Re: [PATCH v5 2/9] iommufd: Support a HWPT without an iommu driver for noiommu

[Samiullah Khawaja]

On Mon, May 11, 2026 at 11:41:07AM -0700, Jacob Pan wrote:
> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
>
> Create just a little part of a real iommu driver, enough to
> slot in under the dev_iommu_ops() and allow iommufd to call
> domain_alloc_paging_flags() and fail everything else.
>
> This allows explicitly creating a HWPT under an IOAS.
>
> A new Kconfig option IOMMUFD_NOIOMMU is introduced to differentiate
> from the VFIO group/container based noiommu mode.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Jacob Pan <jacob.pan@xxxxxxxxxxxxxxxxxxx>
> ---
> v5:
>   - Use the new IOMMUFD_NOIOMMU Kconfig instead of VFIO_NOIOMMU
>   - Use consistent wording referring to VFIO noiommu mode (Kevin)
>   - Copyright date fix (Kevin)
> v4:
>   - Make iommufd_noiommu_ops const
> v3:
>   - Add comment to explain the design difference over the
>     legacy noiommu VFIO code.
> ---
> drivers/iommu/iommufd/Kconfig           |  13 +++
> drivers/iommu/iommufd/Makefile          |   1 +
> drivers/iommu/iommufd/hw_pagetable.c    |  15 +++-
> drivers/iommu/iommufd/hwpt_noiommu.c    | 102 ++++++++++++++++++++++++
> drivers/iommu/iommufd/iommufd_private.h |   2 +
> 5 files changed, 131 insertions(+), 2 deletions(-)
> create mode 100644 drivers/iommu/iommufd/hwpt_noiommu.c

Reviewed-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>