drm/i915: Replace the array of pages with a scatterlist

Rather than have multiple data structures for describing our page layout
in conjunction with the array of pages, we can migrate all users over to
a scatterlist.

One major advantage, other than unifying the page tracking structures,
this offers is that we replace the vmalloc'ed array (which can be up to
a megabyte in size) with a chain of individual pages which helps reduce
memory pressure.

The disadvantage is that we then do not have a simple array to iterate,
or to access randomly. The common case for this is in the relocation
processing, which will typically fit within a single scatterlist page
and so be almost the same cost as the simple array. For iterating over
the array, the extra function call could be optimised away, but in
reality is an insignificant cost of either binding the pages, or
performing the pwrite/pread.

v2: Fix drm_clflush_sg() to not invoke wbinvd as well! And fix the
trivial compile error from rebasing.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

9 files changed, 214 insertions, 183 deletions

diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index 3dbc7f17eb1..4a4274b348b 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -101,6 +101,31 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
 EXPORT_SYMBOL(drm_clflush_pages);
 
 void
+drm_clflush_sg(struct sg_table *st)
+{
+#if defined(CONFIG_X86)
+	if (cpu_has_clflush) {
+		struct scatterlist *sg;
+		int i;
+
+		mb();
+		for_each_sg(st->sgl, sg, st->nents, i)
+			drm_clflush_page(sg_page(sg));
+		mb();
+
+		return;
+	}
+
+	if (on_each_cpu(drm_clflush_ipi_handler, NULL, 1) != 0)
+		printk(KERN_ERR "Timed out waiting for cache flush.\n");
+#else
+	printk(KERN_ERR "Architecture has no drm_cache.c support\n");
+	WARN_ON_ONCE(1);
+#endif
+}
+EXPORT_SYMBOL(drm_clflush_sg);
+
+void
 drm_clflush_virt_range(char *addr, unsigned long length)
 {
 #if defined(CONFIG_X86)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 12a075747dc..1d7502faebd 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1006,16 +1006,11 @@ struct drm_i915_gem_object {
 
 	unsigned int has_aliasing_ppgtt_mapping:1;
 	unsigned int has_global_gtt_mapping:1;
+	unsigned int has_dma_mapping:1;
 
-	struct page **pages;
+	struct sg_table *pages;
 	int pages_pin_count;
 
-	/**
-	 * DMAR support
-	 */
-	struct scatterlist *sg_list;
-	int num_sg;
-
 	/* prime dma-buf support */
 	struct sg_table *sg_table;
 	void *dma_buf_vmapping;
@@ -1342,6 +1337,15 @@ void i915_gem_release_mmap(struct drm_i915_gem_object *obj);
 void i915_gem_lastclose(struct drm_device *dev);
 
 int __must_check i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
+static inline struct page *i915_gem_object_get_page(struct drm_i915_gem_object *obj, int n)
+{
+	struct scatterlist *sg = obj->pages->sgl;
+	while (n >= SG_MAX_SINGLE_ALLOC) {
+		sg = sg_chain_ptr(sg + SG_MAX_SINGLE_ALLOC - 1);
+		n -= SG_MAX_SINGLE_ALLOC - 1;
+	}
+	return sg_page(sg+n);
+}
 static inline void i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
 {
 	BUG_ON(obj->pages == NULL);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 26c8bf9c5fa..8f001fa155a 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -411,6 +411,8 @@ i915_gem_shmem_pread(struct drm_device *dev,
 	int hit_slowpath = 0;
 	int prefaulted = 0;
 	int needs_clflush = 0;
+	struct scatterlist *sg;
+	int i;
 
 	user_data = (char __user *) (uintptr_t) args->data_ptr;
 	remain = args->size;
@@ -439,9 +441,15 @@ i915_gem_shmem_pread(struct drm_device *dev,
 
 	offset = args->offset;
 
-	while (remain > 0) {
+	for_each_sg(obj->pages->sgl, sg, obj->pages->nents, i) {
 		struct page *page;
 
+		if (i < offset >> PAGE_SHIFT)
+			continue;
+
+		if (remain <= 0)
+			break;
+
 		/* Operation in this page
 		 *
 		 * shmem_page_offset = offset within page in shmem file
@@ -452,7 +460,7 @@ i915_gem_shmem_pread(struct drm_device *dev,
 		if ((shmem_page_offset + page_length) > PAGE_SIZE)
 			page_length = PAGE_SIZE - shmem_page_offset;
 
