Re: [PATCH v9 0/4] iommu/arm-smmu-v3: Tegra264 invalidation workaround

[Ashish Mhetre <amhetre@nvidia.com>]

On 7/28/2026 4:45 PM, Will Deacon wrote:
> External email: Use caution opening links or attachments
>
>
> On Sun, 26 Jul 2026 08:19:00 +0000, Ashish Mhetre wrote:
>> Nvidia Tegra264 SMMUs are affected by an erratum where a TLB entry can
>> survive an invalidation that races with concurrent traffic targeting
>> the same entry. The hardware-recommended software workaround is to
>> issue every CFGI/TLBI command (each followed by CMD_SYNC) twice.
>> The second issue must execute only after the first issue's CMD_SYNC
>> has completed, giving the sequence:
>>
>> [...]
> Applied to iommu (arm/smmu/updates), thanks!
> But please check the comments from Sashiko if you get a chance:
>
> https://sashiko.dev/#/patchset/20260726081904.1408859-1-amhetre@nvidia.com

Both comments from Sashiko can be ignored.
Regarding comment on 2/4, it's false positive as at that point batches
won't have mix commands.
Regarding comment on 3/4, the erratum is exposed via hw_info. So, it
need to apply the WAR by checking the new flag else it's a bug in VMM.

> [1/4] iommu/arm-smmu-v3: Factor out CMDQ batch force-sync conditions
>        https://git.kernel.org/iommu/c/097bf4a02f2d
> [2/4] iommu/arm-smmu-v3: Add CFGI/TLBI-repeat workaround
>        https://git.kernel.org/iommu/c/95ed2da20283
> [3/4] iommu/arm-smmu-v3-iommufd: Report CFGI/TLBI-repeat erratum
>        https://git.kernel.org/iommu/c/d501d66815ee
> [4/4] iommu/arm-smmu-v3: Enable CFGI/TLBI-repeat workaround on Tegra264
>        https://git.kernel.org/iommu/c/06b15ddcfbc0
>
> Cheers,
> --
> Will
>
> https://fixes.arm64.dev
> https://next.arm64.dev
> https://will.arm64.dev