Re: [PATCH v2 10/10] vfio/pci: Add VFIO_DEVICE_GET_PCI_HOT_RESET_GROUP_INFO

[Alex Williamson <alex.williamson@redhat.com>]

On Thu, 30 Mar 2023 19:44:55 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Thu, Mar 30, 2023 at 12:48:03PM +0000, Liu, Yi L wrote:
> > +	/*
> > +	 * If dev_id is needed, fill in the dev_id field, otherwise
> > +	 * fill in group_id.
> > +	 */
> > +	if (fill->require_devid) {
> > +		/*
> > +		 * Report the devices that are opened as cdev and have
> > +		 * the same iommufd with the fill->iommufd.  Otherwise,
> > +		 * just fill in an IOMMUFD_INVALID_ID.
> > +		 */
> > +		vdev = vfio_pci_find_device_in_devset(dev_set, pdev);
> > +		if (vdev && !vfio_device_cdev_opened(vdev) &&
> > +		    fill->iommufd == vfio_iommufd_physical_ictx(vdev))
> > +			vfio_iommufd_physical_devid(vdev, &fill->devices[fill->cur].dev_id);
> > +		fill->devices[fill->cur].dev_id = IOMMUFD_INVALID_ID;  
> 
> This needs an else?
> 
> I suggest to check for VFIO_PCI_HOT_RESET_FLAG_IOMMUFD_DEV_ID on input
> as well. I know the old kernels don't enforce this but at least we
> could start enforcing it going forward so that the group path would
> reject it to catch userspace bugs.
> 
> May as well fix it up to fully validate the flags

Is this under the guise of "if nobody complains it's ok, otherwise
revert" plan?  We report dev-id based on the nature of the device, not
the provided flags, so I'm not sure I follow how this protects the group
path, unless we've failed to clear the output flags on that path with
this change.  Thanks,

Alex