-		page = obj->pages[offset >> PAGE_SHIFT];
+		page = sg_page(sg);
 		page_do_bit17_swizzling = obj_do_bit17_swizzling &&
 			(page_to_phys(page) & (1 << 17)) != 0;
 
@@ -731,6 +739,8 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
 	int hit_slowpath = 0;
 	int needs_clflush_after = 0;
 	int needs_clflush_before = 0;
+	int i;
+	struct scatterlist *sg;
 
 	user_data = (char __user *) (uintptr_t) args->data_ptr;
 	remain = args->size;
@@ -765,10 +775,16 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
 	offset = args->offset;
 	obj->dirty = 1;
 
-	while (remain > 0) {
+	for_each_sg(obj->pages->sgl, sg, obj->pages->nents, i) {
 		struct page *page;
 		int partial_cacheline_write;
 
+		if (i < offset >> PAGE_SHIFT)
+			continue;
+
+		if (remain <= 0)
+			break;
+
 		/* Operation in this page
 		 *
 		 * shmem_page_offset = offset within page in shmem file
@@ -787,7 +803,7 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
 			((shmem_page_offset | page_length)
 				& (boot_cpu_data.x86_clflush_size - 1));
 
-		page = obj->pages[offset >> PAGE_SHIFT];
+		page = sg_page(sg);
 		page_do_bit17_swizzling = obj_do_bit17_swizzling &&
 			(page_to_phys(page) & (1 << 17)) != 0;
 
@@ -1633,6 +1649,7 @@ static void
 i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
 {
 	int page_count = obj->base.size / PAGE_SIZE;
+	struct scatterlist *sg;
 	int ret, i;
 
 	BUG_ON(obj->madv == __I915_MADV_PURGED);
@@ -1653,19 +1670,21 @@ i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
 	if (obj->madv == I915_MADV_DONTNEED)
 		obj->dirty = 0;
 
-	for (i = 0; i < page_count; i++) {
+	for_each_sg(obj->pages->sgl, sg, page_count, i) {
+		struct page *page = sg_page(sg);
+
 		if (obj->dirty)
-			set_page_dirty(obj->pages[i]);
+			set_page_dirty(page);
 
 		if (obj->madv == I915_MADV_WILLNEED)
-			mark_page_accessed(obj->pages[i]);
+			mark_page_accessed(page);
 
-		page_cache_release(obj->pages[i]);
+		page_cache_release(page);
 	}
 	obj->dirty = 0;
 
-	drm_free_large(obj->pages);
-	obj->pages = NULL;
+	sg_free_table(obj->pages);
+	kfree(obj->pages);
 }
 
 static int
@@ -1682,6 +1701,7 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
 		return -EBUSY;
 
 	ops->put_pages(obj);
+	obj->pages = NULL;
 
 	list_del(&obj->gtt_list);
 	if (i915_gem_object_is_purgeable(obj))
@@ -1739,6 +1759,8 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
 	int page_count, i;
 	struct address_space *mapping;
+	struct sg_table *st;
+	struct scatterlist *sg;
 	struct page *page;
 	gfp_t gfp;
 
@@ -1749,20 +1771,27 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 	BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);
 	BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);
 
-	/* Get the list of pages out of our struct file.  They'll be pinned
-	 * at this point until we release them.
-	 */
+	st = kmalloc(sizeof(*st), GFP_KERNEL);
+	if (st == NULL)
+		return -ENOMEM;
+
 	page_count = obj->base.size / PAGE_SIZE;
-	obj->pages = drm_malloc_ab(page_count, sizeof(struct page *));
-	if (obj->pages == NULL)
+	if (sg_alloc_table(st, page_count, GFP_KERNEL)) {
+		sg_free_table(st);
+		kfree(st);
 		return -ENOMEM;
+	}
 
-	/* Fail silently without starting the shrinker */
+	/* Get the list of pages out of our struct file.  They'll be pinned
+	 * at this point until we release them.
+	 *
+	 * Fail silently without starting the shrinker
+	 */
 	mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
 	gfp = mapping_gfp_mask(mapping);
 	gfp |= __GFP_NORETRY | __GFP_NOWARN;
 	gfp &= ~(__GFP_IO | __GFP_WAIT);
-	for (i = 0; i < page_count; i++) {
+	for_each_sg(st->sgl, sg, page_count, i) {
 		page = shmem_read_mapping_page_gfp(mapping, i, gfp);
 		if (IS_ERR(page)) {
 			i915_gem_purge(dev_priv, page_count);
@@ -1785,20 +1814,20 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 			gfp &= ~(__GFP_IO | __GFP_WAIT);
 		}
 
