- bool local = PFN_DOWN(dev_addr) == page_to_pfn(page);
- /* Dom0 is mapped 1:1, so if pfn == mfn the page is local otherwise
- * is 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. */
+ 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);
+
+ /*
+ * 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.
+ */