[PATCH 18/24] drm/i915: Handle stolen objects for pread

[Chris Wilson <chris@chris-wilson.co.uk>]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c |  175 ++++++++++++++++++++++++++-------------
 1 file changed, 116 insertions(+), 59 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index bcf0708..d1c1b60 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -324,24 +324,21 @@ __copy_from_user_swizzled(char *gpu_vaddr, int gpu_offset,
  * Flushes invalid cachelines before reading the target if
  * needs_clflush is set. */
 static int
-shmem_pread_fast(struct page *page, int shmem_page_offset, int page_length,
+shmem_pread_fast(char *vaddr, int shmem_page_offset, int page_length,
 		 char __user *user_data,
 		 bool page_do_bit17_swizzling, bool needs_clflush)
 {
-	char *vaddr;
 	int ret;
 
 	if (unlikely(page_do_bit17_swizzling))
 		return -EINVAL;
 
-	vaddr = kmap_atomic(page);
 	if (needs_clflush)
 		drm_clflush_virt_range(vaddr + shmem_page_offset,
 				       page_length);
 	ret = __copy_to_user_inatomic(user_data,
 				      vaddr + shmem_page_offset,
 				      page_length);
-	kunmap_atomic(vaddr);
 
 	return ret ? -EFAULT : 0;
 }
@@ -371,14 +368,12 @@ shmem_clflush_swizzled_range(char *addr, unsigned long length,
 /* Only difference to the fast-path function is that this can handle bit17
  * and uses non-atomic copy and kmap functions. */
 static int
-shmem_pread_slow(struct page *page, int shmem_page_offset, int page_length,
+shmem_pread_slow(char *vaddr, int shmem_page_offset, int page_length,
 		 char __user *user_data,
 		 bool page_do_bit17_swizzling, bool needs_clflush)
 {
-	char *vaddr;
 	int ret;
 
-	vaddr = kmap(page);
 	if (needs_clflush)
 		shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
 					     page_length,
@@ -392,7 +387,6 @@ shmem_pread_slow(struct page *page, int shmem_page_offset, int page_length,
 		ret = __copy_to_user(user_data,
 				     vaddr + shmem_page_offset,
 				     page_length);
-	kunmap(page);
 
 	return ret ? - EFAULT : 0;
 }
@@ -403,6 +397,7 @@ i915_gem_shmem_pread(struct drm_device *dev,
 		     struct drm_i915_gem_pread *args,
 		     struct drm_file *file)
 {
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	char __user *user_data;
 	ssize_t remain;
 	loff_t offset;
@@ -433,76 +428,138 @@ i915_gem_shmem_pread(struct drm_device *dev,
 		}
 	}
 
-	ret = i915_gem_object_get_pages(obj);
-	if (ret)
-		return ret;
+	offset = args->offset;
 
-	i915_gem_object_pin_pages(obj);
+	if (obj->stolen) {
+		char *vaddr;
 
-	offset = args->offset;
+		vaddr = (char *)dev_priv->mm.stolen_base;
+		vaddr += obj->stolen->start + offset;
 
-	for_each_sg(obj->pages->sgl, sg, obj->pages->nents, i) {
-		struct page *page;
+		shmem_page_offset = offset_in_page(offset);
+		while (remain > 0) {
+			/* Operation in this page
+			 *
+			 * shmem_page_offset = offset within page in shmem file
+			 * page_length = bytes to copy for this page
+			 */
+			page_length = remain;
+			if ((shmem_page_offset + page_length) > PAGE_SIZE)
+				page_length = PAGE_SIZE - shmem_page_offset;
 
-		if (i < offset >> PAGE_SHIFT)
-			continue;
+			page_do_bit17_swizzling = obj_do_bit17_swizzling &&
+				((uintptr_t)vaddr & (1 << 17)) != 0;
 
-		if (remain <= 0)
-			break;
+			ret = shmem_pread_fast(vaddr, shmem_page_offset, page_length,
+					       user_data, page_do_bit17_swizzling,
+					       needs_clflush);
+			if (ret == 0)
+				goto next_stolen;
 
-		/* Operation in this page
-		 *
-		 * shmem_page_offset = offset within page in shmem file
-		 * page_length = bytes to copy for this page
-		 */
-		shmem_page_offset = offset_in_page(offset);
-		page_length = remain;
-		if ((shmem_page_offset + page_length) > PAGE_SIZE)
-			page_length = PAGE_SIZE - shmem_page_offset;
+			hit_slowpath = 1;
+			mutex_unlock(&dev->struct_mutex);
 
