drm/i915/selftests: Tighten the timeout testing for partial mmaps

Currently, if there is time remaining before the start of the loop, we
do one full iteration over many possible different chunks within the
object. A full loop may take 50+s (depending on speed of indirect GTT
mmapings) and we try separately with LINEAR, X and Y -- at which point
igt times out. If we check more frequently, we will interrupt the loop
upon our timeout -- it is hard to argue for as this significantly reduces
the test coverage as we dramatically reduce the runtime. In practical
terms, the coverage we should prioritise is in using different fence
setups, forcing verification of the tile row computations over the
current preference of checking extracting chunks. Though the exhaustive
search is great given an infinite timeout, to improve our current
coverage, we also add a randomised smoketest of partial mmaps. So let's
do both, add a randomised smoketest of partial tiling chunks and the
exhaustive (though time limited) search for failures.

Even in adding another subtest, we should shave 100s off BAT! (With,
hopefully, no loss in coverage, at least over multiple runs.)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190910121009.13431-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c

@@ -10,6 +10,7 @@
 #include "gt/intel_gt_pm.h"
 #include "huge_gem_object.h"
 #include "i915_selftest.h"
+#include "selftests/i915_random.h"
 #include "selftests/igt_flush_test.h"
 
 struct tile {
@@ -76,18 +77,103 @@ static u64 tiled_offset(const struct tile *tile, u64 v)
 
 static int check_partial_mapping(struct drm_i915_gem_object *obj,
 				 const struct tile *tile,
-				 unsigned long end_time)
+				 struct rnd_state *prng)
 {
-	const unsigned int nreal = obj->scratch / PAGE_SIZE;
 	const unsigned long npages = obj->base.size / PAGE_SIZE;
+	struct i915_ggtt_view view;
 	struct i915_vma *vma;
 	unsigned long page;
+	u32 __iomem *io;
+	struct page *p;
+	unsigned int n;
+	u64 offset;
+	u32 *cpu;
 	int err;
 
-	if (igt_timeout(end_time,
-			"%s: timed out before tiling=%d stride=%d\n",
-			__func__, tile->tiling, tile->stride))
-		return -EINTR;
+	err = i915_gem_object_set_tiling(obj, tile->tiling, tile->stride);
+	if (err) {
+		pr_err("Failed to set tiling mode=%u, stride=%u, err=%d\n",
+		       tile->tiling, tile->stride, err);
+		return err;
+	}
+
+	GEM_BUG_ON(i915_gem_object_get_tiling(obj) != tile->tiling);
+	GEM_BUG_ON(i915_gem_object_get_stride(obj) != tile->stride);
+
+	i915_gem_object_lock(obj);
+	err = i915_gem_object_set_to_gtt_domain(obj, true);
+	i915_gem_object_unlock(obj);
+	if (err) {
+		pr_err("Failed to flush to GTT write domain; err=%d\n", err);
+		return err;
+	}
+
+	page = i915_prandom_u32_max_state(npages, prng);
+	view = compute_partial_view(obj, page, MIN_CHUNK_PAGES);
+
+	vma = i915_gem_object_ggtt_pin(obj, &view, 0, 0, PIN_MAPPABLE);
+	if (IS_ERR(vma)) {
+		pr_err("Failed to pin partial view: offset=%lu; err=%d\n",
+		       page, (int)PTR_ERR(vma));
+		return PTR_ERR(vma);
+	}
+
+	n = page - view.partial.offset;
+	GEM_BUG_ON(n >= view.partial.size);
+
+	io = i915_vma_pin_iomap(vma);
+	i915_vma_unpin(vma);
+	if (IS_ERR(io)) {
+		pr_err("Failed to iomap partial view: offset=%lu; err=%d\n",
+		       page, (int)PTR_ERR(io));
+		err = PTR_ERR(io);
+		goto out;
+	}
+
+	iowrite32(page, io + n * PAGE_SIZE / sizeof(*io));
+	i915_vma_unpin_iomap(vma);
+
+	offset = tiled_offset(tile, page << PAGE_SHIFT);
+	if (offset >= obj->base.size)
+		goto out;
+
+	intel_gt_flush_ggtt_writes(&to_i915(obj->base.dev)->gt);
+
+	p = i915_gem_object_get_page(obj, offset >> PAGE_SHIFT);
+	cpu = kmap(p) + offset_in_page(offset);
+	drm_clflush_virt_range(cpu, sizeof(*cpu));
+	if (*cpu != (u32)page) {
+		pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%llu + %u [0x%llx]) of 0x%x, found 0x%x\n",
+		       page, n,
+		       view.partial.offset,
+		       view.partial.size,
+		       vma->size >> PAGE_SHIFT,
+		       tile->tiling ? tile_row_pages(obj) : 0,
+		       vma->fence ? vma->fence->id : -1, tile->tiling, tile->stride,
+		       offset >> PAGE_SHIFT,
+		       (unsigned int)offset_in_page(offset),
+		       offset,
+		       (u32)page, *cpu);
+		err = -EINVAL;
+	}
+	*cpu = 0;
+	drm_clflush_virt_range(cpu, sizeof(*cpu));
+	kunmap(p);
+
+out:
+	i915_vma_destroy(vma);
+	return err;
+}
+
+static int check_partial_mappings(struct drm_i915_gem_object *obj,
+				  const struct tile *tile,
+				  unsigned long end_time)
+{
+	const unsigned int nreal = obj->scratch / PAGE_SIZE;
+	const unsigned long npages = obj->base.size / PAGE_SIZE;
+	struct i915_vma *vma;
+	unsigned long page;
+	int err;
 