-		obj->pages[i] = page;
+		sg_set_page(sg, page, PAGE_SIZE, 0);
 	}
 
 	if (i915_gem_object_needs_bit17_swizzle(obj))
 		i915_gem_object_do_bit_17_swizzle(obj);
 
+	obj->pages = st;
 	return 0;
 
 err_pages:
-	while (i--)
-		page_cache_release(obj->pages[i]);
-
-	drm_free_large(obj->pages);
-	obj->pages = NULL;
+	for_each_sg(st->sgl, sg, i, page_count)
+		page_cache_release(sg_page(sg));
+	sg_free_table(st);
+	kfree(st);
 	return PTR_ERR(page);
 }
 
@@ -2981,7 +3010,7 @@ i915_gem_clflush_object(struct drm_i915_gem_object *obj)
 
 	trace_i915_gem_object_clflush(obj);
 
-	drm_clflush_pages(obj->pages, obj->base.size / PAGE_SIZE);
+	drm_clflush_sg(obj->pages);
 }
 
 /** Flushes the GTT write domain for the object if it's dirty. */
@@ -3731,6 +3760,8 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 	i915_gem_object_put_pages(obj);
 	i915_gem_object_free_mmap_offset(obj);
 
+	BUG_ON(obj->pages);
+
 	drm_gem_object_release(&obj->base);
 	i915_gem_info_remove_obj(dev_priv, obj->base.size);
 
diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index eca4726f414..4bb1b94df5c 100644
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -28,33 +28,57 @@
 #include <linux/dma-buf.h>
 
 static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachment,
-				      enum dma_data_direction dir)
+					     enum dma_data_direction dir)
 {
 	struct drm_i915_gem_object *obj = attachment->dmabuf->priv;
-	struct drm_device *dev = obj->base.dev;
-	int npages = obj->base.size / PAGE_SIZE;
-	struct sg_table *sg;
-	int ret;
-	int nents;
+	struct sg_table *st;
+	struct scatterlist *src, *dst;
+	int ret, i;
 
-	ret = i915_mutex_lock_interruptible(dev);
+	ret = i915_mutex_lock_interruptible(obj->base.dev);
 	if (ret)
 		return ERR_PTR(ret);
 
 	ret = i915_gem_object_get_pages(obj);
 	if (ret) {
-		sg = ERR_PTR(ret);
+		st = ERR_PTR(ret);
+		goto out;
+	}
+
+	/* Copy sg so that we make an independent mapping */
+	st = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
+	if (st == NULL) {
+		st = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	ret = sg_alloc_table(st, obj->pages->nents, GFP_KERNEL);
+	if (ret) {
+		kfree(st);
+		st = ERR_PTR(ret);
+		goto out;
+	}
+
+	src = obj->pages->sgl;
+	dst = st->sgl;
+	for (i = 0; i < obj->pages->nents; i++) {
+		sg_set_page(dst, sg_page(src), PAGE_SIZE, 0);
+		dst = sg_next(dst);
+		src = sg_next(src);
+	}
+
+	if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) {
+		sg_free_table(st);
+		kfree(st);
+		st = ERR_PTR(-ENOMEM);
 		goto out;
 	}
 
-	/* link the pages into an SG then map the sg */
-	sg = drm_prime_pages_to_sg(obj->pages, npages);
-	nents = dma_map_sg(attachment->dev, sg->sgl, sg->nents, dir);
 	i915_gem_object_pin_pages(obj);
 
 out:
-	mutex_unlock(&dev->struct_mutex);
-	return sg;
+	mutex_unlock(&obj->base.dev->struct_mutex);
+	return st;
 }
 
 static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
@@ -80,7 +104,9 @@ static void *i915_gem_dmabuf_vmap(struct dma_buf *dma_buf)
 {
 	struct drm_i915_gem_object *obj = dma_buf->priv;
 	struct drm_device *dev = obj->base.dev;
-	int ret;
+	struct scatterlist *sg;
+	struct page **pages;
+	int ret, i;
 
 	ret = i915_mutex_lock_interruptible(dev);
 	if (ret)
@@ -92,22 +118,33 @@ static void *i915_gem_dmabuf_vmap(struct dma_buf *dma_buf)
 	}
 
 	ret = i915_gem_object_get_pages(obj);
-	if (ret) {
-		mutex_unlock(&dev->struct_mutex);
-		return ERR_PTR(ret);
-	}
+	if (ret)
+		goto error;
 
