Re: [PATCH 1/2] mm: provide a sane PTE walking API for modules

[Paolo Bonzini]

On 09/02/21 09:14, Christoph Hellwig wrote:
> On Mon, Feb 08, 2021 at 07:18:56PM +0100, Paolo Bonzini wrote:
> > Fair enough.  I would expect that pretty much everyone using follow_pfn will
> > at least want to switch to this one (as it's less bad and not impossible to
> > use correctly), but I'll squash this in:
>
>
> Daniel looked into them, so he may correct me, but the other follow_pfn
> users and their destiny are:
>
>   - SGX, which is not modular and I think I just saw a patch to kill them
>   - v4l videobuf and frame vector: I think those are going away
>     entirely as they implement a rather broken pre-dmabuf P2P scheme
>   - vfio: should use MMU notifiers eventually

Yes, I'm thinking mostly of vfio, which could use follow_pte as a 
short-term fix for just the missing permission check.

There's also s390 PCI, which is also not modular.

Paolo

> Daniel, what happened to your follow_pfn series?