-		page = sg_page(sg);
-		page_do_bit17_swizzling = obj_do_bit17_swizzling &&
-			(page_to_phys(page) & (1 << 17)) != 0;
+			if (!prefaulted) {
+				ret = fault_in_multipages_writeable(user_data, remain);
+				/* Userspace is tricking us, but we've already clobbered
+				 * its pages with the prefault and promised to write the
+				 * data up to the first fault. Hence ignore any errors
+				 * and just continue. */
+				(void)ret;
+				prefaulted = 1;
+			}
 
-		ret = shmem_pread_fast(page, shmem_page_offset, page_length,
-				       user_data, page_do_bit17_swizzling,
-				       needs_clflush);
-		if (ret == 0)
-			goto next_page;
+			ret = shmem_pread_slow(vaddr, shmem_page_offset, page_length,
+					       user_data, page_do_bit17_swizzling,
+					       needs_clflush);
 
-		hit_slowpath = 1;
-		mutex_unlock(&dev->struct_mutex);
+			mutex_lock(&dev->struct_mutex);
+			if (ret)
+				goto out;
 
-		if (!prefaulted) {
-			ret = fault_in_multipages_writeable(user_data, remain);
-			/* Userspace is tricking us, but we've already clobbered
-			 * its pages with the prefault and promised to write the
-			 * data up to the first fault. Hence ignore any errors
-			 * and just continue. */
-			(void)ret;
-			prefaulted = 1;
+next_stolen:
+			remain -= page_length;
+			user_data += page_length;
+			vaddr += page_length;
+			shmem_page_offset = 0;
 		}
+	} else {
+		ret = i915_gem_object_get_pages(obj);
+		if (ret)
+			return ret;
 
-		ret = shmem_pread_slow(page, shmem_page_offset, page_length,
-				       user_data, page_do_bit17_swizzling,
-				       needs_clflush);
+		i915_gem_object_pin_pages(obj);
 
-		mutex_lock(&dev->struct_mutex);
+		for_each_sg(obj->pages->sgl, sg, obj->pages->nents, i) {
+			char *vaddr;
+			struct page *page;
 
-next_page:
-		mark_page_accessed(page);
+			if (i < offset >> PAGE_SHIFT)
+				continue;
 
-		if (ret)
-			goto out;
+			if (remain <= 0)
+				break;
 
-		remain -= page_length;
-		user_data += page_length;
-		offset += page_length;
+			/* Operation in this page
+			 *
+			 * shmem_page_offset = offset within page in shmem file
+			 * page_length = bytes to copy for this page
+			 */
+			shmem_page_offset = offset_in_page(offset);
+			page_length = remain;
+			if ((shmem_page_offset + page_length) > PAGE_SIZE)
+				page_length = PAGE_SIZE - shmem_page_offset;
+
+			page = sg_page(sg);
+			mark_page_accessed(page);
+
+			page_do_bit17_swizzling = obj_do_bit17_swizzling &&
+				(page_to_phys(page) & (1 << 17)) != 0;
+
+			vaddr = kmap_atomic(page);
+			ret = shmem_pread_fast(vaddr, shmem_page_offset, page_length,
+					       user_data, page_do_bit17_swizzling,
+					       needs_clflush);
+			kunmap_atomic(vaddr);
+
+			if (ret == 0)
+				goto next_page;
+
+			hit_slowpath = 1;
+			mutex_unlock(&dev->struct_mutex);
+
+			if (!prefaulted) {
+				ret = fault_in_multipages_writeable(user_data, remain);
+				/* Userspace is tricking us, but we've already clobbered
+				 * its pages with the prefault and promised to write the
+				 * data up to the first fault. Hence ignore any errors
+				 * and just continue. */
+				(void)ret;
+				prefaulted = 1;
+			}
+
+			vaddr = kmap(page);
+			ret = shmem_pread_slow(vaddr, shmem_page_offset, page_length,
+					       user_data, page_do_bit17_swizzling,
+					       needs_clflush);
+			kunmap(page);
+
+			mutex_lock(&dev->struct_mutex);
+
+			if (ret)
+				goto out_unpin;
+
+next_page:
+			remain -= page_length;
+			user_data += page_length;
+			offset += page_length;
+		}
+out_unpin:
+		i915_gem_object_unpin_pages(obj);
 	}
 
-out:
-	i915_gem_object_unpin_pages(obj);
 
+out:
 	if (hit_slowpath) {
 		/* Fixup: Kill any reinstated backing storage pages */
 		if (obj->madv == __I915_MADV_PURGED)
-- 
1.7.10.4