i915_gem_object.c

/*
 * 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_drv.h"
#include "i915_gem_clflush.h"
#include "i915_gem_context.h"
#include "i915_gem_object.h"
#include "i915_globals.h"
#include "intel_frontbuffer.h"

static struct i915_global_object {
	struct i915_global base;
	struct kmem_cache *slab_objects;
} global;

struct drm_i915_gem_object *i915_gem_object_alloc(void)
{
	return kmem_cache_zalloc(global.slab_objects, GFP_KERNEL);
}

void i915_gem_object_free(struct drm_i915_gem_object *obj)
{
	return kmem_cache_free(global.slab_objects, obj);
}

/* some bookkeeping */
static void i915_gem_info_add_obj(struct drm_i915_private *i915,
				  u64 size)
{
	spin_lock(&i915->mm.object_stat_lock);
	i915->mm.object_count++;
	i915->mm.object_memory += size;
	spin_unlock(&i915->mm.object_stat_lock);
}

static void i915_gem_info_remove_obj(struct drm_i915_private *i915,
				     u64 size)
{
	spin_lock(&i915->mm.object_stat_lock);
	i915->mm.object_count--;
	i915->mm.object_memory -= size;
	spin_unlock(&i915->mm.object_stat_lock);
}

static void
frontbuffer_retire(struct i915_active_request *active,
		   struct i915_request *request)
{
	struct drm_i915_gem_object *obj =
		container_of(active, typeof(*obj), frontbuffer_write);

	intel_fb_obj_flush(obj, ORIGIN_CS);
}

void i915_gem_object_init(struct drm_i915_gem_object *obj,
			  const struct drm_i915_gem_object_ops *ops)
{
	mutex_init(&obj->mm.lock);

	spin_lock_init(&obj->vma.lock);
	INIT_LIST_HEAD(&obj->vma.list);

	INIT_LIST_HEAD(&obj->lut_list);
	INIT_LIST_HEAD(&obj->batch_pool_link);

	init_rcu_head(&obj->rcu);

	obj->ops = ops;

	reservation_object_init(&obj->__builtin_resv);
	obj->resv = &obj->__builtin_resv;

	obj->frontbuffer_ggtt_origin = ORIGIN_GTT;
	i915_active_request_init(&obj->frontbuffer_write,
				 NULL, frontbuffer_retire);

	obj->mm.madv = I915_MADV_WILLNEED;
	INIT_RADIX_TREE(&obj->mm.get_page.radix, GFP_KERNEL | __GFP_NOWARN);
	mutex_init(&obj->mm.get_page.lock);

	i915_gem_info_add_obj(to_i915(obj->base.dev), obj->base.size);
}

/**
 * Mark up the object's coherency levels for a given cache_level
 * @obj: #drm_i915_gem_object
 * @cache_level: cache level
 */
void i915_gem_object_set_cache_coherency(struct drm_i915_gem_object *obj,
					 unsigned int cache_level)
{
	obj->cache_level = cache_level;

	if (cache_level != I915_CACHE_NONE)
		obj->cache_coherent = (I915_BO_CACHE_COHERENT_FOR_READ |
				       I915_BO_CACHE_COHERENT_FOR_WRITE);
	else if (HAS_LLC(to_i915(obj->base.dev)))
		obj->cache_coherent = I915_BO_CACHE_COHERENT_FOR_READ;
	else
		obj->cache_coherent = 0;

	obj->cache_dirty =
		!(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_WRITE);
}

void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
{
	struct drm_i915_private *i915 = to_i915(gem->dev);
	struct drm_i915_gem_object *obj = to_intel_bo(gem);
	struct drm_i915_file_private *fpriv = file->driver_priv;
	struct i915_lut_handle *lut, *ln;

	mutex_lock(&i915->drm.struct_mutex);

	list_for_each_entry_safe(lut, ln, &obj->lut_list, obj_link) {
		struct i915_gem_context *ctx = lut->ctx;
		struct i915_vma *vma;

		GEM_BUG_ON(ctx->file_priv == ERR_PTR(-EBADF));
		if (ctx->file_priv != fpriv)
			continue;

		vma = radix_tree_delete(&ctx->handles_vma, lut->handle);
		GEM_BUG_ON(vma->obj != obj);

		/* We allow the process to have multiple handles to the same
		 * vma, in the same fd namespace, by virtue of flink/open.
		 */
		GEM_BUG_ON(!vma->open_count);
		if (!--vma->open_count && !i915_vma_is_ggtt(vma))
			i915_vma_close(vma);

		list_del(&lut->obj_link);
		list_del(&lut->ctx_link);

		i915_lut_handle_free(lut);
		__i915_gem_object_release_unless_active(obj);
	}

	mutex_unlock(&i915->drm.struct_mutex);
}

static bool discard_backing_storage(struct drm_i915_gem_object *obj)
{
	/* If we are the last user of the backing storage (be it shmemfs
	 * pages or stolen etc), we know that the pages are going to be
	 * immediately released. In this case, we can then skip copying
	 * back the contents from the GPU.
	 */

	if (obj->mm.madv != I915_MADV_WILLNEED)
		return false;

	if (!obj->base.filp)
		return true;

