[PATCH 6/6] drm/i915: Migrate stolen objects before hibernation

[ankitprasad.r.sharma@intel.com]

From: Chris Wilson <chris@chris-wilson.co.uk>

Ville reminded us that stolen memory is not preserved across
hibernation, and a result of this was that context objects now being
allocated from stolen were being corrupted on S4 and promptly hanging
the GPU on resume.

We want to utilise stolen for as much as possible (nothing else will use
that wasted memory otherwise), so we need a strategy for handling
general objects allocated from stolen and hibernation. A simple solution
is to do a CPU copy through the GTT of the stolen object into a fresh
shmemfs backing store and thenceforth treat it as a normal objects. This
can be refined in future to either use a GPU copy to avoid the slow
uncached reads (though it's hibernation!) and recreate stolen objects
upon resume/first-use. For now, a simple approach should suffice for
testing the object migration.

v2:
Swap PTE for pinned bindings over to the shmemfs. This adds a
complicated dance, but is required as many stolen objects are likely to
be pinned for use by the hardware. Swapping the PTEs should not result
in externally visible behaviour, as each PTE update should be atomic and
the two pages identical. (danvet)

safe-by-default, or the principle of least surprise. We need a new flag
to mark objects that we can wilfully discard and recreate across
hibernation. (danvet)

Just use the global_list rather than invent a new stolen_list. This is
the slowpath hibernate and so adding a new list and the associated
complexity isn't worth it.

v3: Rebased on drm-intel-nightly (Ankit)

v4: Use insert_page to map stolen memory backed pages for migration to
shmem (Chris)

v5: Acquire mutex lock while copying stolen buffer objects to shmem (Chris)

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c         |  17 ++-
 drivers/gpu/drm/i915/i915_drv.h         |   7 +
 drivers/gpu/drm/i915/i915_gem.c         | 232 ++++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/intel_display.c    |   3 +
 drivers/gpu/drm/i915/intel_fbdev.c      |   6 +
 drivers/gpu/drm/i915/intel_pm.c         |   2 +
 drivers/gpu/drm/i915/intel_ringbuffer.c |   6 +
 7 files changed, 261 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 9f55209..2bb9e9e 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1036,6 +1036,21 @@ static int i915_pm_suspend(struct device *dev)
 	return i915_drm_suspend(drm_dev);
 }
 
+static int i915_pm_freeze(struct device *dev)
+{
+	int ret;
+
+	ret = i915_gem_freeze(pci_get_drvdata(to_pci_dev(dev)));
+	if (ret)
+		return ret;
+
+	ret = i915_pm_suspend(dev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static int i915_pm_suspend_late(struct device *dev)
 {
 	struct drm_device *drm_dev = dev_to_i915(dev)->dev;
@@ -1700,7 +1715,7 @@ static const struct dev_pm_ops i915_pm_ops = {
 	 * @restore, @restore_early : called after rebooting and restoring the
 	 *                            hibernation image [PMSG_RESTORE]
 	 */
-	.freeze = i915_pm_suspend,
+	.freeze = i915_pm_freeze,
 	.freeze_late = i915_pm_suspend_late,
 	.thaw_early = i915_pm_resume_early,
 	.thaw = i915_pm_resume,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e0b09b0..0d18b07 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2080,6 +2080,12 @@ struct drm_i915_gem_object {
 	 * Advice: are the backing pages purgeable?
 	 */
 	unsigned int madv:2;
+	/**
+	 * Whereas madv is for userspace, there are certain situations
+	 * where we want I915_MADV_DONTNEED behaviour on internal objects
+	 * without conflating the userspace setting.
+	 */
+	unsigned int internal_volatile:1;
 
 	/**
 	 * Current tiling mode for the object.
@@ -3006,6 +3012,7 @@ int i915_gem_l3_remap(struct drm_i915_gem_request *req, int slice);
 void i915_gem_init_swizzling(struct drm_device *dev);
 void i915_gem_cleanup_ringbuffer(struct drm_device *dev);
 int __must_check i915_gpu_idle(struct drm_device *dev);
+int __must_check i915_gem_freeze(struct drm_device *dev);
 int __must_check i915_gem_suspend(struct drm_device *dev);
 void __i915_add_request(struct drm_i915_gem_request *req,
 			struct drm_i915_gem_object *batch_obj,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 68ed67a..1f134b0 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4511,12 +4511,27 @@ static const struct drm_i915_gem_object_ops i915_gem_object_ops = {
 	.put_pages = i915_gem_object_put_pages_gtt,
 };
 
