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Diffstat (limited to 'drivers/xen/swiotlb-xen.c')
-rw-r--r--drivers/xen/swiotlb-xen.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 1eac0731c349..ebd8f218a788 100644
--- 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)