drivers/gpu/drm/i915/selftests/i915_gem_context.c - pub/scm/linux/kernel/git/kbingham/rcar - Git at Google

 /*
  * Copyright © 2017 Intel Corporation
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice (including the next
  * paragraph) shall be included in all copies or substantial portions of the
  * Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  * IN THE SOFTWARE.
  *
  */

 #include "../i915_selftest.h"

 #include "mock_drm.h"
 #include "huge_gem_object.h"

 #define DW_PER_PAGE (PAGE_SIZE / sizeof(u32))

 static struct i915_vma *
 gpu_fill_dw(struct i915_vma *vma, u64 offset, unsigned long count, u32 value)
 {
 	struct drm_i915_gem_object *obj;
 	const int gen = INTEL_GEN(vma->vm->i915);
 	unsigned long n, size;
 	u32 *cmd;
 	int err;

 	GEM_BUG_ON(!igt_can_mi_store_dword_imm(vma->vm->i915));

 	size = (4 * count + 1) * sizeof(u32);
 	size = round_up(size, PAGE_SIZE);
 	obj = i915_gem_object_create_internal(vma->vm->i915, size);
 	if (IS_ERR(obj))
 		return ERR_CAST(obj);

 	cmd = i915_gem_object_pin_map(obj, I915_MAP_WB);
 	if (IS_ERR(cmd)) {
 		err = PTR_ERR(cmd);
 		goto err;
 	}

 	GEM_BUG_ON(offset + (count - 1) * PAGE_SIZE > vma->node.size);
 	offset += vma->node.start;

 	for (n = 0; n < count; n++) {
 		if (gen >= 8) {
 			*cmd++ = MI_STORE_DWORD_IMM_GEN4;
 			*cmd++ = lower_32_bits(offset);
 			*cmd++ = upper_32_bits(offset);
 			*cmd++ = value;
 		} else if (gen >= 4) {
 			*cmd++ = MI_STORE_DWORD_IMM_GEN4 |
 				(gen < 6 ? 1 << 22 : 0);
 			*cmd++ = 0;
 			*cmd++ = offset;
 			*cmd++ = value;
 		} else {
 			*cmd++ = MI_STORE_DWORD_IMM | 1 << 22;
 			*cmd++ = offset;
 			*cmd++ = value;
 		}
 		offset += PAGE_SIZE;
 	}
 	*cmd = MI_BATCH_BUFFER_END;
 	i915_gem_object_unpin_map(obj);

 	err = i915_gem_object_set_to_gtt_domain(obj, false);
 	if (err)
 		goto err;

 	vma = i915_vma_instance(obj, vma->vm, NULL);
 	if (IS_ERR(vma)) {
 		err = PTR_ERR(vma);
 		goto err;
 	}

 	err = i915_vma_pin(vma, 0, 0, PIN_USER);
 	if (err)
 		goto err;

 	return vma;

 err:
 	i915_gem_object_put(obj);
 	return ERR_PTR(err);
 }

 static unsigned long real_page_count(struct drm_i915_gem_object *obj)
 {
 	return huge_gem_object_phys_size(obj) >> PAGE_SHIFT;
 }

 static unsigned long fake_page_count(struct drm_i915_gem_object *obj)
 {
 	return huge_gem_object_dma_size(obj) >> PAGE_SHIFT;
 }

 static int gpu_fill(struct drm_i915_gem_object *obj,
 		    struct i915_gem_context *ctx,
 		    struct intel_engine_cs *engine,
 		    unsigned int dw)
 {
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct i915_address_space *vm =
 		ctx->ppgtt ? &ctx->ppgtt->base : &i915->ggtt.base;
 	struct drm_i915_gem_request *rq;
 	struct i915_vma *vma;
 	struct i915_vma *batch;
 	unsigned int flags;
 	int err;

 	GEM_BUG_ON(obj->base.size > vm->total);

 	vma = i915_vma_instance(obj, vm, NULL);
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);

 	err = i915_gem_object_set_to_gtt_domain(obj, false);
 	if (err)
 		return err;

 	err = i915_vma_pin(vma, 0, 0, PIN_HIGH | PIN_USER);
 	if (err)
 		return err;