+static struct address_space *
+i915_gem_set_inode_gfp(struct drm_device *dev, struct file *file)
+{
+	struct address_space *mapping = file_inode(file)->i_mapping;
+	gfp_t mask;
+
+	mask = GFP_HIGHUSER | __GFP_RECLAIMABLE;
+	if (IS_CRESTLINE(dev) || IS_BROADWATER(dev)) {
+		/* 965gm cannot relocate objects above 4GiB. */
+		mask &= ~__GFP_HIGHMEM;
+		mask |= __GFP_DMA32;
+	}
+	mapping_set_gfp_mask(mapping, mask);
+
+	return mapping;
+}
+
 struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
 						  size_t size)
 {
 	struct drm_i915_gem_object *obj;
-	struct address_space *mapping;
-	gfp_t mask;
 	int ret;
 
 	obj = i915_gem_object_alloc(dev);
@@ -4529,15 +4544,7 @@ struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
 		return ERR_PTR(ret);
 	}
 
-	mask = GFP_HIGHUSER | __GFP_RECLAIMABLE;
-	if (IS_CRESTLINE(dev) || IS_BROADWATER(dev)) {
-		/* 965gm cannot relocate objects above 4GiB. */
-		mask &= ~__GFP_HIGHMEM;
-		mask |= __GFP_DMA32;
-	}
-
-	mapping = file_inode(obj->base.filp)->i_mapping;
-	mapping_set_gfp_mask(mapping, mask);
+	i915_gem_set_inode_gfp(dev, obj->base.filp);
 
 	i915_gem_object_init(obj, &i915_gem_object_ops);
 
@@ -4714,6 +4721,209 @@ i915_gem_stop_ringbuffers(struct drm_device *dev)
 		dev_priv->gt.stop_ring(ring);
 }
 
+static int
+i915_gem_object_migrate_stolen_to_shmemfs(struct drm_i915_gem_object *obj)
+{
+	struct drm_i915_private *i915 = to_i915(obj->base.dev);
+	struct i915_vma *vma, *vn;
+	struct drm_mm_node node;
+	struct file *file;
+	struct address_space *mapping;
+	struct sg_table *stolen_pages, *shmemfs_pages;
+	int ret, i;
+
+	if (WARN_ON(i915_gem_object_needs_bit17_swizzle(obj)))
+		return -EINVAL;
+
+	ret = i915_gem_object_set_to_gtt_domain(obj, false);
+	if (ret)
+		return ret;
+
+	file = shmem_file_setup("drm mm object", obj->base.size, VM_NORESERVE);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+	mapping = i915_gem_set_inode_gfp(obj->base.dev, file);
+
+	list_for_each_entry_safe(vma, vn, &obj->vma_list, vma_link)
+		if (i915_vma_unbind(vma))
+			continue;
+
+	if (obj->madv != I915_MADV_WILLNEED && list_empty(&obj->vma_list)) {
+		/* Discard the stolen reservation, and replace with
+		 * an unpopulated shmemfs object.
+		 */
+		obj->madv = __I915_MADV_PURGED;
+		goto swap_pages;
+	}
+
+	/* stolen objects are already pinned to prevent shrinkage */
+	memset(&node, 0, sizeof(node));
+	ret = drm_mm_insert_node_in_range_generic(&i915->gtt.base.mm,
+						  &node,
+						  4096, 0, I915_CACHE_NONE,
+						  0, i915->gtt.mappable_end,
+						  DRM_MM_SEARCH_DEFAULT,
+						  DRM_MM_CREATE_DEFAULT);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
+		struct page *page;
+		void *__iomem src;
+		void *dst;
+
+		wmb();
+		i915->gtt.base.insert_page(&i915->gtt.base,
+					   i915_gem_object_get_dma_address(obj, i),
+					   node.start,
+					   I915_CACHE_NONE,
+					   0);
+		wmb();
+
+		page = shmem_read_mapping_page(mapping, i);
+		if (IS_ERR(page)) {
+			ret = PTR_ERR(page);
+			goto err_node;
+		}
+
+		src = io_mapping_map_atomic_wc(i915->gtt.mappable, node.start + PAGE_SIZE * i);
+		dst = kmap_atomic(page);
+		memcpy_fromio(dst, src, PAGE_SIZE);
+		kunmap_atomic(dst);
+		io_mapping_unmap_atomic(src);
+
+		page_cache_release(page);
+	}
+
+	wmb();
+	i915->gtt.base.clear_range(&i915->gtt.base,
+				   node.start, node.size,
+				   true);
+	drm_mm_remove_node(&node);
+
+swap_pages:
+	stolen_pages = obj->pages;
+	obj->pages = NULL;
+
+	obj->base.filp = file;
+	obj->base.read_domains = I915_GEM_DOMAIN_CPU;
+	obj->base.write_domain = I915_GEM_DOMAIN_CPU;
+
+	/* Recreate any pinned binding with pointers to the new storage */
+	if (!list_empty(&obj->vma_list)) {
+		ret = i915_gem_object_get_pages_gtt(obj);
+		if (ret) {
+			obj->pages = stolen_pages;
+			goto err_file;
+		}
+
+		ret = i915_gem_object_set_to_gtt_domain(obj, true);
+		if (ret) {
+			i915_gem_object_put_pages_gtt(obj);
+			obj->pages = stolen_pages;
+			goto err_file;
+		}
+
+		obj->get_page.sg = obj->pages->sgl;
+		obj->get_page.last = 0;
+
+		list_for_each_entry(vma, &obj->vma_list, vma_link) {
+			if (!drm_mm_node_allocated(&vma->node))
+				continue;
+
+			WARN_ON(i915_vma_bind(vma,
+					      obj->cache_level,
+					      PIN_UPDATE));
+		}
+	} else
+		list_del(&obj->global_list);
+
+	/* drop the stolen pin and backing */
+	shmemfs_pages = obj->pages;
+	obj->pages = stolen_pages;
+
+	i915_gem_object_unpin_pages(obj);
+	obj->ops->put_pages(obj);
+	if (obj->ops->release)
+		obj->ops->release(obj);
+
+	obj->ops = &i915_gem_object_ops;
+	obj->pages = shmemfs_pages;
+
+	return 0;
+
+err_node:
+	wmb();
+	i915->gtt.base.clear_range(&i915->gtt.base,
+				   node.start, node.size,
+				   true);
+	drm_mm_remove_node(&node);
+err_file:
+	fput(file);
+	obj->base.filp = NULL;
+	return ret;
+}
+
+int
+i915_gem_freeze(struct drm_device *dev)
+{
+	/* Called before i915_gem_suspend() when hibernating */
+	struct drm_i915_private *i915 = to_i915(dev);
+	struct drm_i915_gem_object *obj, *tmp;
+	struct list_head *phase[] = {
+		&i915->mm.unbound_list, &i915->mm.bound_list, NULL
+	}, **p;
+	int ret;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ret;
+	/* Across hibernation, the stolen area is not preserved.
+	 * Anything inside stolen must copied back to normal
+	 * memory if we wish to preserve it.
+	 */
+	for (p = phase; *p; p++) {
+		struct list_head migrate;
+		int ret;
+
+		INIT_LIST_HEAD(&migrate);
+		list_for_each_entry_safe(obj, tmp, *p, global_list) {
+			if (obj->stolen == NULL)
+				continue;
+
+			if (obj->internal_volatile)
+				continue;
+
+			/* In the general case, this object may only be alive
+			 * due to an active reference, and that may disappear
+			 * when we unbind any of the objects (and so wait upon
+			 * the GPU and retire requests). To prevent one of the
+			 * objects from disappearing beneath us, we need to
+			 * take a reference to each as we build the migration
+			 * list.
+			 *
+			 * This is similar to the strategy required whilst
+			 * shrinking or evicting objects (for the same reason).
+			 */
+			drm_gem_object_reference(&obj->base);
+			list_move(&obj->global_list, &migrate);
+		}
+
+		ret = 0;
+		list_for_each_entry_safe(obj, tmp, &migrate, global_list) {
+			if (ret == 0)
+				ret = i915_gem_object_migrate_stolen_to_shmemfs(obj);
+			drm_gem_object_unreference(&obj->base);
+		}
+		list_splice(&migrate, *p);
+		if (ret)
+			break;
+	}
+
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
+}
+
 int
 i915_gem_suspend(struct drm_device *dev)
 {
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f281e0b..0803922 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2549,6 +2549,9 @@ intel_alloc_initial_plane_obj(struct intel_crtc *crtc,
 	if (IS_ERR(obj))
 		return false;
 
