> -----Original Message-----
> From: Zhenzhong Duan <[email protected]>
> Sent: 27 May 2026 06:47
> To: [email protected]
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; Jason Gunthorpe
> <[email protected]>; Nicolin Chen <[email protected]>; Shameer Kolothum
> Thodi <[email protected]>; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; Zhenzhong Duan <[email protected]>
> Subject: [PATCH v6 03/17] vfio/iommufd: Create nesting parent hwpt with
> IOMMU_HWPT_ALLOC_PASID flag
>
> External email: Use caution opening links or attachments
>
>
> When both device and vIOMMU have PASID enabled, then guest may setup
> pasid usages such as SVM.
>
> VFIO needs to be aware of potential pasid usage and should attach the
> non-pasid part of pasid-capable device to hwpt flagged with
> IOMMU_HWPT_ALLOC_PASID.
>
> ARM SMMU doesn't support IOMMU_HWPT_ALLOC_PASID, only VTD need it.
> So
> we can't check the existing vIOMMU flag VIOMMU_FLAG_PASID_SUPPORTED
> to
> determine if set flag IOMMU_HWPT_ALLOC_PASID. Instead, introduce a new
> flag VIOMMU_FLAG_WANT_PASID_ATTACH which will only be exposed by
> VTD.
>
> Opportunistically add documentation for VIOMMU_FLAG_PASID_SUPPORTED
> and explain the difference with VIOMMU_FLAG_WANT_PASID_ATTACH.
>
> Signed-off-by: Zhenzhong Duan <[email protected]>
> Reviewed-by: Yi Liu <[email protected]>
> Tested-by: Xudong Hao <[email protected]>
Reviewed-by: Shameer Kolothum <[email protected]>
Thanks,
Shameer
