drm/tests: Add a test case for drm buddy clear allocation

Add a new test case for the drm buddy clear and dirty
allocation.

v2:(Matthew)
  - make size as u32
  - rename PAGE_SIZE with SZ_4K
  - dont fragment the address space for all the order allocation
    iterations. we can do it once and just increment and allocate
    the size.
  - create new mm with non power-of-two size to ensure the multi-root
    force_merge during fini.

v3:
  - add randomness in size calculation(Matthew)
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Suggested-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240419063538.11957-3-Arunpravin.PaneerSelvam@amd.comSigned-off-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/tests/drm_buddy_test.c

@@ -224,6 +224,148 @@ static void drm_test_buddy_alloc_range_bias(struct kunit *test)
 	drm_buddy_fini(&mm);
 }
 
+static void drm_test_buddy_alloc_clear(struct kunit *test)
+{
+	unsigned long n_pages, total, i = 0;
+	DRM_RND_STATE(prng, random_seed);
+	const unsigned long ps = SZ_4K;
+	struct drm_buddy_block *block;
+	const int max_order = 12;
+	LIST_HEAD(allocated);
+	struct drm_buddy mm;
+	unsigned int order;
+	u32 mm_size, size;
+	LIST_HEAD(dirty);
+	LIST_HEAD(clean);
+
+	mm_size = SZ_4K << max_order;
+	KUNIT_EXPECT_FALSE(test, drm_buddy_init(&mm, mm_size, ps));
+
+	KUNIT_EXPECT_EQ(test, mm.max_order, max_order);
+
+	/*
+	 * Idea is to allocate and free some random portion of the address space,
+	 * returning those pages as non-dirty and randomly alternate between
+	 * requesting dirty and non-dirty pages (not going over the limit
+	 * we freed as non-dirty), putting that into two separate lists.
+	 * Loop over both lists at the end checking that the dirty list
+	 * is indeed all dirty pages and vice versa. Free it all again,
+	 * keeping the dirty/clear status.
+	 */
+	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
+							    5 * ps, ps, &allocated,
+							    DRM_BUDDY_TOPDOWN_ALLOCATION),
+				"buddy_alloc hit an error size=%lu\n", 5 * ps);
+	drm_buddy_free_list(&mm, &allocated, DRM_BUDDY_CLEARED);
+
+	n_pages = 10;
+	do {
+		unsigned long flags;
+		struct list_head *list;
+		int slot = i % 2;
+
+		if (slot == 0) {
+			list = &dirty;
+			flags = 0;
+		} else {
+			list = &clean;
+			flags = DRM_BUDDY_CLEAR_ALLOCATION;
+		}
+
+		KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
+								    ps, ps, list,
+								    flags),
+					"buddy_alloc hit an error size=%lu\n", ps);
+	} while (++i < n_pages);
+
+	list_for_each_entry(block, &clean, link)
+		KUNIT_EXPECT_EQ(test, drm_buddy_block_is_clear(block), true);
+
+	list_for_each_entry(block, &dirty, link)
+		KUNIT_EXPECT_EQ(test, drm_buddy_block_is_clear(block), false);
+
+	drm_buddy_free_list(&mm, &clean, DRM_BUDDY_CLEARED);
+
+	/*
+	 * Trying to go over the clear limit for some allocation.
+	 * The allocation should never fail with reasonable page-size.
+	 */
+	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
+							    10 * ps, ps, &clean,
+							    DRM_BUDDY_CLEAR_ALLOCATION),
+				"buddy_alloc hit an error size=%lu\n", 10 * ps);
+
+	drm_buddy_free_list(&mm, &clean, DRM_BUDDY_CLEARED);
+	drm_buddy_free_list(&mm, &dirty, 0);
+	drm_buddy_fini(&mm);
+
+	KUNIT_EXPECT_FALSE(test, drm_buddy_init(&mm, mm_size, ps));
+
+	/*
+	 * Create a new mm. Intentionally fragment the address space by creating
+	 * two alternating lists. Free both lists, one as dirty the other as clean.
+	 * Try to allocate double the previous size with matching min_page_size. The
+	 * allocation should never fail as it calls the force_merge. Also check that
+	 * the page is always dirty after force_merge. Free the page as dirty, then
+	 * repeat the whole thing, increment the order until we hit the max_order.
+	 */
+
+	i = 0;
+	n_pages = mm_size / ps;
+	do {
+		struct list_head *list;
+		int slot = i % 2;
+
+		if (slot == 0)
+			list = &dirty;
+		else
+			list = &clean;
+
+		KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
+								    ps, ps, list, 0),
+					"buddy_alloc hit an error size=%lu\n", ps);
+	} while (++i < n_pages);
+
+	drm_buddy_free_list(&mm, &clean, DRM_BUDDY_CLEARED);
+	drm_buddy_free_list(&mm, &dirty, 0);
+
+	order = 1;
+	do {
+		size = SZ_4K << order;
+
+		KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
+								    size, size, &allocated,
+								    DRM_BUDDY_CLEAR_ALLOCATION),
+					"buddy_alloc hit an error size=%u\n", size);
+		total = 0;
+		list_for_each_entry(block, &allocated, link) {
+			if (size != mm_size)
+				KUNIT_EXPECT_EQ(test, drm_buddy_block_is_clear(block), false);
+			total += drm_buddy_block_size(&mm, block);
+		}
+		KUNIT_EXPECT_EQ(test, total, size);
+
+		drm_buddy_free_list(&mm, &allocated, 0);
+	} while (++order <= max_order);
+
+	drm_buddy_fini(&mm);
+
+	/*
+	 * Create a new mm with a non power-of-two size. Allocate a random size, free as
+	 * cleared and then call fini. This will ensure the multi-root force merge during
+	 * fini.
+	 */
+	mm_size = 12 * SZ_4K;
+	size = max(round_up(prandom_u32_state(&prng) % mm_size, ps), ps);
+	KUNIT_EXPECT_FALSE(test, drm_buddy_init(&mm, mm_size, ps));
+	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
+							    size, ps, &allocated,
+							    DRM_BUDDY_TOPDOWN_ALLOCATION),
+				"buddy_alloc hit an error size=%u\n", size);
+	drm_buddy_free_list(&mm, &allocated, DRM_BUDDY_CLEARED);
+	drm_buddy_fini(&mm);
+}
+
 static void drm_test_buddy_alloc_contiguous(struct kunit *test)
 {
 	const unsigned long ps = SZ_4K, mm_size = 16 * 3 * SZ_4K;
@@ -584,6 +726,7 @@ static struct kunit_case drm_buddy_tests[] = {
 	KUNIT_CASE(drm_test_buddy_alloc_pessimistic),
 	KUNIT_CASE(drm_test_buddy_alloc_pathological),
 	KUNIT_CASE(drm_test_buddy_alloc_contiguous),
+	KUNIT_CASE(drm_test_buddy_alloc_clear),
 	KUNIT_CASE(drm_test_buddy_alloc_range_bias),
 	{}
 };