The iommu_table_ops::exchange() callback writes new TCE to the table
and returns old value and permission mask. The old TCE value is
correctly converted from BE to CPU endian; however permission mask
was calculated from BE value and therefore always returned DMA_NONE
which could cause memory leak on LE systems using VFIO SPAPR TCE IOMMU v1
driver.

This fixes pnv_tce_xchg() to have @oldtce a CPU endian.

Fixes: 05c6cfb9dce0d13d37e9d007ee6a4af36f1c0a58
Cc: sta...@vger.kernel.org # 4.2+
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
 arch/powerpc/platforms/powernv/pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci.c 
b/arch/powerpc/platforms/powernv/pci.c
index 1d92bd9..7b17f88 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -620,8 +620,8 @@ int pnv_tce_xchg(struct iommu_table *tbl, long index,
        if (newtce & TCE_PCI_WRITE)
                newtce |= TCE_PCI_READ;
 
-       oldtce = xchg(pnv_tce(tbl, idx), cpu_to_be64(newtce));
-       *hpa = be64_to_cpu(oldtce) & ~(TCE_PCI_READ | TCE_PCI_WRITE);
+       oldtce = be64_to_cpu(xchg(pnv_tce(tbl, idx), cpu_to_be64(newtce)));
+       *hpa = oldtce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
        *direction = iommu_tce_direction(oldtce);
 
        return 0;
-- 
2.5.0.rc3

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