Re: [PATCH v5 3/4] intel_iommu: fix type of the mask field in VTDIOTLBPageInvInfo

[Yi Liu]

On 2024/7/8 19:39, CLEMENT MATHIEU--DRIF wrote:
> From: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
>
> The mask we are trying to store into VTDIOTLBPageInvInfo.mask might not
> fit in an uint8_t. Use uint64_t to avoid overflows.
>
> Per the below code, it can overflow as am can be larger than 8 according
> to the CH 6.5.2.3 IOTLB Invalidate. And you may want a fix tag as well.

aha, I meant you need to add a fix tag as this is a bug. :)

> info.mask = ~((1 << am) - 1);
>
> CH 6.5.2.3 IOTLB Invalidate
>
> Address Mask (AM): For page-selective-within-domain invalidations,
> the Address Mask specifies the number of low order bits of the ADDR
> field that must be masked for the invalidation operation. This field
> enables software to request invalidation of contiguous mappings for
> size-aligned regions. Refer to Table 19 for encodings of this field.
> When invalidating a large-page translation, software must use the
> appropriate Address Mask value (0 for 4KByte page, 9 for 2-MByte page,
> and 18 for 1-GByte page). Hardware implementations report the maximum
> supported address mask value through the Capability register.
>
> 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 faea23e8d6..5f32c36943 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;
>   

--
Regards,
Yi Liu