Re: [PATCH v5 0/6] iommufd: Iterate the cache invalidation array in the core

[Will Deacon]

On Tue, 28 Jul 2026 10:33:32 -0700, Nicolin Chen wrote:
> The vIOMMU cache_invalidate() and the nested-HWPT cache_invalidate_user()
> ops are each handed the full user invalidation array and must report, via
> array->entry_num, how many of its entries they handled. That makes every
> driver open-code the same array walk, with real downsides:
> 
>  - each driver carries its own loop and sub-array bookkeeping;
>  - the ARM SMMUv3 driver allocates a buffer sized to the whole array just
>    to iterate over it;
>  - hand-rolling the loop left the ARM SMMUv3 driver with two long-standing
>    bugs:
>     1) on a conversion failure it counts commands that it converted but
>        never issued, so user space skips invalidations that never reached
>        the cmdq;
>     2) it rejects a zero-length array, which the uAPI documents as a valid
>        request that only probes the data type.
> 
> [...]

Applied first patch to iommu (arm/smmu/updates), thanks!

[1/6] iommu/arm-smmu-v3: Support IDR5.DS and widen the TLBI SCALE field
      https://git.kernel.org/iommu/c/773f2b9e3670

Cheers,
-- 
Will

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