On Mon, 30 Jul 2018 13:24:24 +0200
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
> On 30/07/2018 11:49, Cornelia Huck wrote:
> > On Fri, 27 Jul 2018 16:17:47 +0200
> > Halil Pasic <pasic@xxxxxxxxxxxxx> wrote:
> >
> >> On 07/26/2018 09:54 PM, Christian Borntraeger wrote:
> >>> @@ -65,6 +66,21 @@ static int vfio_ap_matrix_dev_create(void)
> >>> {
> >>> int ret;
> >>>
> >>> + mutex_init(&matrix_dev.lock);
> >>> + INIT_LIST_HEAD(&matrix_dev.mdev_list);
> >>> +
> >>> + /* Test if PQAP(QCI) instruction is available */
> >>> + if (test_facility(12)) {
> >>> + ret = ap_qci(&matrix_dev.info);
> >>> + if (ret && (ret != -EOPNOTSUPP)) {
> >> After Connie's curiosity was piqued I gave this another look. If
> >> I read the ap_qci() documentation and code correctly, it can return
> >> either 0 or -EOPNOTSUPP, but nothing else. So basically this
> >> is a dead branch.
> > Can it return -EOPNOTSUPP if facility 12 is present?
>
> I do not think it is reasonable to continue if
> we stated that facility 12 is present but the ap_qci function failed.
>
> So I propose that we return an error and break the insmod.
So, would that be a bug? If yes, returning an error makes sense.
(I can't check the documentation to find out about the interaction
between facility 12 and PQAP(QCI)...)
