Re: [PATCH V2 01/11] iommufd: Support a HWPT without an iommu driver for noiommu

Jason Gunthorpe
2026-03-23T22:10:39Z

On Mon, Mar 23, 2026 at 02:11:32PM -0700, Jacob Pan wrote:

> +/*
> + * AMDV1 is used as a dummy page table for no-IOMMU mode, similar to the
> + * iommufd selftest mock page table.
> + * Unlike legacy VFIO no-IOMMU mode, where no container level APIs are
> + * supported, this allows IOAS and hwpt objects to exist without hardware
> + * IOMMU support. IOVAs are used only for IOVA-to-PA lookups not for
> + * hardware translation in DMA.
> + *
> + * This is only used with iommufd and cdev-based interfaces and does not
> + * apply to legacy VFIO group-container based noiommu mode.
> + */
> static const struct iommu_domain_ops noiommu_amdv1_ops = {

That seems clear

Jason