swiotlb-xen: use the same foreign page check everywhere

	     dma_addr_t dev_addr, unsigned long offset, size_t size,

	     enum dma_data_direction dir, unsigned long attrs)

{

	unsigned long page_pfn = page_to_xen_pfn(page);

	unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);

	unsigned long compound_pages =

		(1<<compound_order(page)) * XEN_PFN_PER_PAGE;

	bool local = (page_pfn <= dev_pfn) &&

		(dev_pfn - page_pfn < compound_pages);

	unsigned long pfn = PFN_DOWN(dev_addr);

	/*

	 * Dom0 is mapped 1:1, while the Linux page can span across

	 * multiple Xen pages, it's not possible for it to contain a

	 * mix of local and foreign Xen pages. So if the first xen_pfn

	 * == mfn the page is local otherwise it's a foreign page

	 * grant-mapped in dom0. If the page is local we can safely

	 * call the native dma_ops function, otherwise we call the xen

	 * specific function.

	 * Dom0 is mapped 1:1, and while the Linux page can span across multiple

	 * Xen pages, it is not possible for it to contain a mix of local and

	 * foreign Xen pages.  Calling pfn_valid on a foreign mfn will always

	 * return false, so if pfn_valid returns true the pages is local and we

	 * can use the native dma-direct functions, otherwise we call the Xen

	 * specific version.

	 */

	if (local)

	if (pfn_valid(pfn))

		dma_direct_map_page(hwdev, page, offset, size, dir, attrs);

	else

		__xen_dma_map_page(hwdev, page, dev_addr, offset, size, dir, attrs);

		size_t size, enum dma_data_direction dir, unsigned long attrs)

{

	unsigned long pfn = PFN_DOWN(handle);

	/*

	 * Dom0 is mapped 1:1, while the Linux page can be spanned accross

	 * multiple Xen page, it's not possible to have a mix of local and

	 * foreign Xen page. Dom0 is mapped 1:1, so calling pfn_valid on a

	 * foreign mfn will always return false. If the page is local we can

	 * safely call the native dma_ops function, otherwise we call the xen

	 * specific function.

	 */

	if (pfn_valid(pfn))

		dma_direct_unmap_page(hwdev, handle, size, dir, attrs);

	else