Re: [PATCH v3 2/3] intel_iommu: fix type of the mask field in VTDIOTLBPageInvInfo

[Michael S. Tsirkin]

On Fri, Jul 05, 2024 at 09:52:48AM +0000, CLEMENT MATHIEU--DRIF wrote:
> 
> 
> On 05/07/2024 10:51, Michael S. Tsirkin wrote:
> 
>     Caution: External email. Do not open attachments or click links, unless 
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> 
>     On Fri, Jul 05, 2024 at 05:03:17AM +0000, CLEMENT MATHIEU--DRIF wrote:
> 
>         From: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
> 
>         VTDIOTLBPageInvInfo.mask might not fit in an uint8_t.
> 
>     I think what you mean is that is assigned values that might not
>     fit .... it's u8 ATM so of course it fits.
> 
> What about :
> "The mask stored into VTDIOTLBPageInvInfo.mask might not fit in an uint8_t. 
> Use
> uint64_t to avoid overflows"

No, the mask stored there is u8.
You mean "that we are trying to store into ".

> 
> 
>         Moreover, this field is used in binary operations with 64-bit 
> addresses.
> 
>     So what?
> 
> I thing the first part of the message is enough, the issue comes from the fact
> that the mask does not fit into the type
> 
> 
> 
>         Signed-off-by: Clément Mathieu--Drif 
> <clement.mathieu--drif@eviden.com>
>         ---
>          hw/i386/intel_iommu_internal.h | 2 +-
>          1 file changed, 1 insertion(+), 1 deletion(-)
> 
>         diff --git a/hw/i386/intel_iommu_internal.h 
> b/hw/i386/intel_iommu_internal.h
>         index cbc4030031..5fcbe2744f 100644
>         --- a/hw/i386/intel_iommu_internal.h
>         +++ b/hw/i386/intel_iommu_internal.h
>         @@ -436,7 +436,7 @@ struct VTDIOTLBPageInvInfo {
>              uint16_t domain_id;
>              uint32_t pasid;
>              uint64_t addr;
>         -    uint8_t mask;
>         +    uint64_t mask;
>          };
>          typedef struct VTDIOTLBPageInvInfo VTDIOTLBPageInvInfo;
> 
>         --
>         2.45.2
> 
>