drm/i915: Allow objects to be created with no backing pages, but stolen space

In order to accommodate objects that are not backed by struct pages, but
instead point into a contiguous region of stolen space, we need to make
various changes to avoid dereferencing obj->pages or obj->base.filp.

First introduce a marker for the stolen object, that specifies its
offset into the stolen region and implies that it has no backing pages.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 62619e3..58e6676 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -124,6 +124,8 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
        if (obj->gtt_space != NULL)
                seq_printf(m, " (gtt offset: %08x, size: %08x)",
                           obj->gtt_offset, (unsigned int)obj->gtt_space->size);
+       if (obj->stolen)
+               seq_printf(m, " (stolen: %08lx)", obj->stolen->start);
        if (obj->pin_mappable || obj->fault_mappable) {
                char s[3], *t = s;
                if (obj->pin_mappable)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6969c72..1646d03 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -962,6 +962,8 @@ struct drm_i915_gem_object {
 
        /** Current space allocated to this object in the GTT, if any. */
        struct drm_mm_node *gtt_space;
+       /** Stolen memory for this object, instead of being backed by shmem. */
+       struct drm_mm_node *stolen;
        struct list_head gtt_list;
 
        /** This object's place on the active/inactive lists */