 	/* Within the GTT the huge objects maps every page onto
 	 * its 1024 real pages (using phys_pfn = dma_pfn % 1024).
 	 * We set the nth dword within the page using the nth
 	 * mapping via the GTT - this should exercise the GTT mapping
 	 * whilst checking that each context provides a unique view
 	 * into the object.
 	 */
 	batch = gpu_fill_dw(vma,
 			    (dw * real_page_count(obj)) << PAGE_SHIFT |
 			    (dw * sizeof(u32)),
 			    real_page_count(obj),
 			    dw);
 	if (IS_ERR(batch)) {
 		err = PTR_ERR(batch);
 		goto err_vma;
 	}

 	rq = i915_gem_request_alloc(engine, ctx);
 	if (IS_ERR(rq)) {
 		err = PTR_ERR(rq);
 		goto err_batch;
 	}

 	err = engine->emit_flush(rq, EMIT_INVALIDATE);
 	if (err)
 		goto err_request;

 	err = i915_switch_context(rq);
 	if (err)
 		goto err_request;

 	flags = 0;
 	if (INTEL_GEN(vm->i915) <= 5)
 		flags |= I915_DISPATCH_SECURE;

 	err = engine->emit_bb_start(rq,
 				    batch->node.start, batch->node.size,
 				    flags);
 	if (err)
 		goto err_request;

 	i915_vma_move_to_active(batch, rq, 0);
 	i915_gem_object_set_active_reference(batch->obj);
 	i915_vma_unpin(batch);
 	i915_vma_close(batch);

 	i915_vma_move_to_active(vma, rq, 0);
 	i915_vma_unpin(vma);

 	reservation_object_lock(obj->resv, NULL);
 	reservation_object_add_excl_fence(obj->resv, &rq->fence);
 	reservation_object_unlock(obj->resv);

 	__i915_add_request(rq, true);

 	return 0;

 err_request:
 	__i915_add_request(rq, false);
 err_batch:
 	i915_vma_unpin(batch);
 err_vma:
 	i915_vma_unpin(vma);
 	return err;
 }

 static int cpu_fill(struct drm_i915_gem_object *obj, u32 value)
 {
 	const bool has_llc = HAS_LLC(to_i915(obj->base.dev));
 	unsigned int n, m, need_flush;
 	int err;

 	err = i915_gem_obj_prepare_shmem_write(obj, &need_flush);
 	if (err)
 		return err;

 	for (n = 0; n < real_page_count(obj); n++) {
 		u32 *map;

 		map = kmap_atomic(i915_gem_object_get_page(obj, n));
 		for (m = 0; m < DW_PER_PAGE; m++)
 			map[m] = value;
 		if (!has_llc)
 			drm_clflush_virt_range(map, PAGE_SIZE);
 		kunmap_atomic(map);
 	}

 	i915_gem_obj_finish_shmem_access(obj);
 	obj->base.read_domains = I915_GEM_DOMAIN_GTT | I915_GEM_DOMAIN_CPU;
 	obj->base.write_domain = 0;
 	return 0;
 }

 static int cpu_check(struct drm_i915_gem_object *obj, unsigned int max)
 {
 	unsigned int n, m, needs_flush;
 	int err;

 	err = i915_gem_obj_prepare_shmem_read(obj, &needs_flush);
 	if (err)
 		return err;

 	for (n = 0; n < real_page_count(obj); n++) {
 		u32 *map;

 		map = kmap_atomic(i915_gem_object_get_page(obj, n));
 		if (needs_flush & CLFLUSH_BEFORE)
 			drm_clflush_virt_range(map, PAGE_SIZE);

 		for (m = 0; m < max; m++) {
 			if (map[m] != m) {
 				pr_err("Invalid value at page %d, offset %d: found %x expected %x\n",
 				       n, m, map[m], m);
 				err = -EINVAL;
 				goto out_unmap;
 			}
 		}

 		for (; m < DW_PER_PAGE; m++) {
 			if (map[m] != 0xdeadbeef) {
 				pr_err("Invalid value at page %d, offset %d: found %x expected %x\n",
 				       n, m, map[m], 0xdeadbeef);
 				err = -EINVAL;
 				goto out_unmap;
 			}
 		}