-	obj->dma_buf_vmapping = vmap(obj->pages, obj->base.size / PAGE_SIZE, 0, PAGE_KERNEL);
-	if (!obj->dma_buf_vmapping) {
-		DRM_ERROR("failed to vmap object\n");
-		goto out_unlock;
-	}
+	ret = -ENOMEM;
+
+	pages = drm_malloc_ab(obj->pages->nents, sizeof(struct page *));
+	if (pages == NULL)
+		goto error;
+
+	for_each_sg(obj->pages->sgl, sg, obj->pages->nents, i)
+		pages[i] = sg_page(sg);
+
+	obj->dma_buf_vmapping = vmap(pages, obj->pages->nents, 0, PAGE_KERNEL);
+	drm_free_large(pages);
+
+	if (!obj->dma_buf_vmapping)
+		goto error;
 
 	obj->vmapping_count = 1;
 	i915_gem_object_pin_pages(obj);
 out_unlock:
 	mutex_unlock(&dev->struct_mutex);
 	return obj->dma_buf_vmapping;
+
+error:
+	mutex_unlock(&dev->struct_mutex);
+	return ERR_PTR(ret);
 }
 
 static void i915_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
@@ -184,22 +221,19 @@ static const struct dma_buf_ops i915_dmabuf_ops =  {
 };
 
 struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
-				struct drm_gem_object *gem_obj, int flags)
+				      struct drm_gem_object *gem_obj, int flags)
 {
 	struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
 
-	return dma_buf_export(obj, &i915_dmabuf_ops,
-						  obj->base.size, 0600);
+	return dma_buf_export(obj, &i915_dmabuf_ops, obj->base.size, 0600);
 }
 
 struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
-				struct dma_buf *dma_buf)
+					     struct dma_buf *dma_buf)
 {
 	struct dma_buf_attachment *attach;
 	struct sg_table *sg;
 	struct drm_i915_gem_object *obj;
-	int npages;
-	int size;
 	int ret;
 
 	/* is this one of own objects? */
@@ -223,21 +257,19 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
 		goto fail_detach;
 	}
 
-	size = dma_buf->size;
-	npages = size / PAGE_SIZE;
-
 	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 	if (obj == NULL) {
 		ret = -ENOMEM;
 		goto fail_unmap;
 	}
 
-	ret = drm_gem_private_object_init(dev, &obj->base, size);
+	ret = drm_gem_private_object_init(dev, &obj->base, dma_buf->size);
 	if (ret) {
 		kfree(obj);
 		goto fail_unmap;
 	}
 
+	obj->has_dma_mapping = true;
 	obj->sg_table = sg;
 	obj->base.import_attach = attach;
 
@@ -249,3 +281,4 @@ fail_detach:
 	dma_buf_detach(dma_buf, attach);
 	return ERR_PTR(ret);
 }
+
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index e6b2205ecf6..4ab008397d6 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -210,7 +210,8 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
 		if (ret)
 			return ret;
 
-		vaddr = kmap_atomic(obj->pages[reloc->offset >> PAGE_SHIFT]);
+		vaddr = kmap_atomic(i915_gem_object_get_page(obj,
+							     reloc->offset >> PAGE_SHIFT));
 		*(uint32_t *)(vaddr + page_offset) = reloc->delta;
 		kunmap_atomic(vaddr);
 	} else {
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 18477314d85..e0c9bddb7d9 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -167,8 +167,7 @@ void i915_gem_cleanup_aliasing_ppgtt(struct drm_device *dev)
 }
 
 static void i915_ppgtt_insert_sg_entries(struct i915_hw_ppgtt *ppgtt,
-					 struct scatterlist *sg_list,
-					 unsigned sg_len,
+					 const struct sg_table *pages,
 					 unsigned first_entry,
 					 uint32_t pte_flags)
 {
@@ -180,12 +179,12 @@ static void i915_ppgtt_insert_sg_entries(struct i915_hw_ppgtt *ppgtt,
 	struct scatterlist *sg;
 
