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

[Samiullah Khawaja <skhawaja@google.com>]

On Mon, May 11, 2026 at 11:41:07AM -0700, Jacob Pan wrote:
>From: Jason Gunthorpe <jgg@nvidia.com>
>
>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@nvidia.com>
>Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
>---
>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@google.com>