@@ -35,14 +35,21 @@ static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
dma_addr_t dev_addr, unsigned long offset, size_t size,
enum dma_data_direction dir, struct dma_attrs *attrs)
{
- bool local = XEN_PFN_DOWN(dev_addr) == page_to_xen_pfn(page);
+ 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 be spanned accross
- * multiple Xen page, it's not possible to have a mix of local and
- * foreign Xen page. 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, 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.
*/
if (local)
__generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);