	/* At first glance, this looks racy, but then again so would be
	 * userspace racing mmap against close. However, the first external
	 * reference to the filp can only be obtained through the
	 * i915_gem_mmap_ioctl() which safeguards us against the user
	 * acquiring such a reference whilst we are in the middle of
	 * freeing the object.
	 */
	return file_count(obj->base.filp) == 1;
}

static void __i915_gem_free_objects(struct drm_i915_private *i915,
				    struct llist_node *freed)
{
	struct drm_i915_gem_object *obj, *on;
	intel_wakeref_t wakeref;

	wakeref = intel_runtime_pm_get(i915);
	llist_for_each_entry_safe(obj, on, freed, freed) {
		struct i915_vma *vma, *vn;

		trace_i915_gem_object_destroy(obj);

		mutex_lock(&i915->drm.struct_mutex);

		GEM_BUG_ON(i915_gem_object_is_active(obj));
		list_for_each_entry_safe(vma, vn, &obj->vma.list, obj_link) {
			GEM_BUG_ON(i915_vma_is_active(vma));
			vma->flags &= ~I915_VMA_PIN_MASK;
			i915_vma_destroy(vma);
		}
		GEM_BUG_ON(!list_empty(&obj->vma.list));
		GEM_BUG_ON(!RB_EMPTY_ROOT(&obj->vma.tree));

		/* This serializes freeing with the shrinker. Since the free
		 * is delayed, first by RCU then by the workqueue, we want the
		 * shrinker to be able to free pages of unreferenced objects,
		 * or else we may oom whilst there are plenty of deferred
		 * freed objects.
		 */
		if (i915_gem_object_has_pages(obj)) {
			spin_lock(&i915->mm.obj_lock);
			list_del_init(&obj->mm.link);
			spin_unlock(&i915->mm.obj_lock);
		}

		mutex_unlock(&i915->drm.struct_mutex);

		GEM_BUG_ON(obj->bind_count);
		GEM_BUG_ON(obj->userfault_count);
		GEM_BUG_ON(atomic_read(&obj->frontbuffer_bits));
		GEM_BUG_ON(!list_empty(&obj->lut_list));

		if (obj->ops->release)
			obj->ops->release(obj);

		if (WARN_ON(i915_gem_object_has_pinned_pages(obj)))
			atomic_set(&obj->mm.pages_pin_count, 0);
		__i915_gem_object_put_pages(obj, I915_MM_NORMAL);
		GEM_BUG_ON(i915_gem_object_has_pages(obj));

		if (obj->base.import_attach)
			drm_prime_gem_destroy(&obj->base, NULL);

		reservation_object_fini(&obj->__builtin_resv);
		drm_gem_object_release(&obj->base);
		i915_gem_info_remove_obj(i915, obj->base.size);

		bitmap_free(obj->bit_17);
		i915_gem_object_free(obj);

		GEM_BUG_ON(!atomic_read(&i915->mm.free_count));
		atomic_dec(&i915->mm.free_count);

		if (on)
			cond_resched();
	}
	intel_runtime_pm_put(i915, wakeref);
}

void i915_gem_flush_free_objects(struct drm_i915_private *i915)
{
	struct llist_node *freed;

	/* Free the oldest, most stale object to keep the free_list short */
	freed = NULL;
	if (!llist_empty(&i915->mm.free_list)) { /* quick test for hotpath */
		/* Only one consumer of llist_del_first() allowed */
		spin_lock(&i915->mm.free_lock);
		freed = llist_del_first(&i915->mm.free_list);
		spin_unlock(&i915->mm.free_lock);
	}
	if (unlikely(freed)) {
		freed->next = NULL;
		__i915_gem_free_objects(i915, freed);
	}
}

static void __i915_gem_free_work(struct work_struct *work)
{
	struct drm_i915_private *i915 =
		container_of(work, struct drm_i915_private, mm.free_work);
	struct llist_node *freed;

	/*
	 * All file-owned VMA should have been released by this point through
	 * i915_gem_close_object(), or earlier by i915_gem_context_close().
	 * However, the object may also be bound into the global GTT (e.g.
	 * older GPUs without per-process support, or for direct access through
	 * the GTT either for the user or for scanout). Those VMA still need to
	 * unbound now.
	 */

	spin_lock(&i915->mm.free_lock);
	while ((freed = llist_del_all(&i915->mm.free_list))) {
		spin_unlock(&i915->mm.free_lock);

