Commit 6e0b1b82 authored by Loïc Molinari's avatar Loïc Molinari Committed by Boris Brezillon
Browse files

drm/gem: Add huge tmpfs mountpoint helpers 



Add the drm_gem_huge_mnt_create() and drm_gem_get_huge_mnt() helpers
to avoid code duplication in the i915, V3D, Panfrost and Panthor
drivers. The former creates and mounts a dedicated huge tmpfs
mountpoint, for the lifetime of a DRM device, used at GEM object
initialization. The latter retrieves the dedicated huge tmpfs
mountpoint used by a DRM device.

The next commits will port drivers to these helpers.

v3:
- store huge tmpfs mountpoint in drm_device

v4:
- return 0 in builds with CONFIG_TRANSPARENT_HUGEPAGE=n
- return 0 when huge_mnt already exists
- use new vfs_parse_fs_string() helper

v5:
- remove warning on !dev->huge_mnt and reset to NULL on free
- inline drm_gem_huge_mnt_create() to remove func from text and avoid
  calls in builds with CONFIG_TRANSPARENT_HUGEPAGE=n
- compile out drm_device's huge_mnt field in builds with
  CONFIG_TRANSPARENT_HUGEPAGE=n
- add drm_gem_has_huge_mnt() helper

v6:
- move huge_mnt doc into ifdef'd section
- either inline or export drm_gem_huge_mnt_create()

v7:
- include <drm/drm_device.h> in drm_gem.h

v9:
- replace drm_gem_has_huge_mnt() by drm_gem_get_huge_mnt()

v11:
- doc fixes
- add Boris and Maíra R-bs

Signed-off-by: default avatarLoïc Molinari <loic.molinari@collabora.com>
Reviewed-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: default avatarMaíra Canal <mcanal@igalia.com>
Link: https://patch.msgid.link/20251205182231.194072-5-loic.molinari@collabora.com


Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
parent 99bda20d

drivers/gpu/drm/drm_gem.c

+57 −0
Original line number Diff line number Diff line
@@ -29,6 +29,9 @@ 
#include <linux/export.h>

#include <linux/file.h>

#include <linux/fs.h>

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

#include <linux/fs_context.h>

#endif

#include <linux/iosys-map.h>

#include <linux/mem_encrypt.h>

#include <linux/mm.h>
@@ -82,6 +85,60 @@ 
 * up at a later date, and as our interface with shmfs for memory allocation.

 */



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

static void drm_gem_huge_mnt_free(struct drm_device *dev, void *data)

{

	kern_unmount(dev->huge_mnt);

}



/**

 * drm_gem_huge_mnt_create - Create, mount and use a huge tmpfs mountpoint

 * @dev: DRM device that will use the huge tmpfs mountpoint

 * @value: huge tmpfs mount option value

 *

 * This function creates and mounts a dedicated huge tmpfs mountpoint for the

 * lifetime of the DRM device @dev which is used at GEM object initialization

 * with drm_gem_object_init().

 *

 * The most common option for @value is "within_size" which only allocates huge

 * pages if the page will be fully within the GEM object size. "always",

 * "advise" and "never" are supported too but the latter would just create a

 * mountpoint similar to the default one (`shm_mnt`). See shmemfs and

 * Transparent Hugepage for more information.

 *

 * Returns:

 * 0 on success or a negative error code on failure.

 */

int drm_gem_huge_mnt_create(struct drm_device *dev, const char *value)

{

	struct file_system_type *type;

	struct fs_context *fc;

	int ret;



	if (unlikely(drm_gem_get_huge_mnt(dev)))

		return 0;



	type = get_fs_type("tmpfs");

	if (unlikely(!type))

		return -EOPNOTSUPP;

	fc = fs_context_for_mount(type, SB_KERNMOUNT);

	if (IS_ERR(fc))

		return PTR_ERR(fc);

	ret = vfs_parse_fs_string(fc, "source", "tmpfs");

	if (unlikely(ret))

		return -ENOPARAM;

	ret = vfs_parse_fs_string(fc, "huge", value);

	if (unlikely(ret))

		return -ENOPARAM;



	dev->huge_mnt = fc_mount_longterm(fc);

	put_fs_context(fc);



	return drmm_add_action_or_reset(dev, drm_gem_huge_mnt_free, NULL);

}

EXPORT_SYMBOL_GPL(drm_gem_huge_mnt_create);

#endif



static void

drm_gem_init_release(struct drm_device *dev, void *ptr)

{

include/drm/drm_device.h

+15 −0
Original line number Diff line number Diff line
@@ -3,6 +3,9 @@ 


#include <linux/list.h>

#include <linux/kref.h>

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

#include <linux/mount.h>

#endif

#include <linux/mutex.h>

#include <linux/idr.h>

#include <linux/sched.h>
@@ -168,6 +171,18 @@ struct drm_device { 
	 */

	struct drm_master *master;



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	/**

	 * @huge_mnt:

	 *

	 * Huge tmpfs mountpoint used at GEM object initialization

	 * drm_gem_object_init(). Drivers can call drm_gem_huge_mnt_create() to

	 * create, mount and use it. The default tmpfs mountpoint (`shm_mnt`) is

	 * used if NULL.

	 */

	struct vfsmount *huge_mnt;

#endif



	/**

	 * @driver_features: per-device driver features

	 *

include/drm/drm_gem.h

+33 −0
Original line number Diff line number Diff line
@@ -40,6 +40,9 @@ 
#include <linux/list.h>

#include <linux/mutex.h>



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

#include <drm/drm_device.h>

#endif

#include <drm/drm_vma_manager.h>



struct iosys_map;
@@ -492,6 +495,36 @@ struct drm_gem_object { 
		DRM_GEM_FOPS,\

	}



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

int drm_gem_huge_mnt_create(struct drm_device *dev, const char *value);

#else

static inline int drm_gem_huge_mnt_create(struct drm_device *dev,

					  const char *value)

{

	return 0;

}

#endif



/**

 * drm_gem_get_huge_mnt - Get the huge tmpfs mountpoint used by a DRM device

 * @dev: DRM device



 * This function gets the huge tmpfs mountpoint used by DRM device @dev. A huge

 * tmpfs mountpoint is used instead of `shm_mnt` after a successful call to

 * drm_gem_huge_mnt_create() when CONFIG_TRANSPARENT_HUGEPAGE is enabled.



 * Returns:

 * The huge tmpfs mountpoint in use, NULL otherwise.

 */

static inline struct vfsmount *drm_gem_get_huge_mnt(struct drm_device *dev)

{

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	return dev->huge_mnt;

#else

	return NULL;

#endif

}



void drm_gem_object_release(struct drm_gem_object *obj);

void drm_gem_object_free(struct kref *kref);

int drm_gem_object_init(struct drm_device *dev,