Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

[mirror_ubuntu-zesty-kernel.git] / arch / arm / include / asm / xen / page-coherent.h

diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h
index 0375c8caa06194591e065f94bbb3d57a0565c847..9408a994cc91792bcf89a57d67982e21c677d9d7 100644 (file)
--- a/arch/arm/include/asm/xen/page-coherent.h
+++ b/arch/arm/include/asm/xen/page-coherent.h
@@ -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);