drm/radeon: add userptr flag to limit it to anonymous memory v2

Avoid problems with writeback by limiting userptr to anonymous memory.

v2: add commit and code comments

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 13 insertions, 1 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index 993ab223b503..032736b429bf 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -290,7 +290,8 @@ int radeon_gem_userptr_ioctl(struct drm_device *dev, void *data,
                 return -EACCES;
 
         /* reject unknown flag values */
-        if (args->flags & ~RADEON_GEM_USERPTR_READONLY)
+        if (args->flags & ~(RADEON_GEM_USERPTR_READONLY |
+            RADEON_GEM_USERPTR_ANONONLY))
                 return -EINVAL;
 
         /* readonly pages not tested on older hardware */
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index b20933fa35c6..12e37b1ddc40 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -538,6 +538,16 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
         if (current->mm != gtt->usermm)
                 return -EPERM;
 
+        if (gtt->userflags & RADEON_GEM_USERPTR_ANONONLY) {
+                /* check that we only pin down anonymous memory
+                   to prevent problems with writeback */
+                unsigned long end = gtt->userptr + ttm->num_pages * PAGE_SIZE;
+                struct vm_area_struct *vma;
+                vma = find_vma(gtt->usermm, gtt->userptr);
+                if (!vma || vma->vm_file || vma->vm_end < end)
+                        return -EPERM;
+        }
+
         do {
                 unsigned num_pages = ttm->num_pages - pinned;
                 uint64_t userptr = gtt->userptr + pinned * PAGE_SIZE;
diff --git a/include/uapi/drm/radeon_drm.h b/include/uapi/drm/radeon_drm.h
index 3a9f20930372..9720e1a36848 100644
--- a/include/uapi/drm/radeon_drm.h
+++ b/include/uapi/drm/radeon_drm.h
@@ -816,6 +816,7 @@ struct drm_radeon_gem_create {
  * perform any operation.
  */
 #define RADEON_GEM_USERPTR_READONLY     (1 << 0)
+#define RADEON_GEM_USERPTR_ANONONLY     (1 << 1)
 
 struct drm_radeon_gem_userptr {
         uint64_t                addr;