 	err = i915_gem_object_set_tiling(obj, tile->tiling, tile->stride);
 	if (err) {
@@ -170,11 +256,42 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
 			return err;
 
 		i915_vma_destroy(vma);
+
+		if (igt_timeout(end_time,
+				"%s: timed out after tiling=%d stride=%d\n",
+				__func__, tile->tiling, tile->stride))
+			return -EINTR;
 	}
 
 	return 0;
 }
 
+static unsigned int
+setup_tile_size(struct tile *tile, struct drm_i915_private *i915)
+{
+	if (INTEL_GEN(i915) <= 2) {
+		tile->height = 16;
+		tile->width = 128;
+		tile->size = 11;
+	} else if (tile->tiling == I915_TILING_Y &&
+		   HAS_128_BYTE_Y_TILING(i915)) {
+		tile->height = 32;
+		tile->width = 128;
+		tile->size = 12;
+	} else {
+		tile->height = 8;
+		tile->width = 512;
+		tile->size = 12;
+	}
+
+	if (INTEL_GEN(i915) < 4)
+		return 8192 / tile->width;
+	else if (INTEL_GEN(i915) < 7)
+		return 128 * I965_FENCE_MAX_PITCH_VAL / tile->width;
+	else
+		return 128 * GEN7_FENCE_MAX_PITCH_VAL / tile->width;
+}
+
 static int igt_partial_tiling(void *arg)
 {
 	const unsigned int nreal = 1 << 12; /* largest tile row x2 */
@@ -219,7 +336,7 @@ static int igt_partial_tiling(void *arg)
 		tile.swizzle = I915_BIT_6_SWIZZLE_NONE;
 		tile.tiling = I915_TILING_NONE;
 
-		err = check_partial_mapping(obj, &tile, end);
+		err = check_partial_mappings(obj, &tile, end);
 		if (err && err != -EINTR)
 			goto out_unlock;
 	}
@@ -253,31 +370,11 @@ static int igt_partial_tiling(void *arg)
 		    tile.swizzle == I915_BIT_6_SWIZZLE_9_10_17)
 			continue;
 
-		if (INTEL_GEN(i915) <= 2) {
-			tile.height = 16;
-			tile.width = 128;
-			tile.size = 11;
-		} else if (tile.tiling == I915_TILING_Y &&
-			   HAS_128_BYTE_Y_TILING(i915)) {
-			tile.height = 32;
-			tile.width = 128;
-			tile.size = 12;
-		} else {
-			tile.height = 8;
-			tile.width = 512;
-			tile.size = 12;
-		}
-
-		if (INTEL_GEN(i915) < 4)
-			max_pitch = 8192 / tile.width;
-		else if (INTEL_GEN(i915) < 7)
-			max_pitch = 128 * I965_FENCE_MAX_PITCH_VAL / tile.width;
-		else
-			max_pitch = 128 * GEN7_FENCE_MAX_PITCH_VAL / tile.width;
+		max_pitch = setup_tile_size(&tile, i915);
 
 		for (pitch = max_pitch; pitch; pitch >>= 1) {
 			tile.stride = tile.width * pitch;
-			err = check_partial_mapping(obj, &tile, end);
+			err = check_partial_mappings(obj, &tile, end);
 			if (err == -EINTR)
 				goto next_tiling;
 			if (err)
@@ -285,7 +382,7 @@ static int igt_partial_tiling(void *arg)
 
 			if (pitch > 2 && INTEL_GEN(i915) >= 4) {
 				tile.stride = tile.width * (pitch - 1);
-				err = check_partial_mapping(obj, &tile, end);
+				err = check_partial_mappings(obj, &tile, end);
 				if (err == -EINTR)
 					goto next_tiling;
 				if (err)
@@ -294,7 +391,7 @@ static int igt_partial_tiling(void *arg)
 
