Re: [PATCH kernel] powerpc/powernv/ioda: Fix endianness when reading TCEs

[David Gibson]

On Wed, Jul 20, 2016 at 02:26:51PM +1000, Alexey Kardashevskiy wrote:
> 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 

Reviewed-by: David Gibson 

> ---
>  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;

-- 
David Gibson| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson


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[PATCH kernel] powerpc/powernv/ioda: Fix endianness when reading TCEs

[Alexey Kardashevskiy]

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 
---
 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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