 out_unmap:
 		kunmap_atomic(map);
 		if (err)
 			break;
 	}

 	i915_gem_obj_finish_shmem_access(obj);
 	return err;
 }

 static struct drm_i915_gem_object *
 create_test_object(struct i915_gem_context *ctx,
 		   struct drm_file *file,
 		   struct list_head *objects)
 {
 	struct drm_i915_gem_object *obj;
 	struct i915_address_space *vm =
 		ctx->ppgtt ? &ctx->ppgtt->base : &ctx->i915->ggtt.base;
 	u64 size;
 	u32 handle;
 	int err;

 	size = min(vm->total / 2, 1024ull * DW_PER_PAGE * PAGE_SIZE);
 	size = round_down(size, DW_PER_PAGE * PAGE_SIZE);

 	obj = huge_gem_object(ctx->i915, DW_PER_PAGE * PAGE_SIZE, size);
 	if (IS_ERR(obj))
 		return obj;

 	/* tie the handle to the drm_file for easy reaping */
 	err = drm_gem_handle_create(file, &obj->base, &handle);
 	i915_gem_object_put(obj);
 	if (err)
 		return ERR_PTR(err);

 	err = cpu_fill(obj, 0xdeadbeef);
 	if (err) {
 		pr_err("Failed to fill object with cpu, err=%d\n",
 		       err);
 		return ERR_PTR(err);
 	}

 	list_add_tail(&obj->st_link, objects);
 	return obj;
 }

 static unsigned long max_dwords(struct drm_i915_gem_object *obj)
 {
 	unsigned long npages = fake_page_count(obj);

 	GEM_BUG_ON(!IS_ALIGNED(npages, DW_PER_PAGE));
 	return npages / DW_PER_PAGE;
 }

 static int igt_ctx_exec(void *arg)
 {
 	struct drm_i915_private *i915 = arg;
 	struct drm_i915_gem_object *obj = NULL;
 	struct drm_file *file;
 	IGT_TIMEOUT(end_time);
 	LIST_HEAD(objects);
 	unsigned long ncontexts, ndwords, dw;
 	bool first_shared_gtt = true;
 	int err;

 	/* Create a few different contexts (with different mm) and write
 	 * through each ctx/mm using the GPU making sure those writes end
 	 * up in the expected pages of our obj.
 	 */

 	file = mock_file(i915);
 	if (IS_ERR(file))
 		return PTR_ERR(file);

 	mutex_lock(&i915->drm.struct_mutex);

 	ncontexts = 0;
 	ndwords = 0;
 	dw = 0;
 	while (!time_after(jiffies, end_time)) {
 		struct intel_engine_cs *engine;
 		struct i915_gem_context *ctx;
 		unsigned int id;

 		if (first_shared_gtt) {
 			ctx = __create_hw_context(i915, file->driver_priv);
 			first_shared_gtt = false;
 		} else {
 			ctx = i915_gem_create_context(i915, file->driver_priv);
 		}
 		if (IS_ERR(ctx)) {
 			err = PTR_ERR(ctx);
 			goto out_unlock;
 		}

 		for_each_engine(engine, i915, id) {
 			if (!obj) {
 				obj = create_test_object(ctx, file, &objects);
 				if (IS_ERR(obj)) {
 					err = PTR_ERR(obj);
 					goto out_unlock;
 				}
 			}

 			err = gpu_fill(obj, ctx, engine, dw);
 			if (err) {
 				pr_err("Failed to fill dword %lu [%lu/%lu] with gpu (%s) in ctx %u [full-ppgtt? %s], err=%d\n",
 				       ndwords, dw, max_dwords(obj),
 				       engine->name, ctx->hw_id,
 				       yesno(!!ctx->ppgtt), err);
 				goto out_unlock;
 			}

 			if (++dw == max_dwords(obj)) {
 				obj = NULL;
 				dw = 0;
 			}
 			ndwords++;
 		}
 		ncontexts++;
 	}
 	pr_info("Submitted %lu contexts (across %u engines), filling %lu dwords\n",
 		ncontexts, INTEL_INFO(i915)->num_rings, ndwords);

