[Intel-gfx] [PATCH v3 05/15] kvm/vfio: Accept vfio device file from userspace

[Liu, Yi L]

> From: Jason Gunthorpe <jgg at nvidia.com>
> Sent: Wednesday, February 15, 2023 8:18 AM
> 
> On Tue, Feb 14, 2023 at 04:42:35PM -0700, Alex Williamson wrote:
> 
> > A device file opened through a group could be passed through this
> > interface though, right?
> 
> Yes, I think so
> 
> > Do we just chalk that up to user error?  Maybe the SPAPR extension
> > at least needs to be documented as relying on registering groups
> > rather than devices.
> 
> The way these APIs work is you have to pass the same FD to all of
> them. The SPAPR stuff is no different, if you used a cdev with
> KVM_DEV_VFIO_GROUP_ADD then you have to use the same cdev fd with
> the
> SPAPR group_fd. Yi just didn't rename it.

This is because SPAPR cannot accept cdev fd yet. It explicitly requires
group fd and get iommu_group during the handling.

Regards,
Yi Liu