On Thu, 13 Jul 2017 17:05:45 +0200
Christian Borntraeger <borntrae...@de.ibm.com> wrote:
> On 07/13/2017 04:49 PM, Dr. David Alan Gilbert wrote:
> > * Halil Pasic (pa...@linux.vnet.ibm.com) wrote:
> >>
> >>
> >> On 07/13/2017 02:27 PM, Cornelia Huck wrote:
> >>>> +static void kvm_flic_ais_pre_save(void *opaque)
> >>>> +{
> >>>> + KVMS390FLICStateMigTmp *tmp = opaque;
> >>>> + KVMS390FLICState *flic = tmp->parent;
> >>>> + struct kvm_s390_ais_all ais;
> >>>> + struct kvm_device_attr attr = {
> >>>> + .group = KVM_DEV_FLIC_AISM_ALL,
> >>>> + .addr = (uint64_t)&ais,
> >>>> + .attr = sizeof(ais),
> >>>> + };
> >>>> +
> >>>> + if (ioctl(flic->fd, KVM_GET_DEVICE_ATTR, &attr)) {
> >>>> + error_report("Failed to retrieve kvm flic ais states");
> >>> There's not much else we can do in that case, is there?
> >>>
> >>
> >> I think this is a very good question! The ioctl should not fail
> >> under any circumstances, but if it does we have a problem.
> >>
> >> Carrying on happily (what we do now) means effectively discarding
> >> ais state. In general just discarding state ain't a good idea.
> >>
> >> In particular it might be OK, but the patch should explain that!
> >>
> >> Regarding what could/should we do in such a case (instead
> >> of discarding state and carrying on happily) I don't know, so
> >> I tend to agree with you regarding 'not much else we can do'.
> >>
> >> Adding Dave and Juan. Maybe they can tell.
> >
> > I keep meaning to make the pre_save give a return value for failure,
> > but it hasn't currently got one.
>
> Would you accept patches for that?
>
> >
> > You could try something like:
> >
> > qemu_file_set_error(migrate_get_current()->to_dst_file, -EINVAL);
> >
> > I *think* the migration code should spot that before it finishes
> > but it might carry on for a little while before it does.
>
> I will keep this patch as is, since this is one of the "should not happen"
> cases.
>
Fine with me.
