[Intel-gfx] [PATCH v4 09/19] vfio/pci: Accept device fd for hot reset

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu at intel.com>
> Sent: Friday, February 24, 2023 11:44 AM
> > > Upon reflection we can probably make it even simpler and just have a 0
> > > length fd array mean to use the iommufd the vfio_device is already
> > > associated with
> > >
> > > And the check for correctness can be simplified to simply see if each
> > > vfio_device in the dev_set is attached to the same iommufd ctx
> > > pointer instead of searching the xarray.
> 
> How about the hot reset info path? We can still keep reporting the
> current information to userspace. Isn't it?

No need to change that. It's already reported per device.

> 
> another tricky question. If user passess iommufd down for reset
> in the vfio iommufd compatible mode, should we support it as
> well?
> 

I don't see why we want to ban it. It does change the result from
error (vfio container) to success (iommufd vfio-compat) when using
the container fd/iommufd. But do we actually have a use case
relying on such error pattern?

On the other hand an user who knows the presence of vfio-compat
should be allowed to pass iommufd to reset even when it still uses
the legacy group/container interfaces.