+	/* Not to be preserved across hibernation */
+	obj->internal_volatile = true;
+
 	obj->tiling_mode = plane_config->tiling;
 	if (obj->tiling_mode == I915_TILING_X)
 		obj->stride = fb->pitches[0];
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index f43681e..1d89253 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -154,6 +154,12 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
 		goto out;
 	}
 
+	/* Discard the contents of the BIOS fb across hibernation.
+	 * We really want to completely throwaway the earlier fbdev
+	 * and reconfigure it anyway.
+	 */
+	obj->internal_volatile = true;
+
 	fb = __intel_framebuffer_create(dev, &mode_cmd, obj);
 	if (IS_ERR(fb)) {
 		ret = PTR_ERR(fb);
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 03ad276..6ddc20a 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5181,6 +5181,8 @@ static void valleyview_setup_pctx(struct drm_device *dev)
 	I915_WRITE(VLV_PCBR, pctx_paddr);
 
 out:
+	/* The power context need not be preserved across hibernation */
+	pctx->internal_volatile = true;
 	DRM_DEBUG_DRIVER("PCBR: 0x%08x\n", I915_READ(VLV_PCBR));
 	dev_priv->vlv_pctx = pctx;
 }
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 5eabaf6..370d96a 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2090,6 +2090,12 @@ static int intel_alloc_ringbuffer_obj(struct drm_device *dev,
 	if (IS_ERR(obj))
 		return PTR_ERR(obj);
 
+	/* Ringbuffer objects are by definition volatile - only the commands
+	 * between HEAD and TAIL need to be preserved and whilst there are
+	 * any commands there, the ringbuffer is pinned by activity.
+	 */
+	obj->internal_volatile = true;
+
 	/* mark ring buffers as read-only from GPU side by default */
 	obj->gt_ro = 1;
 
-- 
1.9.1

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