 	dw = 0;
 	list_for_each_entry(obj, &objects, st_link) {
 		unsigned int rem =
 			min_t(unsigned int, ndwords - dw, max_dwords(obj));

 		err = cpu_check(obj, rem);
 		if (err)
 			break;

 		dw += rem;
 	}

 out_unlock:
 	mutex_unlock(&i915->drm.struct_mutex);

 	mock_file_free(i915, file);
 	return err;
 }

 static int fake_aliasing_ppgtt_enable(struct drm_i915_private *i915)
 {
 	struct drm_i915_gem_object *obj;
 	int err;

 	err = i915_gem_init_aliasing_ppgtt(i915);
 	if (err)
 		return err;

 	list_for_each_entry(obj, &i915->mm.bound_list, global_link) {
 		struct i915_vma *vma;

 		vma = i915_vma_instance(obj, &i915->ggtt.base, NULL);
 		if (IS_ERR(vma))
 			continue;

 		vma->flags &= ~I915_VMA_LOCAL_BIND;
 	}

 	return 0;
 }

 static void fake_aliasing_ppgtt_disable(struct drm_i915_private *i915)
 {
 	i915_gem_fini_aliasing_ppgtt(i915);
 }

 int i915_gem_context_live_selftests(struct drm_i915_private *dev_priv)
 {
 	static const struct i915_subtest tests[] = {
 		SUBTEST(igt_ctx_exec),
 	};
 	bool fake_alias = false;
 	int err;

 	/* Install a fake aliasing gtt for exercise */
 	if (USES_PPGTT(dev_priv) && !dev_priv->mm.aliasing_ppgtt) {
 		mutex_lock(&dev_priv->drm.struct_mutex);
 		err = fake_aliasing_ppgtt_enable(dev_priv);
 		mutex_unlock(&dev_priv->drm.struct_mutex);
 		if (err)
 			return err;

 		GEM_BUG_ON(!dev_priv->mm.aliasing_ppgtt);
 		fake_alias = true;
 	}

 	err = i915_subtests(tests, dev_priv);

 	if (fake_alias) {
 		mutex_lock(&dev_priv->drm.struct_mutex);
 		fake_aliasing_ppgtt_disable(dev_priv);
 		mutex_unlock(&dev_priv->drm.struct_mutex);
 	}

 	return err;
 }
	/*
	* Copyright © 2017 Intel Corporation
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice (including the next
	* paragraph) shall be included in all copies or substantial portions of the
	* Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	* IN THE SOFTWARE.
	*
	*/

	#include "../i915_selftest.h"

	#include "mock_drm.h"
	#include "huge_gem_object.h"

	#define DW_PER_PAGE (PAGE_SIZE / sizeof(u32))

	static struct i915_vma *
	gpu_fill_dw(struct i915_vma *vma, u64 offset, unsigned long count, u32 value)
	{
	struct drm_i915_gem_object *obj;
	const int gen = INTEL_GEN(vma->vm->i915);
	unsigned long n, size;
	u32 *cmd;
	int err;

	GEM_BUG_ON(!igt_can_mi_store_dword_imm(vma->vm->i915));

	size = (4 * count + 1) * sizeof(u32);
	size = round_up(size, PAGE_SIZE);
	obj = i915_gem_object_create_internal(vma->vm->i915, size);
	if (IS_ERR(obj))
	return ERR_CAST(obj);

	cmd = i915_gem_object_pin_map(obj, I915_MAP_WB);
	if (IS_ERR(cmd)) {
	err = PTR_ERR(cmd);
	goto err;
	}