		__i915_gem_free_objects(i915, freed);
		if (need_resched())
			return;

		spin_lock(&i915->mm.free_lock);
	}
	spin_unlock(&i915->mm.free_lock);
}

static void __i915_gem_free_object_rcu(struct rcu_head *head)
{
	struct drm_i915_gem_object *obj =
		container_of(head, typeof(*obj), rcu);
	struct drm_i915_private *i915 = to_i915(obj->base.dev);

	/*
	 * We reuse obj->rcu for the freed list, so we had better not treat
	 * it like a rcu_head from this point forwards. And we expect all
	 * objects to be freed via this path.
	 */
	destroy_rcu_head(&obj->rcu);

	/*
	 * Since we require blocking on struct_mutex to unbind the freed
	 * object from the GPU before releasing resources back to the
	 * system, we can not do that directly from the RCU callback (which may
	 * be a softirq context), but must instead then defer that work onto a
	 * kthread. We use the RCU callback rather than move the freed object
	 * directly onto the work queue so that we can mix between using the
	 * worker and performing frees directly from subsequent allocations for
	 * crude but effective memory throttling.
	 */
	if (llist_add(&obj->freed, &i915->mm.free_list))
		queue_work(i915->wq, &i915->mm.free_work);
}

void i915_gem_free_object(struct drm_gem_object *gem_obj)
{
	struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);

	if (obj->mm.quirked)
		__i915_gem_object_unpin_pages(obj);

	if (discard_backing_storage(obj))
		obj->mm.madv = I915_MADV_DONTNEED;

	/*
	 * Before we free the object, make sure any pure RCU-only
	 * read-side critical sections are complete, e.g.
	 * i915_gem_busy_ioctl(). For the corresponding synchronized
	 * lookup see i915_gem_object_lookup_rcu().
	 */
	atomic_inc(&to_i915(obj->base.dev)->mm.free_count);
	call_rcu(&obj->rcu, __i915_gem_free_object_rcu);
}

void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj)
{
	lockdep_assert_held(&obj->base.dev->struct_mutex);

	if (!i915_gem_object_has_active_reference(obj) &&
	    i915_gem_object_is_active(obj))
		i915_gem_object_set_active_reference(obj);
	else
		i915_gem_object_put(obj);
}

static inline enum fb_op_origin
fb_write_origin(struct drm_i915_gem_object *obj, unsigned int domain)
{
	return (domain == I915_GEM_DOMAIN_GTT ?
		obj->frontbuffer_ggtt_origin : ORIGIN_CPU);
}

static bool gpu_write_needs_clflush(struct drm_i915_gem_object *obj)
{
	return !(obj->cache_level == I915_CACHE_NONE ||
		 obj->cache_level == I915_CACHE_WT);
}

void
i915_gem_object_flush_write_domain(struct drm_i915_gem_object *obj,
				   unsigned int flush_domains)
{
	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
	struct i915_vma *vma;

	if (!(obj->write_domain & flush_domains))
		return;

	switch (obj->write_domain) {
	case I915_GEM_DOMAIN_GTT:
		i915_gem_flush_ggtt_writes(dev_priv);

		intel_fb_obj_flush(obj,
				   fb_write_origin(obj, I915_GEM_DOMAIN_GTT));

		for_each_ggtt_vma(vma, obj) {
			if (vma->iomap)
				continue;

			i915_vma_unset_ggtt_write(vma);
		}
		break;

	case I915_GEM_DOMAIN_WC:
		wmb();
		break;

	case I915_GEM_DOMAIN_CPU:
		i915_gem_clflush_object(obj, I915_CLFLUSH_SYNC);
		break;

	case I915_GEM_DOMAIN_RENDER:
		if (gpu_write_needs_clflush(obj))
			obj->cache_dirty = true;
		break;
	}

	obj->write_domain = 0;
}

void i915_gem_init__objects(struct drm_i915_private *i915)
{
	INIT_WORK(&i915->mm.free_work, __i915_gem_free_work);
}

static void i915_global_objects_shrink(void)
{
	kmem_cache_shrink(global.slab_objects);
}

static void i915_global_objects_exit(void)
{
	kmem_cache_destroy(global.slab_objects);
}

static struct i915_global_object global = { {
	.shrink = i915_global_objects_shrink,
	.exit = i915_global_objects_exit,
} };

int __init i915_global_objects_init(void)
{
	global.slab_objects =
		KMEM_CACHE(drm_i915_gem_object, SLAB_HWCACHE_ALIGN);
	if (!global.slab_objects)
		return -ENOMEM;

	i915_global_register(&global.base);
	return 0;
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/huge_gem_object.c"
#include "selftests/huge_pages.c"
#include "selftests/i915_gem_object.c"
#include "selftests/i915_gem_coherency.c"
#endif