Signed-off-by: Chris Wilson <ch...@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 a2fb2aa..a29c259 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

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