	GEM_BUG_ON(offset + (count - 1) * PAGE_SIZE > vma->node.size);
	offset += vma->node.start;

	for (n = 0; n < count; n++) {
	if (gen >= 8) {
	*cmd++ = MI_STORE_DWORD_IMM_GEN4;
	*cmd++ = lower_32_bits(offset);
	*cmd++ = upper_32_bits(offset);
	*cmd++ = value;
	} else if (gen >= 4) {
	*cmd++ = MI_STORE_DWORD_IMM_GEN4 \|
	(gen < 6 ? 1 << 22 : 0);
	*cmd++ = 0;
	*cmd++ = offset;
	*cmd++ = value;
	} else {
	*cmd++ = MI_STORE_DWORD_IMM \| 1 << 22;
	*cmd++ = offset;
	*cmd++ = value;
	}
	offset += PAGE_SIZE;
	}
	*cmd = MI_BATCH_BUFFER_END;
	i915_gem_object_unpin_map(obj);

	err = i915_gem_object_set_to_gtt_domain(obj, false);
	if (err)
	goto err;

	vma = i915_vma_instance(obj, vma->vm, NULL);
	if (IS_ERR(vma)) {
	err = PTR_ERR(vma);
	goto err;
	}

	err = i915_vma_pin(vma, 0, 0, PIN_USER);
	if (err)
	goto err;

	return vma;

	err:
	i915_gem_object_put(obj);
	return ERR_PTR(err);
	}

	static unsigned long real_page_count(struct drm_i915_gem_object *obj)
	{
	return huge_gem_object_phys_size(obj) >> PAGE_SHIFT;
	}

	static unsigned long fake_page_count(struct drm_i915_gem_object *obj)
	{
	return huge_gem_object_dma_size(obj) >> PAGE_SHIFT;
	}

	static int gpu_fill(struct drm_i915_gem_object *obj,
	struct i915_gem_context *ctx,
	struct intel_engine_cs *engine,
	unsigned int dw)
	{
	struct drm_i915_private *i915 = to_i915(obj->base.dev);
	struct i915_address_space *vm =
	ctx->ppgtt ? &ctx->ppgtt->base : &i915->ggtt.base;
	struct drm_i915_gem_request *rq;
	struct i915_vma *vma;
	struct i915_vma *batch;
	unsigned int flags;
	int err;

	GEM_BUG_ON(obj->base.size > vm->total);

	vma = i915_vma_instance(obj, vm, NULL);
	if (IS_ERR(vma))
	return PTR_ERR(vma);

	err = i915_gem_object_set_to_gtt_domain(obj, false);
	if (err)
	return err;

	err = i915_vma_pin(vma, 0, 0, PIN_HIGH \| PIN_USER);
	if (err)
	return err;

	/* Within the GTT the huge objects maps every page onto
	* its 1024 real pages (using phys_pfn = dma_pfn % 1024).
	* We set the nth dword within the page using the nth
	* mapping via the GTT - this should exercise the GTT mapping
	* whilst checking that each context provides a unique view
	* into the object.
	*/
	batch = gpu_fill_dw(vma,
	(dw * real_page_count(obj)) << PAGE_SHIFT \|
	(dw * sizeof(u32)),
	real_page_count(obj),
	dw);
	if (IS_ERR(batch)) {
	err = PTR_ERR(batch);
	goto err_vma;
	}

	rq = i915_gem_request_alloc(engine, ctx);
	if (IS_ERR(rq)) {
	err = PTR_ERR(rq);
	goto err_batch;
	}

	err = engine->emit_flush(rq, EMIT_INVALIDATE);
	if (err)
	goto err_request;

	err = i915_switch_context(rq);
	if (err)
	goto err_request;

	flags = 0;
	if (INTEL_GEN(vm->i915) <= 5)
	flags \|= I915_DISPATCH_SECURE;

	err = engine->emit_bb_start(rq,
	batch->node.start, batch->node.size,
	flags);
	if (err)
	goto err_request;

	i915_vma_move_to_active(batch, rq, 0);
	i915_gem_object_set_active_reference(batch->obj);
	i915_vma_unpin(batch);
	i915_vma_close(batch);

	i915_vma_move_to_active(vma, rq, 0);
	i915_vma_unpin(vma);

	reservation_object_lock(obj->resv, NULL);
	reservation_object_add_excl_fence(obj->resv, &rq->fence);
	reservation_object_unlock(obj->resv);

