Re: [PATCH v8 13/15] iommufd/viommu: Allow vIOMMUs without a parent HWPT

[Nicolin Chen]

On Wed, Nov 04, 2026 at 09:46:30PM +0530, Aneesh Kumar K.V (Arm) wrote:
> VIOMMU_ALLOC currently requires a nesting parent HWPT_PAGING even when
> the selected vIOMMU implementation has no use for one. This would force
> implementations such as the following Arm Realm vIOMMU to create an
> unused parent.

IIRC, MSI on ARM still goes through the NS pathway. So, it wouldn't
be "unused" if the device attaches to it (or its nested hwpts)?

By dropping the nesting parent from VIOMMU, it just simplifies the
attachment to an S1 paging hwpt, right?

Nicolin