[PATCH] Fixed an off-by-one error in the AMD IOMMU driver.

[PATCH] Fixed an off-by-one error in the AMD IOMMU driver.

[Neil Turton]

The variable amd_iommu_last_bdf holds the maximum bdf of any device
controlled by an IOMMU, so the number of device entries needed is
amd_iommu_last_bdf+1.  The function tbl_size used amd_iommu_last_bdf
instead.  This would be a problem if the last device were a large
enough power of 2.

Signed-off-by: Neil Turton <nturton@solarflare.com>
---
 arch/x86/kernel/amd_iommu_init.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 42c33ce..61479ba 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -175,7 +175,7 @@ static inline void update_last_devid(u16 devid)
 static inline unsigned long tbl_size(int entry_size)
 {
 	unsigned shift = PAGE_SHIFT +
-			 get_order(amd_iommu_last_bdf * entry_size);
+			 get_order(((int)amd_iommu_last_bdf+1) * entry_size);

 	return 1UL << shift;
 }
-- 
1.5.5

Re: [PATCH] Fixed an off-by-one error in the AMD IOMMU driver.

[Roedel, Joerg]

On Thu, May 14, 2009 at 02:00:35PM +0100, Neil Turton wrote:
> The variable amd_iommu_last_bdf holds the maximum bdf of any device
> controlled by an IOMMU, so the number of device entries needed is
> amd_iommu_last_bdf+1.  The function tbl_size used amd_iommu_last_bdf
> instead.  This would be a problem if the last device were a large
> enough power of 2.
> 
> Signed-off-by: Neil Turton <nturton@solarflare.com>
> ---
>  arch/x86/kernel/amd_iommu_init.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
> index 42c33ce..61479ba 100644
> --- a/arch/x86/kernel/amd_iommu_init.c
> +++ b/arch/x86/kernel/amd_iommu_init.c
> @@ -175,7 +175,7 @@ static inline void update_last_devid(u16 devid)
>  static inline unsigned long tbl_size(int entry_size)
>  {
>  	unsigned shift = PAGE_SHIFT +
> -			 get_order(amd_iommu_last_bdf * entry_size);
> +			 get_order(((int)amd_iommu_last_bdf+1) * entry_size);
> 
>  	return 1UL << shift;
>  }

Applied, thanks Neil.

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