 			if (pitch < max_pitch && INTEL_GEN(i915) >= 4) {
 				tile.stride = tile.width * (pitch + 1);
-				err = check_partial_mapping(obj, &tile, end);
+				err = check_partial_mappings(obj, &tile, end);
 				if (err == -EINTR)
 					goto next_tiling;
 				if (err)
@@ -305,7 +402,7 @@ static int igt_partial_tiling(void *arg)
 		if (INTEL_GEN(i915) >= 4) {
 			for_each_prime_number(pitch, max_pitch) {
 				tile.stride = tile.width * pitch;
-				err = check_partial_mapping(obj, &tile, end);
+				err = check_partial_mappings(obj, &tile, end);
 				if (err == -EINTR)
 					goto next_tiling;
 				if (err)
@@ -325,6 +422,99 @@ next_tiling: ;
 	return err;
 }
 
+static int igt_smoke_tiling(void *arg)
+{
+	const unsigned int nreal = 1 << 12; /* largest tile row x2 */
+	struct drm_i915_private *i915 = arg;
+	struct drm_i915_gem_object *obj;
+	intel_wakeref_t wakeref;
+	I915_RND_STATE(prng);
+	unsigned long count;
+	IGT_TIMEOUT(end);
+	int err;
+
+	/*
+	 * igt_partial_tiling() does an exhastive check of partial tiling
+	 * chunking, but will undoubtably run out of time. Here, we do a
+	 * randomised search and hope over many runs of 1s with different
+	 * seeds we will do a thorough check.
+	 *
+	 * Remember to look at the st_seed if we see a flip-flop in BAT!
+	 */
+
+	if (i915->quirks & QUIRK_PIN_SWIZZLED_PAGES)
+		return 0;
+
+	obj = huge_gem_object(i915,
+			      nreal << PAGE_SHIFT,
+			      (1 + next_prime_number(i915->ggtt.vm.total >> PAGE_SHIFT)) << PAGE_SHIFT);
+	if (IS_ERR(obj))
+		return PTR_ERR(obj);
+
+	err = i915_gem_object_pin_pages(obj);
+	if (err) {
+		pr_err("Failed to allocate %u pages (%lu total), err=%d\n",
+		       nreal, obj->base.size / PAGE_SIZE, err);
+		goto out;
+	}
+
+	mutex_lock(&i915->drm.struct_mutex);
+	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
+
+	count = 0;
+	do {
+		struct tile tile;
+
+		tile.tiling =
+			i915_prandom_u32_max_state(I915_TILING_Y + 1, &prng);
+		switch (tile.tiling) {
+		case I915_TILING_NONE:
+			tile.height = 1;
+			tile.width = 1;
+			tile.size = 0;
+			tile.stride = 0;
+			tile.swizzle = I915_BIT_6_SWIZZLE_NONE;
+			break;
+
+		case I915_TILING_X:
+			tile.swizzle = i915->mm.bit_6_swizzle_x;
+			break;
+		case I915_TILING_Y:
+			tile.swizzle = i915->mm.bit_6_swizzle_y;
+			break;
+		}
+
+		if (tile.swizzle == I915_BIT_6_SWIZZLE_9_17 ||
+		    tile.swizzle == I915_BIT_6_SWIZZLE_9_10_17)
+			continue;
+
+		if (tile.tiling != I915_TILING_NONE) {
+			unsigned int max_pitch = setup_tile_size(&tile, i915);
+
+			tile.stride =
+				i915_prandom_u32_max_state(max_pitch, &prng);
+			tile.stride = (1 + tile.stride) * tile.width;
+			if (INTEL_GEN(i915) < 4)
+				tile.stride = rounddown_pow_of_two(tile.stride);
+		}
+
+		err = check_partial_mapping(obj, &tile, &prng);
+		if (err)
+			break;
+
+		count++;
+	} while (!__igt_timeout(end, NULL));
+
+	pr_info("%s: Completed %lu trials\n", __func__, count);
+
+	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
+	mutex_unlock(&i915->drm.struct_mutex);
+	i915_gem_object_unpin_pages(obj);
+out:
+	i915_gem_object_put(obj);
+	return err;
+}
+
 static int make_obj_busy(struct drm_i915_gem_object *obj)
 {
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
@@ -515,6 +705,7 @@ int i915_gem_mman_live_selftests(struct drm_i915_private *i915)
 {
 	static const struct i915_subtest tests[] = {
 		SUBTEST(igt_partial_tiling),
+		SUBTEST(igt_smoke_tiling),
 		SUBTEST(igt_mmap_offset_exhaustion),
 	};