 	/* init sg walking */
-	sg = sg_list;
+	sg = pages->sgl;
 	i = 0;
 	segment_len = sg_dma_len(sg) >> PAGE_SHIFT;
 	m = 0;
 
-	while (i < sg_len) {
+	while (i < pages->nents) {
 		pt_vaddr = kmap_atomic(ppgtt->pt_pages[act_pd]);
 
 		for (j = first_pte; j < I915_PPGTT_PT_ENTRIES; j++) {
@@ -194,13 +193,11 @@ static void i915_ppgtt_insert_sg_entries(struct i915_hw_ppgtt *ppgtt,
 			pt_vaddr[j] = pte | pte_flags;
 
 			/* grab the next page */
-			m++;
-			if (m == segment_len) {
-				sg = sg_next(sg);
-				i++;
-				if (i == sg_len)
+			if (++m == segment_len) {
+				if (++i == pages->nents)
 					break;
 
+				sg = sg_next(sg);
 				segment_len = sg_dma_len(sg) >> PAGE_SHIFT;
 				m = 0;
 			}
@@ -213,44 +210,10 @@ static void i915_ppgtt_insert_sg_entries(struct i915_hw_ppgtt *ppgtt,
 	}
 }
 
-static void i915_ppgtt_insert_pages(struct i915_hw_ppgtt *ppgtt,
-				    unsigned first_entry, unsigned num_entries,
-				    struct page **pages, uint32_t pte_flags)
-{
-	uint32_t *pt_vaddr, pte;
-	unsigned act_pd = first_entry / I915_PPGTT_PT_ENTRIES;
-	unsigned first_pte = first_entry % I915_PPGTT_PT_ENTRIES;
-	unsigned last_pte, i;
-	dma_addr_t page_addr;
-
-	while (num_entries) {
-		last_pte = first_pte + num_entries;
-		last_pte = min_t(unsigned, last_pte, I915_PPGTT_PT_ENTRIES);
-
-		pt_vaddr = kmap_atomic(ppgtt->pt_pages[act_pd]);
-
-		for (i = first_pte; i < last_pte; i++) {
-			page_addr = page_to_phys(*pages);
-			pte = GEN6_PTE_ADDR_ENCODE(page_addr);
-			pt_vaddr[i] = pte | pte_flags;
-
-			pages++;
-		}
-
-		kunmap_atomic(pt_vaddr);
-
-		num_entries -= last_pte - first_pte;
-		first_pte = 0;
-		act_pd++;
-	}
-}
-
 void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
 			    struct drm_i915_gem_object *obj,
 			    enum i915_cache_level cache_level)
 {
-	struct drm_device *dev = obj->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
 	uint32_t pte_flags = GEN6_PTE_VALID;
 
 	switch (cache_level) {
@@ -261,7 +224,7 @@ void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
 		pte_flags |= GEN6_PTE_CACHE_LLC;
 		break;
 	case I915_CACHE_NONE:
-		if (IS_HASWELL(dev))
+		if (IS_HASWELL(obj->base.dev))
 			pte_flags |= HSW_PTE_UNCACHED;
 		else
 			pte_flags |= GEN6_PTE_UNCACHED;
@@ -270,26 +233,10 @@ void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
 		BUG();
 	}
 
-	if (obj->sg_table) {
-		i915_ppgtt_insert_sg_entries(ppgtt,
-					     obj->sg_table->sgl,
-					     obj->sg_table->nents,
-					     obj->gtt_space->start >> PAGE_SHIFT,
-					     pte_flags);
-	} else if (dev_priv->mm.gtt->needs_dmar) {
-		BUG_ON(!obj->sg_list);
-
-		i915_ppgtt_insert_sg_entries(ppgtt,
-					     obj->sg_list,
-					     obj->num_sg,
-					     obj->gtt_space->start >> PAGE_SHIFT,
-					     pte_flags);
-	} else
-		i915_ppgtt_insert_pages(ppgtt,
-					obj->gtt_space->start >> PAGE_SHIFT,
-					obj->base.size >> PAGE_SHIFT,
-					obj->pages,
-					pte_flags);
+	i915_ppgtt_insert_sg_entries(ppgtt,
+				     obj->sg_table ?: obj->pages,
+				     obj->gtt_space->start >> PAGE_SHIFT,
+				     pte_flags);
 }
 
