Re: [PATCH v9 3/4] iommu/arm-smmu-v3-iommufd: Report CFGI/TLBI-repeat erratum

[Jason Gunthorpe]

On Sun, Jul 26, 2026 at 08:19:03AM +0000, Ashish Mhetre wrote:
> A guest with access to VCMDQ generates its own invalidation commands
> and must apply any invalidation errata before submitting them. If the
> host also repeats those commands, each affected invalidation is issued
> four times instead of twice.
> 
> Add IOMMU_HW_INFO_ARM_SMMUV3_ERRATA_REPEAT_TLBI_CFGI to report the
> CFGI/TLBI-repeat erratum to user space. This allows the VMM to expose
> the erratum to the guest or apply the workaround itself.
> 
> Use the raw __arm_smmu_cmdq_issue_cmdlist() helper for user-provided
> invalidations so the host does not apply the workaround a second time.
> Add arm_smmu_erratum_repeat_tlbi_cfgi() to query the static key when
> populating the SMMUv3 hardware information.
> 
> Signed-off-by: Ashish Mhetre <amhetre@xxxxxxxxxx>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c |  7 +++++--
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c         |  7 ++++++-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h         |  1 +
>  include/uapi/linux/iommufd.h                        | 13 ++++++++++++-
>  4 files changed, 24 insertions(+), 4 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

Jason