Re: [RFC 14/20] iommu/iommufd: Add iommufd_device_[de]attach_ioasid()

[Jason Gunthorpe]

On Wed, Sep 22, 2021 at 03:53:52AM +0000, Tian, Kevin wrote:

> Actually this was one open we closed in previous design proposal, but
> looks you have a different thought now.
> 
> vfio maintains one ioas per container. Devices in the container
> can be attached to different domains (e.g. due to snoop format). Every
> time when the ioas is updated, every attached domain is updated
> in accordance. 
> 
> You recommended one-ioas-one-domain model instead, i.e. any device 
> with a format incompatible with the one currently used in ioas has to 
> be attached to a new ioas, even if the two ioas's have the same mapping.
> This leads to compatibility check at attaching time.
> 
> Now you want returning back to the vfio model?

Oh, I thought we circled back again.. If we are all OK with one ioas
one domain then great.

> > If think sis taking in the iommfd_device then there isn't a logical
> > place to signal the PCIness
> 
> can you elaborate?

I mean just drop it and document it.

Jason