+ /*
+ * In order to utilize 64K pages for an object with a size < 2M, we will
+ * need to support a 64K scratch page, given that every 16th entry for a
+ * page-table operating in 64K mode must point to a properly aligned 64K
+ * region, including any PTEs which happen to point to scratch.
+ *
+ * This is only relevant for the 48b PPGTT where we support
+ * huge-gtt-pages, see also i915_vma_insert().
+ *
+ * TODO: we should really consider write-protecting the scratch-page and
+ * sharing between ppgtt
+ */
+ if (i915_vm_is_48bit(vm) &&
+ HAS_PAGE_SIZES(vm->i915, I915_GTT_PAGE_SIZE_64K)) {
+ order = get_order(I915_GTT_PAGE_SIZE_64K);
+ page = alloc_pages(gfp | __GFP_ZERO, order);
+ if (page) {
+ addr = dma_map_page(vm->dma, page, 0,
+ I915_GTT_PAGE_SIZE_64K,
+ PCI_DMA_BIDIRECTIONAL);
+ if (unlikely(dma_mapping_error(vm->dma, addr))) {
+ __free_pages(page, order);
+ page = NULL;
+ }