Re: [Qemu-devel] [PATCH/s390-next 3/3] s390x/flic: migrate ais states

[Halil Pasic]

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.

Regards,
Halil

>> +        return;
>> +    }
>> +
>> +    tmp->simm = ais.simm;
>> +    tmp->nimm = ais.nimm;
>> +}
>> +