Re: [PATCH v4 15/32] vfio: introduce KVM-owned IOMMU type

[Matthew Rosato]

On 3/15/22 10:38 AM, Jason Gunthorpe wrote:
> On Tue, Mar 15, 2022 at 09:49:01AM -0400, Matthew Rosato wrote:
>
> > The rationale for splitting steps 1 and 2 are that VFIO_SET_IOMMU doesn't
> > have a mechanism for specifying more than the type as an arg, no?  Otherwise
> > yes, you could specify a kvm fd at this point and it would have some other
> > advantages (e.g. skip notifier).  But we still can't use the IOMMU for
> > mapping until step 3.
>
> Stuff like this is why I'd be much happier if this could join our
> iommfd project so we can have clean modeling of the multiple iommu_domains.

I'd certainly be willing to collaborate so feel free to loop me in on 
the discussions; but I got the impression that iommufd is not close to 
ready (maybe I'm wrong?) -- if so I really don't want to completely 
delay this zPCI support behind it as it has a significant benefit for 
kvm guests on s390x :(