	__i915_add_request(rq, true);

	return 0;

	err_request:
	__i915_add_request(rq, false);
	err_batch:
	i915_vma_unpin(batch);
	err_vma:
	i915_vma_unpin(vma);
	return err;
	}

	static int cpu_fill(struct drm_i915_gem_object *obj, u32 value)
	{
	const bool has_llc = HAS_LLC(to_i915(obj->base.dev));
	unsigned int n, m, need_flush;
	int err;

	err = i915_gem_obj_prepare_shmem_write(obj, &need_flush);
	if (err)
	return err;

	for (n = 0; n < real_page_count(obj); n++) {
	u32 *map;

	map = kmap_atomic(i915_gem_object_get_page(obj, n));
	for (m = 0; m < DW_PER_PAGE; m++)
	map[m] = value;
	if (!has_llc)
	drm_clflush_virt_range(map, PAGE_SIZE);
	kunmap_atomic(map);
	}

	i915_gem_obj_finish_shmem_access(obj);
	obj->base.read_domains = I915_GEM_DOMAIN_GTT \| I915_GEM_DOMAIN_CPU;
	obj->base.write_domain = 0;
	return 0;
	}

	static int cpu_check(struct drm_i915_gem_object *obj, unsigned int max)
	{
	unsigned int n, m, needs_flush;
	int err;

	err = i915_gem_obj_prepare_shmem_read(obj, &needs_flush);
	if (err)
	return err;

	for (n = 0; n < real_page_count(obj); n++) {
	u32 *map;

	map = kmap_atomic(i915_gem_object_get_page(obj, n));
	if (needs_flush & CLFLUSH_BEFORE)
	drm_clflush_virt_range(map, PAGE_SIZE);

	for (m = 0; m < max; m++) {
	if (map[m] != m) {
	pr_err("Invalid value at page %d, offset %d: found %x expected %x\n",
	n, m, map[m], m);
	err = -EINVAL;
	goto out_unmap;
	}
	}

	for (; m < DW_PER_PAGE; m++) {
	if (map[m] != 0xdeadbeef) {
	pr_err("Invalid value at page %d, offset %d: found %x expected %x\n",
	n, m, map[m], 0xdeadbeef);
	err = -EINVAL;
	goto out_unmap;
	}
	}

	out_unmap:
	kunmap_atomic(map);
	if (err)
	break;
	}

	i915_gem_obj_finish_shmem_access(obj);
	return err;
	}

	static struct drm_i915_gem_object *
	create_test_object(struct i915_gem_context *ctx,
	struct drm_file *file,
	struct list_head *objects)
	{
	struct drm_i915_gem_object *obj;
	struct i915_address_space *vm =
	ctx->ppgtt ? &ctx->ppgtt->base : &ctx->i915->ggtt.base;
	u64 size;
	u32 handle;
	int err;

	size = min(vm->total / 2, 1024ull * DW_PER_PAGE * PAGE_SIZE);
	size = round_down(size, DW_PER_PAGE * PAGE_SIZE);

	obj = huge_gem_object(ctx->i915, DW_PER_PAGE * PAGE_SIZE, size);
	if (IS_ERR(obj))
	return obj;

	/* tie the handle to the drm_file for easy reaping */
	err = drm_gem_handle_create(file, &obj->base, &handle);
	i915_gem_object_put(obj);
	if (err)
	return ERR_PTR(err);

	err = cpu_fill(obj, 0xdeadbeef);
	if (err) {
	pr_err("Failed to fill object with cpu, err=%d\n",
	err);
	return ERR_PTR(err);
	}

	list_add_tail(&obj->st_link, objects);
	return obj;
	}

	static unsigned long max_dwords(struct drm_i915_gem_object *obj)
	{
	unsigned long npages = fake_page_count(obj);

	GEM_BUG_ON(!IS_ALIGNED(npages, DW_PER_PAGE));
	return npages / DW_PER_PAGE;
	}

	static int igt_ctx_exec(void *arg)
	{
	struct drm_i915_private *i915 = arg;
	struct drm_i915_gem_object *obj = NULL;
	struct drm_file *file;
	IGT_TIMEOUT(end_time);
	LIST_HEAD(objects);
	unsigned long ncontexts, ndwords, dw;
	bool first_shared_gtt = true;
	int err;

