Re: [PATCH v5 10/19] vfio: Add infrastructure for bind_iommufd from userspace

Jason Gunthorpe
2023-02-28T12:52:58Z

On Tue, Feb 28, 2023 at 12:48:23PM +0000, Liu, Yi L wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Tuesday, February 28, 2023 8:30 PM
> >
> > On Tue, Feb 28, 2023 at 02:35:25AM +0000, Liu, Yi L wrote:
> >
> > > > And the commit message is sort of out of sync with the patch, more like:
> > > >
> > > > vfio: Pass the pt_id as an argument to vfio_iommufd_bind()
> > > >
> > > > To support binding the cdev the pt_id must come from userspace
> > instead
> > > > of being forced to the compat_ioas_id.
> > > >
> > >
> > > Got it. not only pt_id, also dev_id. 😊
> >
> > Maybe dev_id should be read back from the iommufd_device pointer in
> > the vfio_device. It is trivially stored in that memory already
>
> Yes. this somehow gives me a doubt. Why iommufd_device_bind() returns
> both iommufd_device pointer and the id back as id is already stored in the
> iommufd_device. Is it?

Yes, it was done this way to avoid another API to get the ID, but
perhaps that is more conveient for vfio anyhow. We could get rid of
the id return pointer as well

Jason