Commit 1f430b8d authored by Thomas Hellström's avatar Thomas Hellström
Browse files

drm/xe/svm: Document how xe keeps drm_pagemap references 



As an aid to understanding the lifetime of the drm_pagemaps used
by the xe driver, document how the xe driver keeps the
drm_pagemap references.

v3:
- Fix formatting (Matt Brost)

Suggested-by: default avatarMatthew Brost <matthew.brost@intel.com>
Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarMatthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251219113320.183860-19-thomas.hellstrom@linux.intel.com
parent 54dc5842

drivers/gpu/drm/xe/xe_svm.c

+21 −0
Original line number Diff line number Diff line
@@ -28,6 +28,27 @@ 
#define XE_PEER_PAGEMAP ((void *)0ul)

#define XE_PEER_VM ((void *)1ul)



/**

 * DOC: drm_pagemap reference-counting in xe:

 *

 * In addition to the drm_pagemap internal reference counting by its zone

 * device data, the xe driver holds the following long-time references:

 *

 * - struct xe_pagemap:

 *	The xe_pagemap struct derives from struct drm_pagemap and uses its

 *	reference count.

 * - SVM-enabled VMs:

 *	SVM-enabled VMs look up and keeps a reference to all xe_pagemaps on

 *	the same device.

 * - VMAs:

 *	vmas keep a reference on the drm_pagemap indicated by a gpu_madvise()

 *	call.

 *

 * In addition, all drm_pagemap or xe_pagemap pointers where lifetime cannot

 * be guaranteed by a vma reference under the vm lock should keep a reference.

 * That includes the range->pages.dpagemap pointer.

 */



static int xe_svm_get_pagemaps(struct xe_vm *vm);



void *xe_svm_private_page_owner(struct xe_vm *vm, bool force_smem)