Re: [PATCH v9 1/6] iommufd: Support a HWPT without an iommu driver for noiommu

[Jason Gunthorpe]

On Tue, Jun 16, 2026 at 08:18:06PM +0000, Pranjal Shrivastava wrote:
> > diff --git a/drivers/iommu/iommufd/Kconfig b/drivers/iommu/iommufd/Kconfig
> > index 455bac0351f2..6c3bea83631b 100644
> > --- a/drivers/iommu/iommufd/Kconfig
> > +++ b/drivers/iommu/iommufd/Kconfig
> > @@ -16,6 +16,18 @@ config IOMMUFD
> >  	  If you don't know what to do here, say N.
> >  
> >  if IOMMUFD
> > +config IOMMUFD_NOIOMMU
> > +	bool
> > +	depends on !GENERIC_ATOMIC64 # IOMMU_PT_AMDV1 requires cmpxchg64
> 
> Nit: Should we explicitly depend on 64BIT here?
> I see further in the patch we assume 64-bit addresses:
> 
> +	cfg.common.hw_max_vasz_lg2 = 64;
> +	cfg.common.hw_max_oasz_lg2 = 52;

That will work fine on 32 bit, it is how all the drivers are being setup.

Jason