Subject: Re: [PATCH kernel] powerpc/iommu: Add iommu_ops to report capabilities and allow blocking domains

From: Jason Gunthorpe <[email-masked]>
Date: Fri, 8 Jul 2022 08:55:22 -0300

On Fri, Jul 08, 2022 at 04:34:55PM +1000, Alexey Kardashevskiy wrote:

> For now I'll add a comment in spapr_tce_iommu_attach_dev() that it is fine
> to do nothing as tce_iommu_take_ownership() and
> tce_iommu_take_ownership_ddw() take care of not having active DMA mappings.

That will still cause a security problem because
tce_iommu_take_ownership()/etc are called too late. This is the moment
in the flow when the ownershift must change away from the DMA API that
power implements and to VFIO, not later.

Jason