(struct intel_memory_region *mem)
 {
-	i915_gemfs_init(mem->i915);
+	struct drm_i915_private *i915 = mem->i915;
+
+	/*
+	 * By creating our own shmemfs mountpoint, we can pass in
+	 * mount flags that better match our usecase.
+	 *
+	 * One example, although it is probably better with a per-file
+	 * control, is selecting huge page allocations ("huge=within_size").
+	 * However, we only do so on platforms which benefit from it, or to
+	 * offset the overhead of iommu lookups, where with latter it is a net
+	 * win even on platforms which would otherwise see some performance
+	 * regressions such a slow reads issue on Broadwell and Skylake.
+	 */
+
+	if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
+		goto no_thp;
+
+	drm_gem_huge_mnt_create(&i915->drm, "within_size");
+	if (drm_gem_get_huge_mnt(&i915->drm))
+		drm_info(&i915->drm, "Using Transparent Hugepages\n");
+	else
+		drm_notice(&i915->drm,
+			   "Transparent Hugepage support is recommended for optimal performance%s\n",
+			   GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
+						      " when IOMMU is enabled!");
+
+ no_thp:
 	intel_memory_region_set_name(mem, "system");
 
-	return 0; /* We have fallback to the kernel mnt if gemfs init failed. */
+	return 0; /* We have fallback to the kernel mnt if huge mnt failed. */
-}
-
-static int release_shmem(struct intel_memory_region *mem)
-{
-	i915_gemfs_fini(mem->i915);
-	return 0;
 }
 
 static const struct intel_memory_region_ops shmem_region_ops = {
 	.init = init_shmem,
-	.release = release_shmem,
 	.init_object = shmem_object_init,
 };
 

drivers/gpu/drm/i915/gem/i915_gemfs.c

@@ -1,71 +0,0 @@
-// SPDX-License-Identifier: MIT
-/*
- * Copyright © 2017 Intel Corporation
- */
-
-#include <linux/fs.h>
-#include <linux/mount.h>
-#include <linux/fs_context.h>
-
-#include <drm/drm_print.h>
-
-#include "i915_drv.h"
-#include "i915_gemfs.h"
-#include "i915_utils.h"
-
-void i915_gemfs_init(struct drm_i915_private *i915)
-{
-	struct file_system_type *type;
-	struct fs_context *fc;
-	struct vfsmount *gemfs;
-	int ret;
-
-	/*
-	 * By creating our own shmemfs mountpoint, we can pass in
-	 * mount flags that better match our usecase.
-	 *
-	 * One example, although it is probably better with a per-file
-	 * control, is selecting huge page allocations ("huge=within_size").
-	 * However, we only do so on platforms which benefit from it, or to
-	 * offset the overhead of iommu lookups, where with latter it is a net
-	 * win even on platforms which would otherwise see some performance
-	 * regressions such a slow reads issue on Broadwell and Skylake.
-	 */
-
-	if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
-		return;
-
-	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
-		goto err;
-
-	type = get_fs_type("tmpfs");
-	if (!type)
-		goto err;
-
-	fc = fs_context_for_mount(type, SB_KERNMOUNT);
-	if (IS_ERR(fc))
-		goto err;
-	ret = vfs_parse_fs_string(fc, "source", "tmpfs");
-	if (!ret)
-		ret = vfs_parse_fs_string(fc, "huge", "within_size");
-	if (!ret)
-		gemfs = fc_mount_longterm(fc);
-	put_fs_context(fc);
-	if (ret)
-		goto err;
-
-	i915->mm.gemfs = gemfs;
-	drm_info(&i915->drm, "Using Transparent Hugepages\n");
-	return;
-
-err:
-	drm_notice(&i915->drm,
-		   "Transparent Hugepage support is recommended for optimal performance%s\n",
-		   GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
-					      " when IOMMU is enabled!");
-}
-
-void i915_gemfs_fini(struct drm_i915_private *i915)
-{
-	kern_unmount(i915->mm.gemfs);
-}

drivers/gpu/drm/i915/gem/i915_gemfs.h

@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: MIT */
-/*
- * Copyright © 2017 Intel Corporation
- */
-
-#ifndef __I915_GEMFS_H__
-#define __I915_GEMFS_H__
-
-struct drm_i915_private;
-
-void i915_gemfs_init(struct drm_i915_private *i915);
-void i915_gemfs_fini(struct drm_i915_private *i915);
-
-#endif

drivers/gpu/drm/i915/gem/selftests/huge_pages.c

@@ -1316,7 +1316,7 @@ typedef struct drm_i915_gem_object *
 
 static inline bool igt_can_allocate_thp(struct drm_i915_private *i915)
 {
-	return i915->mm.gemfs && has_transparent_hugepage();
+	return !!drm_gem_get_huge_mnt(&i915->drm);
 }
 
 static struct drm_i915_gem_object *
@@ -1761,7 +1761,6 @@ static int igt_tmpfs_fallback(void *arg)
 	struct drm_i915_private *i915 = arg;
 	struct i915_address_space *vm;
 	struct i915_gem_context *ctx;
-	struct vfsmount *gemfs = i915->mm.gemfs;
 	struct drm_i915_gem_object *obj;
 	struct i915_vma *vma;
 	struct file *file;
@@ -1779,15 +1778,8 @@ static int igt_tmpfs_fallback(void *arg)
 	}
 	vm = i915_gem_context_get_eb_vm(ctx);
 
-	/*
+	obj = i915_gem_object_create_region(i915->mm.regions[INTEL_REGION_SMEM],
-	 * Make sure that we don't burst into a ball of flames upon falling back
+					    PAGE_SIZE, 0, I915_BO_ALLOC_NOTHP);
-	 * to tmpfs, which we rely on if on the off-chance we encounter a failure
-	 * when setting up gemfs.
-	 */
-
-	i915->mm.gemfs = NULL;
-
-	obj = i915_gem_object_create_shmem(i915, PAGE_SIZE);
 	if (IS_ERR(obj)) {
 		err = PTR_ERR(obj);
 		goto out_restore;
@@ -1819,7 +1811,6 @@ static int igt_tmpfs_fallback(void *arg)
 out_put:
 	i915_gem_object_put(obj);
 out_restore:
-	i915->mm.gemfs = gemfs;
 
 	i915_vm_put(vm);
 out:

drivers/gpu/drm/i915/i915_drv.h

@@ -141,11 +141,6 @@ struct i915_gem_mm {
 	 */
 	atomic_t free_count;
 
-	/**
-	 * tmpfs instance used for shmem backed objects
-	 */
-	struct vfsmount *gemfs;
-
 	struct intel_memory_region *regions[INTEL_REGION_UNKNOWN];
 
 	struct notifier_block oom_notifier;