drm/i915: Allow i915_gem_setup_global_gtt to fail

We already needs this just as a safety check in case the preallocation
reservation dance fails. But we definitely need this to be able to
move tha aliasing ppgtt setup back out of the context code to this
place, where it belongs.
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -4754,7 +4754,12 @@ int i915_gem_init(struct drm_device *dev)
 		dev_priv->gt.stop_ring = intel_logical_ring_stop;
 	}
 
-	i915_gem_init_userptr(dev);
+	ret = i915_gem_init_userptr(dev);
+	if (ret) {
+		mutex_unlock(&dev->struct_mutex);
+		return ret;
+	}
+
 	i915_gem_init_global_gtt(dev);
 
 	ret = i915_gem_context_init(dev);

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -1698,7 +1698,7 @@ static void i915_gtt_color_adjust(struct drm_mm_node *node,
 	}
 }
 
-void i915_gem_setup_global_gtt(struct drm_device *dev,
+int i915_gem_setup_global_gtt(struct drm_device *dev,
 			      unsigned long start,
 			      unsigned long mappable_end,
 			      unsigned long end)
@@ -1734,8 +1734,10 @@ void i915_gem_setup_global_gtt(struct drm_device *dev,
 
 		WARN_ON(i915_gem_obj_ggtt_bound(obj));
 		ret = drm_mm_reserve_node(&ggtt_vm->mm, &vma->node);
-		if (ret)
-			DRM_DEBUG_KMS("Reservation failed\n");
+		if (ret) {
+			DRM_DEBUG_KMS("Reservation failed: %i\n", ret);
+			return ret;
+		}
 		obj->has_global_gtt_mapping = 1;
 	}
 
@@ -1752,6 +1754,8 @@ void i915_gem_setup_global_gtt(struct drm_device *dev,
 
 	/* And finally clear the reserved guard page */
 	ggtt_vm->clear_range(ggtt_vm, end - PAGE_SIZE, PAGE_SIZE, true);
+
+	return 0;
 }
 
 void i915_gem_init_global_gtt(struct drm_device *dev)

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -271,7 +271,7 @@ struct i915_hw_ppgtt {
 
 int i915_gem_gtt_init(struct drm_device *dev);
 void i915_gem_init_global_gtt(struct drm_device *dev);
-void i915_gem_setup_global_gtt(struct drm_device *dev, unsigned long start,
+int i915_gem_setup_global_gtt(struct drm_device *dev, unsigned long start,
 			      unsigned long mappable_end, unsigned long end);