 void i915_ppgtt_unbind_object(struct i915_hw_ppgtt *ppgtt,
@@ -361,44 +308,26 @@ void i915_gem_restore_gtt_mappings(struct drm_device *dev)
 
 int i915_gem_gtt_prepare_object(struct drm_i915_gem_object *obj)
 {
-	struct drm_device *dev = obj->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
-
-	/* don't map imported dma buf objects */
-	if (dev_priv->mm.gtt->needs_dmar && !obj->sg_table)
-		return intel_gtt_map_memory(obj->pages,
-					    obj->base.size >> PAGE_SHIFT,
-					    &obj->sg_list,
-					    &obj->num_sg);
-	else
+	if (obj->has_dma_mapping)
 		return 0;
+
+	if (!dma_map_sg(&obj->base.dev->pdev->dev,
+			obj->pages->sgl, obj->pages->nents,
+			PCI_DMA_BIDIRECTIONAL))
+		return -ENOSPC;
+
+	return 0;
 }
 
 void i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
 			      enum i915_cache_level cache_level)
 {
 	struct drm_device *dev = obj->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
 	unsigned int agp_type = cache_level_to_agp_type(dev, cache_level);
 
-	if (obj->sg_table) {
-		intel_gtt_insert_sg_entries(obj->sg_table->sgl,
-					    obj->sg_table->nents,
-					    obj->gtt_space->start >> PAGE_SHIFT,
-					    agp_type);
-	} else if (dev_priv->mm.gtt->needs_dmar) {
-		BUG_ON(!obj->sg_list);
-
-		intel_gtt_insert_sg_entries(obj->sg_list,
-					    obj->num_sg,
-					    obj->gtt_space->start >> PAGE_SHIFT,
-					    agp_type);
-	} else
-		intel_gtt_insert_pages(obj->gtt_space->start >> PAGE_SHIFT,
-				       obj->base.size >> PAGE_SHIFT,
-				       obj->pages,
-				       agp_type);
-
+	intel_gtt_insert_sg_entries(obj->sg_table ?: obj->pages,
+				    obj->gtt_space->start >> PAGE_SHIFT,
+				    agp_type);
 	obj->has_global_gtt_mapping = 1;
 }
 
@@ -418,10 +347,10 @@ void i915_gem_gtt_finish_object(struct drm_i915_gem_object *obj)
 
 	interruptible = do_idling(dev_priv);
 
-	if (obj->sg_list) {
-		intel_gtt_unmap_memory(obj->sg_list, obj->num_sg);
-		obj->sg_list = NULL;
-	}
+	if (!obj->has_dma_mapping)
+		dma_unmap_sg(&dev->pdev->dev,
+			     obj->pages->sgl, obj->pages->nents,
+			     PCI_DMA_BIDIRECTIONAL);
 
 	undo_idling(dev_priv, interruptible);
 }
diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index b964df51cec..8093ecd2ea3 100644
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -470,18 +470,20 @@ i915_gem_swizzle_page(struct page *page)
 void
 i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object *obj)
 {
+	struct scatterlist *sg;
 	int page_count = obj->base.size >> PAGE_SHIFT;
 	int i;
 
 	if (obj->bit_17 == NULL)
 		return;
 
-	for (i = 0; i < page_count; i++) {
-		char new_bit_17 = page_to_phys(obj->pages[i]) >> 17;
+	for_each_sg(obj->pages->sgl, sg, page_count, i) {
+		struct page *page = sg_page(sg);
+		char new_bit_17 = page_to_phys(page) >> 17;
 		if ((new_bit_17 & 0x1) !=
 		    (test_bit(i, obj->bit_17) != 0)) {
-			i915_gem_swizzle_page(obj->pages[i]);
-			set_page_dirty(obj->pages[i]);
+			i915_gem_swizzle_page(page);
+			set_page_dirty(page);
 		}
 	}
 }
@@ -489,6 +491,7 @@ i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object *obj)
 void
 i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj)
 {
+	struct scatterlist *sg;
 	int page_count = obj->base.size >> PAGE_SHIFT;
 	int i;
 
@@ -502,8 +505,9 @@ i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj)
 		}
 	}
 
