Re: [PATCH v5 15/19] iommufd: vfio container FD ioctl compatibility

Jason Wang
2022-11-23T04:31:31Z

On Wed, Nov 23, 2022 at 9:33 AM Tian, Kevin <kevin.tian@intel.com> wrote:
>
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Friday, November 18, 2022 11:22 PM
> >
> > On Fri, Nov 18, 2022 at 02:58:49AM +0000, Tian, Kevin wrote:
> > > > From: Jason Gunthorpe <jgg@nvidia.com>
> > > > Sent: Thursday, November 17, 2022 5:01 AM
> > > > index ca28a135b9675f..2fdff04000b326 100644
> > > > --- a/drivers/iommu/iommufd/Makefile
> > > > +++ b/drivers/iommu/iommufd/Makefile
> > > > @@ -5,6 +5,7 @@ iommufd-y := \
> > > > io_pagetable.o \
> > > > ioas.o \
> > > > main.o \
> > > > - pages.o
> > > > + pages.o \
> > > > + vfio_compat.o
> > > >
> > >
> > > move vfio_compat out of core? it's not required if VFIO
> > > is not configured.
> >
> > We can, but I don't know if we should. Compat ioctls are part of
> > /dev/iommu, and technically have nothing to do with VFIO. A native
> > iommufd application using VDPA could use them, if it wanted, for
> > instance.
> >
>
> I'm not sure whether that requires further VDPA support. Be safe
> I'd like VDPA to explicitly select vfio_compact when that new
> mixed scheme is supported.
>

This sounds strange. If I don't misunderstand the code, it tries to
provide ioctl compatibility with the VFIO container. I don't see how
it can be used for vDPA, the ioctls used by vDPA is not compatible
with VFIO.

Thanks