	/* Create a few different contexts (with different mm) and write
	* through each ctx/mm using the GPU making sure those writes end
	* up in the expected pages of our obj.
	*/

	file = mock_file(i915);
	if (IS_ERR(file))
	return PTR_ERR(file);

	mutex_lock(&i915->drm.struct_mutex);

	ncontexts = 0;
	ndwords = 0;
	dw = 0;
	while (!time_after(jiffies, end_time)) {
	struct intel_engine_cs *engine;
	struct i915_gem_context *ctx;
	unsigned int id;

	if (first_shared_gtt) {
	ctx = __create_hw_context(i915, file->driver_priv);
	first_shared_gtt = false;
	} else {
	ctx = i915_gem_create_context(i915, file->driver_priv);
	}
	if (IS_ERR(ctx)) {
	err = PTR_ERR(ctx);
	goto out_unlock;
	}

	for_each_engine(engine, i915, id) {
	if (!obj) {
	obj = create_test_object(ctx, file, &objects);
	if (IS_ERR(obj)) {
	err = PTR_ERR(obj);
	goto out_unlock;
	}
	}

	err = gpu_fill(obj, ctx, engine, dw);
	if (err) {
	pr_err("Failed to fill dword %lu [%lu/%lu] with gpu (%s) in ctx %u [full-ppgtt? %s], err=%d\n",
	ndwords, dw, max_dwords(obj),
	engine->name, ctx->hw_id,
	yesno(!!ctx->ppgtt), err);
	goto out_unlock;
	}

	if (++dw == max_dwords(obj)) {
	obj = NULL;
	dw = 0;
	}
	ndwords++;
	}
	ncontexts++;
	}
	pr_info("Submitted %lu contexts (across %u engines), filling %lu dwords\n",
	ncontexts, INTEL_INFO(i915)->num_rings, ndwords);

	dw = 0;
	list_for_each_entry(obj, &objects, st_link) {
	unsigned int rem =
	min_t(unsigned int, ndwords - dw, max_dwords(obj));

	err = cpu_check(obj, rem);
	if (err)
	break;

	dw += rem;
	}

	out_unlock:
	mutex_unlock(&i915->drm.struct_mutex);

	mock_file_free(i915, file);
	return err;
	}

	static int fake_aliasing_ppgtt_enable(struct drm_i915_private *i915)
	{
	struct drm_i915_gem_object *obj;
	int err;

	err = i915_gem_init_aliasing_ppgtt(i915);
	if (err)
	return err;

	list_for_each_entry(obj, &i915->mm.bound_list, global_link) {
	struct i915_vma *vma;

	vma = i915_vma_instance(obj, &i915->ggtt.base, NULL);
	if (IS_ERR(vma))
	continue;

	vma->flags &= ~I915_VMA_LOCAL_BIND;
	}

	return 0;
	}

	static void fake_aliasing_ppgtt_disable(struct drm_i915_private *i915)
	{
	i915_gem_fini_aliasing_ppgtt(i915);
	}

	int i915_gem_context_live_selftests(struct drm_i915_private *dev_priv)
	{
	static const struct i915_subtest tests[] = {
	SUBTEST(igt_ctx_exec),
	};
	bool fake_alias = false;
	int err;

	/* Install a fake aliasing gtt for exercise */
	if (USES_PPGTT(dev_priv) && !dev_priv->mm.aliasing_ppgtt) {
	mutex_lock(&dev_priv->drm.struct_mutex);
	err = fake_aliasing_ppgtt_enable(dev_priv);
	mutex_unlock(&dev_priv->drm.struct_mutex);
	if (err)
	return err;

	GEM_BUG_ON(!dev_priv->mm.aliasing_ppgtt);
	fake_alias = true;
	}

	err = i915_subtests(tests, dev_priv);

	if (fake_alias) {
	mutex_lock(&dev_priv->drm.struct_mutex);
	fake_aliasing_ppgtt_disable(dev_priv);
	mutex_unlock(&dev_priv->drm.struct_mutex);
	}

	return err;
	}