[PATCH v4 1/8] drm/xe: add page size allocation control state to xe_device

[Nareshkumar Gollakoti <naresh.kumar.g@intel.com>]

Introduce xe_page_size_alloc_ctrl_mode and add page_size_alloc_ctrl
state to struct xe_device along with mutex lock.

The new control supports forcing user BO allocations to 2M pages,
forcing them to 1G pages, or using a mixed round-robin mode across
4K, 64K, 2M, and 1G page sizes. Track the current mixed-mode index
in xe_device so allocation policy can be applied consistently.

v2
- make cur_index to atomic as update need in later patch to
  avoid race/concurency (sashiko)
v3
- reworded comments
- protect mode/index updates with a mutex for proper concurrency handling

v4(sashiko)
- move xe_debug_page_size_alloc_ctrl_init() before drm_dev_register(),
  so mutex and control states are initialized
  before any userspace visibility

Signed-off-by: Nareshkumar Gollakoti <naresh.kumar.g@intel.com>
---
 drivers/gpu/drm/xe/xe_device.c       |  9 +++++++++
 drivers/gpu/drm/xe/xe_device_types.h | 25 +++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index c9fa4bfed2b9..6143e3603023 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -923,6 +923,13 @@ static void xe_device_wedged_fini(struct drm_device *drm, void *arg)
 		xe_pm_runtime_put(xe);
 }
 
+static void xe_debug_page_size_alloc_ctrl_init(struct xe_device *xe)
+{
+	mutex_init(&xe->page_size_alloc_ctrl.lock);
+	xe->page_size_alloc_ctrl.mode = XE_PAGE_SIZE_ALLOC_CTRL_MODE_NONE;
+	xe->page_size_alloc_ctrl.cur_index = 0;
+}
+
 int xe_device_probe(struct xe_device *xe)
 {
 	struct xe_tile *tile;
@@ -1075,6 +1082,8 @@ int xe_device_probe(struct xe_device *xe)
 	if (err)
 		return err;
 
+	xe_debug_page_size_alloc_ctrl_init(xe);
+
 	err = drm_dev_register(&xe->drm, 0);
 	if (err)
 		return err;
diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 022e08205897..8cd70756413b 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -61,6 +61,21 @@ enum xe_wedged_mode {
 	XE_WEDGED_MODE_UPON_ANY_HANG_NO_RESET = 2,
 };
 
+/**
+ * enum xe_page_size_alloc_ctrl_mode - User BO page-size allocation control modes
+ * @XE_PAGE_SIZE_ALLOC_CTRL_MODE_NONE: Use the normal allocation policy
+ * @XE_PAGE_SIZE_ALLOC_CTRL_MODE_ONLY_2M: Force user BO allocations to 2M pages
+ * @XE_PAGE_SIZE_ALLOC_CTRL_MODE_ONLY_1G: Force user BO allocations to 1G pages
+ * @XE_PAGE_SIZE_ALLOC_CTRL_MODE_MIXED: Select page sizes in round-robin order
+ *     (4K, 64K, 2M, 1G)
+ */
+enum xe_page_size_alloc_ctrl_mode {
+	XE_PAGE_SIZE_ALLOC_CTRL_MODE_NONE = 0,
+	XE_PAGE_SIZE_ALLOC_CTRL_MODE_ONLY_2M,
+	XE_PAGE_SIZE_ALLOC_CTRL_MODE_ONLY_1G,
+	XE_PAGE_SIZE_ALLOC_CTRL_MODE_MIXED
+};
+
 #define XE_BO_INVALID_OFFSET	LONG_MAX
 
 #define GRAPHICS_VER(xe) ((xe)->info.graphics_verx100 / 100)
@@ -474,6 +489,16 @@ struct xe_device {
 	/** @late_bind: xe mei late bind interface */
 	struct xe_late_bind late_bind;
 
+	/** @page_size_alloc_ctrl: User BO page-size allocation debug control state */
+	struct {
+		/** @mode: xe page size allocation control mode */
+		enum xe_page_size_alloc_ctrl_mode mode;
+		/** @cur_index: Round-robin index used by mixed mode */
+		u32 cur_index;
+		/** @lock: Protects @mode and @cur_index */
+		struct mutex lock;
+	} page_size_alloc_ctrl;
+
 	/** @oa: oa observation subsystem */
 	struct xe_oa oa;
 
-- 
2.43.0