1 files changed, 10 insertions, 24 deletions

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index cfbe46785a3b..ae1df496bf38 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -83,34 +83,18 @@ static inline dma_addr_t xen_virt_to_bus(void *address)
         return xen_phys_to_bus(virt_to_phys(address));
 }
 
-static int check_pages_physically_contiguous(unsigned long xen_pfn,
-                                             unsigned int offset,
-                                             size_t length)
+static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
 {
-        unsigned long next_bfn;
-        int i;
-        int nr_pages;
+        unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p);
+        unsigned int i, nr_pages = XEN_PFN_UP(xen_offset_in_page(p) + size);
 
         next_bfn = pfn_to_bfn(xen_pfn);
-        nr_pages = (offset + length + XEN_PAGE_SIZE-1) >> XEN_PAGE_SHIFT;
 
-        for (i = 1; i < nr_pages; i++) {
+        for (i = 1; i < nr_pages; i++)
                 if (pfn_to_bfn(++xen_pfn) != ++next_bfn)
-                        return 0;
-        }
-        return 1;
-}
+                        return 1;
 
-static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
-{
-        unsigned long xen_pfn = XEN_PFN_DOWN(p);
-        unsigned int offset = p & ~XEN_PAGE_MASK;
-
-        if (offset + size <= XEN_PAGE_SIZE)
-                return 0;
-        if (check_pages_physically_contiguous(xen_pfn, offset, size))
-                return 0;
-        return 1;
+        return 0;
 }
 
 static int is_xen_swiotlb_buffer(dma_addr_t dma_addr)
@@ -338,6 +322,7 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
                         xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs);
                         return NULL;
                 }
+                SetPageXenRemapped(virt_to_page(ret));
         }
         memset(ret, 0, size);
         return ret;
@@ -361,8 +346,9 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
         /* Convert the size to actually allocated. */
         size = 1UL << (order + XEN_PAGE_SHIFT);
 
-        if (((dev_addr + size - 1 <= dma_mask)) ||
-            range_straddles_page_boundary(phys, size))
+        if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
+                     range_straddles_page_boundary(phys, size)) &&
+            TestClearPageXenRemapped(virt_to_page(vaddr)))
                 xen_destroy_contiguous_region(phys, order);
 
         xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);