drm/i915: Align initial plane backing objects correctly

commit f37b5c2b upstream.

Some bios really like to joke and start the planes at an offset ...
hooray!

Align start and end to fix this.

v2: Fixup calculation of size, spotted by Chris Wilson.

v3: Fix serious fumble I've just spotted.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86883
Cc: Johannes W <jargon@molb.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reported-and-tested-by: Johannes W <jargon@molb.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
[Jani: split WARN_ONs, rebase on v4.0-rc1]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/i915/i915_gem_stolen.c

@@ -485,10 +485,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 			stolen_offset, gtt_offset, size);
 
 	/* KISS and expect everything to be page-aligned */
-	BUG_ON(stolen_offset & 4095);
-	BUG_ON(size & 4095);
-
-	if (WARN_ON(size == 0))
+	if (WARN_ON(size == 0 || stolen_offset & 4095 || size & 4095))
 		return NULL;
 
 	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);

drivers/gpu/drm/i915/intel_display.c

@@ -2339,13 +2339,19 @@ static bool intel_alloc_plane_obj(struct intel_crtc *crtc,
 	struct drm_device *dev = crtc->base.dev;
 	struct drm_i915_gem_object *obj = NULL;
 	struct drm_mode_fb_cmd2 mode_cmd = { 0 };
-	u32 base = plane_config->base;
+	u32 base_aligned = round_down(plane_config->base, PAGE_SIZE);
+	u32 size_aligned = round_up(plane_config->base + plane_config->size,
+				    PAGE_SIZE);
+
+	size_aligned -= base_aligned;
 
 	if (plane_config->size == 0)
 		return false;
 
-	obj = i915_gem_object_create_stolen_for_preallocated(dev, base, base,
-							     plane_config->size);
+	obj = i915_gem_object_create_stolen_for_preallocated(dev,
+							     base_aligned,
+							     base_aligned,
+							     size_aligned);
 	if (!obj)
 		return false;
 
@@ -6660,8 +6666,7 @@ static void i9xx_get_plane_config(struct intel_crtc *crtc,
 	aligned_height = intel_align_height(dev, crtc->base.primary->fb->height,
 					    plane_config->tiled);
 
-	plane_config->size = PAGE_ALIGN(crtc->base.primary->fb->pitches[0] *
-					aligned_height);
+	plane_config->size = crtc->base.primary->fb->pitches[0] * aligned_height;
 
 	DRM_DEBUG_KMS("pipe/plane %d/%d with fb: size=%dx%d@%d, offset=%x, pitch %d, size 0x%x\n",
 		      pipe, plane, crtc->base.primary->fb->width,
@@ -7711,8 +7716,7 @@ static void ironlake_get_plane_config(struct intel_crtc *crtc,
 	aligned_height = intel_align_height(dev, crtc->base.primary->fb->height,
 					    plane_config->tiled);
 
-	plane_config->size = PAGE_ALIGN(crtc->base.primary->fb->pitches[0] *
-					aligned_height);
+	plane_config->size = crtc->base.primary->fb->pitches[0] * aligned_height;
 
 	DRM_DEBUG_KMS("pipe/plane %d/%d with fb: size=%dx%d@%d, offset=%x, pitch %d, size 0x%x\n",
 		      pipe, plane, crtc->base.primary->fb->width,