RE: [RFC v2] /dev/iommu uAPI proposal

Tian, Kevin
2021-07-13T23:24:50Z

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Wednesday, July 14, 2021 7:23 AM
>
> On Tue, Jul 13, 2021 at 11:20:12PM +0000, Tian, Kevin wrote:
> > > From: Jason Gunthorpe <jgg@nvidia.com>
> > > Sent: Wednesday, July 14, 2021 7:03 AM
> > >
> > > On Tue, Jul 13, 2021 at 10:48:38PM +0000, Tian, Kevin wrote:
> > >
> > > > We can still bind to the parent with cookie, but with
> > > > iommu_register_ sw_device() IOMMU fd knows that this binding
> doesn't
> > > > need to establish any security context via IOMMU API.
> > >
> > > AFAIK there is no reason to involve the parent PCI or other device in
> > > SW mode. The iommufd doesn't need to be aware of anything there.
> > >
> >
> > Yes. but does it makes sense to have an unified model in IOMMU fd
> > which always have a [struct device, cookie] with flags to indicate whether
> > the binding/attaching should be specially handled for sw mdev? Or
> > are you suggesting that lacking of struct device is actually the indicator
> > for such trick?
>
> I think you've veered into such micro implementation details that it
> is better to wait and see how things look.
>
> The important point here is that whatever physical device is under a
> SW mdev does not need to be passed to the iommufd because there is
> nothing it can do with that information.
>

Make sense