drm/xe: Add a xe_bo subtest for shrinking / swapping

Add a subtest that tries to allocate twice the amount of
buffer object memory available, write data to it and then read
all the data back verifying data integrity.
In order to be able to do this on systems that
have no or not enough swap-space available, allocate some memory
as purgeable, and introduce a function to purge such memory from
the TTM swap_notify path.

this test is intended to add test coverage to the current
bo swap path and upcoming shrinking path.

The test has previously been part of the xe bo shrinker series.

v2:
- Skip test if the execution time is expected to be too long.
- Minor code cleanups.

v3:
- Print random seed. (Matthew Auld)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240909085654.5064-1-thomas.hellstrom@linux.intel.com

1 files changed, 31 insertions, 1 deletions

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 3a9653e33481..0dc8ebcf8389 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -283,6 +283,8 @@ struct xe_ttm_tt {
 	struct device *dev;
 	struct sg_table sgt;
 	struct sg_table *sg;
+	/** @purgeable: Whether the content of the pages of @ttm is purgeable. */
+	bool purgeable;
 };
 
 static int xe_tt_map_sg(struct ttm_tt *tt)
@@ -761,7 +763,7 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict,
 	if (xe_rpm_reclaim_safe(xe)) {
 		/*
 		 * We might be called through swapout in the validation path of
-		 * another TTM device, so unconditionally acquire rpm here.
+		 * another TTM device, so acquire rpm here.
 		 */
 		xe_pm_runtime_get(xe);
 	} else {
@@ -1082,6 +1084,33 @@ static void xe_ttm_bo_delete_mem_notify(struct ttm_buffer_object *ttm_bo)
 	}
 }
 
+static void xe_ttm_bo_purge(struct ttm_buffer_object *ttm_bo, struct ttm_operation_ctx *ctx)
+{
+	struct xe_device *xe = ttm_to_xe_device(ttm_bo->bdev);
+
+	if (ttm_bo->ttm) {
+		struct ttm_placement place = {};
+		int ret = ttm_bo_validate(ttm_bo, &place, ctx);
+
+		drm_WARN_ON(&xe->drm, ret);
+	}
+}
+
+static void xe_ttm_bo_swap_notify(struct ttm_buffer_object *ttm_bo)
+{
+	struct ttm_operation_ctx ctx = {
+		.interruptible = false
+	};
+
+	if (ttm_bo->ttm) {
+		struct xe_ttm_tt *xe_tt =
+			container_of(ttm_bo->ttm, struct xe_ttm_tt, ttm);
+
+		if (xe_tt->purgeable)
+			xe_ttm_bo_purge(ttm_bo, &ctx);
+	}
+}
+
 const struct ttm_device_funcs xe_ttm_funcs = {
 	.ttm_tt_create = xe_ttm_tt_create,
 	.ttm_tt_populate = xe_ttm_tt_populate,
@@ -1094,6 +1123,7 @@ const struct ttm_device_funcs xe_ttm_funcs = {
 	.release_notify = xe_ttm_bo_release_notify,
 	.eviction_valuable = ttm_bo_eviction_valuable,
 	.delete_mem_notify = xe_ttm_bo_delete_mem_notify,
+	.swap_notify = xe_ttm_bo_swap_notify,
 };
 
 static void xe_ttm_bo_destroy(struct ttm_buffer_object *ttm_bo)