[RFC PATCH 1/9] drm/xe/uapi: Add UAPI support for purgeable buffer objects

[Arvind Yadav <arvind.yadav@intel.com>]

From: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>

Extend the DRM_XE_MADVISE ioctl to support purgeable buffer object
management by adding DRM_XE_VMA_ATTR_PURGEABLE_STATE attribute type.

This allows userspace applications to provide memory usage hints to
the kernel for better memory management under pressure:

- WILLNEED: BO will be needed again, re-validate if purged.
- DONTNEED: Buffer not currently needed, may be purged if needed.

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
---
 include/uapi/drm/xe_drm.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
index 47853659a705..e5345101a92a 100644
--- a/include/uapi/drm/xe_drm.h
+++ b/include/uapi/drm/xe_drm.h
@@ -2051,6 +2051,7 @@ struct drm_xe_madvise {
 #define DRM_XE_MEM_RANGE_ATTR_PREFERRED_LOC	0
 #define DRM_XE_MEM_RANGE_ATTR_ATOMIC		1
 #define DRM_XE_MEM_RANGE_ATTR_PAT		2
+#define DRM_XE_VMA_ATTR_PURGEABLE_STATE		3
 	/** @type: type of attribute */
 	__u32 type;
 
@@ -2129,6 +2130,30 @@ struct drm_xe_madvise {
 			/** @pat_index.reserved: Reserved */
 			__u64 reserved;
 		} pat_index;
+
+		/**
+		 * @purge_state_val: Purgeable state configuration
+		 *
+		 * Used when @type == DRM_XE_VMA_ATTR_PURGEABLE_STATE.
+		 *
+		 * Configures the purgeable state of buffer objects in the specified
+		 * virtual address range. This allows applications to hint to the kernel
+		 * about bo's usage patterns for better memory management.
+		 *
+		 * Supported values for @purge_state_val.val:
+		 *  - DRM_XE_VMA_PURGEABLE_STATE_WILLNEED: BO is needed,
+		 *    should not be purged by the kernel.
+		 *  - DRM_XE_VMA_PURGEABLE_STATE_DONTNEED: BO is not currently needed,
+		 *    kernel may purge it to free memory if under pressure.
+		 */
+		struct {
+#define DRM_XE_VMA_PURGEABLE_STATE_WILLNEED	0
+#define DRM_XE_VMA_PURGEABLE_STATE_DONTNEED	1
+			/** @purge_state_val.val: value for DRM_XE_VMA_ATTR_PURGEABLE_STATE */
+			__u32 val;
+			/** @purge_state_val.reserved: Reserved */
+			__u32 reserved;
+		} purge_state_val;
 	};
 
 	/** @reserved: Reserved */
-- 
2.43.0