These changes are the raw update to linux-4.4.6-rt14. Kernel sources

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

diff --git a/kernel/arch/arm/include/asm/xen/page-coherent.h b/kernel/arch/arm/include/asm/xen/page-coherent.h
index efd5624..9408a99 100644 (file)
--- a/kernel/arch/arm/include/asm/xen/page-coherent.h
+++ b/kernel/arch/arm/include/asm/xen/page-coherent.h
@@ -35,11 +35,22 @@ 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 = 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.
+        */
        if (local)
                __generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);
        else
@@ -51,10 +62,14 @@ static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
                struct dma_attrs *attrs)
 {
        unsigned long pfn = PFN_DOWN(handle);
-       /* 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. */
+       /*
+        * 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)) {
                if (__generic_dma_ops(hwdev)->unmap_page)
                        __generic_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);