[Intel-gfx] [PATCH v3 12/12] vfio/pci: Report dev_id in VFIO_DEVICE_GET_PCI_HOT_RESET_INFO

[Liu, Yi L]

> From: Alex Williamson <alex.williamson at redhat.com>
> Sent: Tuesday, April 18, 2023 12:11 PM
> 
[...]
>
> We haven't discussed how it fails when called on a group-opened device
> in a mixed environment.  I'd propose that the INFO ioctl behaves
> exactly as it does today, reporting group-id and BDF for each affected
> device.  However, the hot-reset ioctl itself is not extended to accept
> devicefd because there is no proof-of-ownership model for cdevs.
> Therefore even if the user could map group-id to devicefd, they get
> -EINVAL calling HOT_RESET with a devicefd when the ioctl is called from
> a group-opened device.  Thanks,

Will it be better to let userspace know it shall fail if invoking hot
reset due to no proof-of-ownership as it also has cdev devices? Maybe
the RESETTABLE flag should always be meaningful. Even if the calling
device of _INFO is group-opened device. Old user applications does not
need to check it as it will never have such mixed environment. But for
new applications or the applications that have been updated per latest
vfio uapi, it should strictly check this flag before going ahead to do
hot-reset.

Regards,
Yi Liu