On Wed, 3 Mar 2021 11:41:22 -0500 Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote: > > How do you exect userspace to react to this -ENODEV? > > The VFIO_DEVICE_RESET ioctl expects a return code. > The vfio_ap_mdev_reset_queues() function can return -EIO or > -EBUSY, so I would expect userspace to handle -ENODEV > similarly to -EIO or any other non-zero return code. I also > looked at all of the VFIO_DEVICE_RESET calls from QEMU to see > how the return from the ioctl call is handled: > > * ap: reports the reset failed along with the rc And carries on as if nothing happened. There is not much smart userspace can do in such a situation. Therefore the reset really should not fail. Please note that in this particular case, if the userspace would opt for a retry, we would most likely end up in a retry loop. > * ccw: doesn't check the rc > * pci: kind of hard to follow without digging deep, but definitely > handles non-zero rc. > > I think the caller should be notified whether the queues were > successfully reset or not, and why; in this case, the answer is > there are no devices to reset. That is the wrong answer. The ioctl is supposed to reset the ap_matrix_mdev device. The ap_matrix_mdev device still exists. Thus returning -ENODEV is bugous. Regards, Halil
