Re: [kvm-unit-tests PATCH v2 3/4] s390x: topology: Check the Perform Topology Function

Pierre Morel
2021-08-12T11:40:11Z

On 8/12/21 11:38 AM, Janosch Frank wrote:
> On 8/10/21 6:22 PM, Pierre Morel wrote:
>> We check the PTF instruction.
>>
>> - We do not expect to support vertical polarization.
>
> KVM does not support vertical polarization and we don't expect it to be
> added in the future?

OK

>
>>
>> - We do not expect the Modified Topology Change Report to be
>> pending or not at the moment the first PTF instruction with
>> PTF_CHECK function code is done as some code already did run
>> a polarization change may have occur.
>
> ENOPARSE

OK I find another way to explain:

"
The Topology changes if the topology of the real CPUs backing the vCPUs
changes.
This can happen between the initialization of the VM and the start of
the guest.
As a consequence we can not expect the result of the first PTF instruction.
"
...
>> + /*
>> + * In the LPAR we can not assume the state of the polarizatiom
>
> polarization

yes

>
>> + * at this moment.
>> + * Let's skip the tests for LPAR.
>> + */
>
> Any idea what happens on z/VM?
> We don't necessarily need to support z/VM but we at least need to skip
> like we do on lpar :-)

No, I do not know.
Then OK we skip the test for zVM too

>
> Maybe also add a TODO, so we know we could improve the test?
>
>> + if (machine_level < 3)
>> + goto end;
>> +
>
> Add comments:
> We're always horizontally polarized in KVM.

OK

>
>> + cc = ptf(PTF_REQ_HORIZONTAL, &rc);
>> + report(cc == 2 && rc == PTF_ERR_ALRDY_POLARIZED,
>> + "PTF horizontal already configured");
>> +
>
> KVM doesn't support vertical polarization.

OK too

>
>> + cc = ptf(PTF_REQ_VERTICAL, &rc);
>> + report(cc == 2 && rc == PTF_ERR_NO_REASON,
>> + "PTF vertical non possible");
>
> s/non/not/

yes, seems I forgot to change this.

...

Thanks,
Pierre

--
Pierre Morel
IBM Lab Boeblingen