Re: [qemu-s390x] [Qemu-devel] [PATCH v3 6/7] s390x/kvm: handle AP instruction interception

[Halil Pasic]

On 03/26/2018 11:03 AM, Pierre Morel wrote:
>>> +int ap_device_handle_pqap(S390CPU *cpu)
>>> +{
>>> +    CPUS390XState *env = &cpu->env;
>>> +    int fc = 4 & (env->regs[0] >> 24);
>>> +
>>> +    /*
>>> +     * The Query Configuration Information (QCI) function (fc == 4) does 
>>> not
>>> +     * set a response code in reg 1, so check for that along with the
>>> +     * AP feature.
>>> +     */
>>> +    if ((fc != 4) && s390_has_feat(S390_FEAT_AP)) {
>>> +        env->regs[1] = 0x10000;
>>> +
>>> +        return 0;
>>> +    }
>> This would imply an operation exception in case fc==4, which sounds very
>> wrong.

Yes, operation exception is a wrong response under the condition
(fc == 4) && s390_has_feat(S390_FEAT_AP).

@David:
FYI Tony is likely to respond after Wednesday as he is on vacation right
now.

> 
> It depends but I think that the S390_FEAT_AP_QUERY_CONFIG_INFO must be tested
> to know what to answer.
> If the feature is there, QCI must be answered correctly.
> 
> there are also some error situations to handle in all three functions.
>

I agree. 
 
Regards,
Halil