On Wed, Nov 05, 2025 at 01:48:29PM -0700, Alex Williamson wrote:
> On Mon, 3 Nov 2025 07:39:37 +0000
> Pranjal Shrivastava <[email protected]> wrote:
> 
> > On Thu, Oct 23, 2025 at 08:09:28PM -0300, Jason Gunthorpe wrote:
> > > Remove the fallback through the ioctl callback, no drivers use this now.
> > > 
> > > Signed-off-by: Jason Gunthorpe <[email protected]>
> > > ---
> > >  drivers/vfio/vfio_main.c | 8 ++++----
> > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> > > index a390163ce706c4..f056e82ba35075 100644
> > > --- a/drivers/vfio/vfio_main.c
> > > +++ b/drivers/vfio/vfio_main.c
> > > @@ -1297,13 +1297,13 @@ static long vfio_device_fops_unl_ioctl(struct 
> > > file *filep,
> > >           break;
> > >  
> > >   case VFIO_DEVICE_GET_REGION_INFO:
> > > -         if (!device->ops->get_region_info)
> > > -                 goto ioctl_fallback;
> > > -         ret = device->ops->get_region_info(device, uptr);
> > > +         if (unlikely(!device->ops->get_region_info))
> > > +                 ret = -EINVAL;  
> 
> Nit, typically I would have expected a success oriented flow, ie.
> 
>               if (likely(device->ops->get_region_info))
>                       ret = device->ops->get_region_info(device, uptr);
>               else
>                       ret = -EINVAL;
> 
> But it goes away in the next patch, so *shrug*.

Yeah, still I can edit it..

> > Nit: Let's also add a warn/err log here highliting that the device
> > doesn't populate the get_region_info op?
> 
> Are devices required to implement regions?  If so, it'd be more
> appropriate to fail the device registration in __vfio_register_dev()
> for the missing op than wait for an ioctl.  However, here in the device
> agnostic layer of vfio, I think the answer leans more towards no, we
> could theoretically have a device with no regions.  We also want to be
> careful not to introduce a WARN_ON that's user trigger'able.  Thanks,

Yeah, I had the same thought, so lets leave this. If we do want a warn
it should be in registration.

A device without regions does not seem useful, but also it doesn't
malfunction if someone does want to do that.

Thanks,
Jason

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