Re: How to express "externally managed" IOMMU domains for VFIO/IOMMUFD ?

[Jason Gunthorpe]

On Thu, Apr 23, 2026 at 08:01:50AM +0000, Tian, Kevin wrote:
> > On Xen, we have a dedicated hypercalls for moving a device into another
> > guest (so it no longer belongs in Dom0, at far as DMA is concerned).
> > 
> > But it looks like there are no way to describe that idea of "attach that
> > device to this VM" nor "the device is in a VM"; which makes that
> > impracticable.
> > 
> > There may be things that could be done with the vIOMMU objects, but
> > there would be no "parent domain" in such case, as said earlier it
> > doesn't exist in the IOMMU subsystem.
> > 
> > What is expected to be done instead ?
> > 
> > Teddy
> > 
> > [1] https://www.youtube.com/watch?v=pLMGRgEJ-Eg
> > 
> 
> It'd be much easier to collect comments if you can put plain words
> to explain the problem rather than expecting other folks to watch
> the video first...

It sounds like CC and pkvm to me so I think it should re-use those
mechanisms..

Jason