Merge branch 'akpm-current/current'

[karo-tx-linux.git] / arch / arm / xen / mm.c

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index 99eec9063f68afd075dfe87e5a2f0d0ef30502cf..c5f9a9e3d1f393daa161ce8349c820462870a942 100644 (file)
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -48,22 +48,22 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
        size_t size, enum dma_data_direction dir, enum dma_cache_op op)
 {
        struct gnttab_cache_flush cflush;
-       unsigned long pfn;
+       unsigned long xen_pfn;
        size_t left = size;
 
-       pfn = (handle >> PAGE_SHIFT) + offset / PAGE_SIZE;
-       offset %= PAGE_SIZE;
+       xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE;
+       offset %= XEN_PAGE_SIZE;
 
        do {
                size_t len = left;
        
                /* buffers in highmem or foreign pages cannot cross page
                 * boundaries */
-               if (len + offset > PAGE_SIZE)
-                       len = PAGE_SIZE - offset;
+               if (len + offset > XEN_PAGE_SIZE)
+                       len = XEN_PAGE_SIZE - offset;
 
                cflush.op = 0;
-               cflush.a.dev_bus_addr = pfn << PAGE_SHIFT;
+               cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT;
                cflush.offset = offset;
                cflush.length = len;
 
@@ -79,7 +79,7 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
                        HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
 
                offset = 0;
-               pfn++;
+               xen_pfn++;
                left -= len;
        } while (left);
 }
@@ -138,10 +138,29 @@ void __xen_dma_sync_single_for_device(struct device *hwdev,
 }
 
 bool xen_arch_need_swiotlb(struct device *dev,
-                          unsigned long pfn,
-                          unsigned long bfn)
+                          phys_addr_t phys,
+                          dma_addr_t dev_addr)
 {
-       return (!hypercall_cflush && (pfn != bfn) && !is_device_dma_coherent(dev));
+       unsigned int xen_pfn = XEN_PFN_DOWN(phys);
+       unsigned int bfn = XEN_PFN_DOWN(dev_addr);
+
+       /*
+        * The swiotlb buffer should be used if
+        *      - Xen doesn't have the cache flush hypercall
+        *      - The Linux page refers to foreign memory
+        *      - The device doesn't support coherent DMA request
+        *
+        * The Linux page may be spanned acrros multiple Xen page, although
+        * it's not possible to have a mix of local and foreign Xen page.
+        * Furthermore, range_straddles_page_boundary is already checking
+        * if buffer is physically contiguous in the host RAM.
+        *
+        * Therefore we only need to check the first Xen page to know if we
+        * require a bounce buffer because the device doesn't support coherent
+        * memory and we are not able to flush the cache.
+        */
+       return (!hypercall_cflush && (xen_pfn != bfn) &&
+               !is_device_dma_coherent(dev));
 }
 
 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,