-	for (i = 0; i < page_count; i++) {
-		if (page_to_phys(obj->pages[i]) & (1 << 17))
+	for_each_sg(obj->pages->sgl, sg, page_count, i) {
+		struct page *page = sg_page(sg);
+		if (page_to_phys(page) & (1 << 17))
 			__set_bit(i, obj->bit_17);
 		else
 			__clear_bit(i, obj->bit_17);
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index d6010135e40..dd49046bccd 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -888,20 +888,20 @@ i915_error_object_create(struct drm_i915_private *dev_priv,
 			 struct drm_i915_gem_object *src)
 {
 	struct drm_i915_error_object *dst;
-	int page, page_count;
+	int i, count;
 	u32 reloc_offset;
 
 	if (src == NULL || src->pages == NULL)
 		return NULL;
 
-	page_count = src->base.size / PAGE_SIZE;
+	count = src->base.size / PAGE_SIZE;
 
-	dst = kmalloc(sizeof(*dst) + page_count * sizeof(u32 *), GFP_ATOMIC);
+	dst = kmalloc(sizeof(*dst) + count * sizeof(u32 *), GFP_ATOMIC);
 	if (dst == NULL)
 		return NULL;
 
 	reloc_offset = src->gtt_offset;
-	for (page = 0; page < page_count; page++) {
+	for (i = 0; i < count; i++) {
 		unsigned long flags;
 		void *d;
 
@@ -924,30 +924,33 @@ i915_error_object_create(struct drm_i915_private *dev_priv,
 			memcpy_fromio(d, s, PAGE_SIZE);
 			io_mapping_unmap_atomic(s);
 		} else {
+			struct page *page;
 			void *s;
 
-			drm_clflush_pages(&src->pages[page], 1);
+			page = i915_gem_object_get_page(src, i);
+
+			drm_clflush_pages(&page, 1);
 
-			s = kmap_atomic(src->pages[page]);
+			s = kmap_atomic(page);
 			memcpy(d, s, PAGE_SIZE);
 			kunmap_atomic(s);
 
-			drm_clflush_pages(&src->pages[page], 1);
+			drm_clflush_pages(&page, 1);
 		}
 		local_irq_restore(flags);
 
-		dst->pages[page] = d;
+		dst->pages[i] = d;
 
 		reloc_offset += PAGE_SIZE;
 	}
-	dst->page_count = page_count;
+	dst->page_count = count;
 	dst->gtt_offset = src->gtt_offset;
 
 	return dst;
 
 unwind:
-	while (page--)
-		kfree(dst->pages[page]);
+	while (i--)
+		kfree(dst->pages[i]);
 	kfree(dst);
 	return NULL;
 }
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 55cdb4d30a1..984a0c5fbf5 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -464,7 +464,7 @@ init_pipe_control(struct intel_ring_buffer *ring)
 		goto err_unref;
 
 	pc->gtt_offset = obj->gtt_offset;
-	pc->cpu_page =  kmap(obj->pages[0]);
+	pc->cpu_page =  kmap(sg_page(obj->pages->sgl));
 	if (pc->cpu_page == NULL)
 		goto err_unpin;
 
@@ -491,7 +491,8 @@ cleanup_pipe_control(struct intel_ring_buffer *ring)
 		return;
 
 	obj = pc->obj;
-	kunmap(obj->pages[0]);
+
+	kunmap(sg_page(obj->pages->sgl));
 	i915_gem_object_unpin(obj);
 	drm_gem_object_unreference(&obj->base);
 
@@ -1026,7 +1027,7 @@ static void cleanup_status_page(struct intel_ring_buffer *ring)
 	if (obj == NULL)
 		return;
 
-	kunmap(obj->pages[0]);
+	kunmap(sg_page(obj->pages->sgl));
 	i915_gem_object_unpin(obj);
 	drm_gem_object_unreference(&obj->base);
 	ring->status_page.obj = NULL;
@@ -1053,7 +1054,7 @@ static int init_status_page(struct intel_ring_buffer *ring)
 	}
 
 	ring->status_page.gfx_addr = obj->gtt_offset;
-	ring->status_page.page_addr = kmap(obj->pages[0]);
+	ring->status_page.page_addr = kmap(sg_page(obj->pages->sgl));
 	if (ring->status_page.page_addr == NULL) {
 		ret = -ENOMEM;
 		goto err_unpin;