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

[~andy/linux] / drivers / xen / swiotlb-xen.c

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 1eac0731c349f2067b42dea6e01f292453096d4b..ebd8f218a788b619f65438223cc85306e381caa7 100644 (file)
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -75,14 +75,32 @@ static unsigned long xen_io_tlb_nslabs;
 
 static u64 start_dma_addr;
 
+/*
+ * Both of these functions should avoid PFN_PHYS because phys_addr_t
+ * can be 32bit when dma_addr_t is 64bit leading to a loss in
+ * information if the shift is done before casting to 64bit.
+ */
 static inline dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
 {
-       return phys_to_machine(XPADDR(paddr)).maddr;
+       unsigned long mfn = pfn_to_mfn(PFN_DOWN(paddr));
+       dma_addr_t dma = (dma_addr_t)mfn << PAGE_SHIFT;
+
+       dma |= paddr & ~PAGE_MASK;
+
+       return dma;
 }
 
 static inline phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
 {
-       return machine_to_phys(XMADDR(baddr)).paddr;
+       unsigned long pfn = mfn_to_pfn(PFN_DOWN(baddr));
+       dma_addr_t dma = (dma_addr_t)pfn << PAGE_SHIFT;
+       phys_addr_t paddr = dma;
+
+       BUG_ON(paddr != dma); /* truncation has occurred, should never happen */
+
+       paddr |= baddr & ~PAGE_MASK;
+
+       return paddr;
 }
 
 static inline dma_addr_t xen_virt_to_bus(void *address)