Re: [kvm-unit-tests PATCH v2 6/9] s390x: css: stsch, enumeration test

Pierre Morel
2019-12-02T18:34:07Z

On 2019-12-02 19:15, Cornelia Huck wrote:
> On Mon, 2 Dec 2019 18:53:16 +0100
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> On 2019-12-02 15:22, Cornelia Huck wrote:
>>> On Thu, 28 Nov 2019 13:46:04 +0100
>>> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>>>> +static int test_device_sid;
>>>> +
>>>> +static void test_enumerate(void)
>>>> +{
>>>> + struct pmcw *pmcw = &schib.pmcw;
>>>> + int sid;
>>>> + int ret, i;
>>>> + int found = 0;
>>>> +
>>>> + for (sid = 0; sid < 0xffff; sid++) {
>>>> + ret = stsch(sid|SID_ONE, &schib);
>>>
>>> This seems a bit odd. You are basically putting the subchannel number
>>> into sid, OR in the one, and then use the resulting value as the sid
>>> (subchannel identifier).
>>>
>>>> + if (!ret && (pmcw->flags & PMCW_DNV)) {
>>>> + report_info("SID %04x Type %s PIM %x", sid,
>>>
>>> That's not a sid, but the subchannel number (see above).
>>>
>>>> + Channel_type[pmcw->st], pmcw->pim);
>>>> + for (i = 0; i < 8; i++) {
>>>> + if ((pmcw->pim << i) & 0x80) {
>>>> + report_info("CHPID[%d]: %02x", i,
>>>> + pmcw->chpid[i]);
>>>> + break;
>>>> + }
>>>> + }
>>>> + found++;
>>>> +
>>>> + }
>>>
>>> Here, you iterate over the 0-0xffff range, even if you got a condition
>>> code 3 (indicating no more subchannels in that set). Is that
>>> intentional?
>>
>> I thought there could be more subchannels.
>> I need then a break in the loop when this happens.
>> I will reread the PoP to see how to find that no more subchannel are in
>> that set.
>
> The fact that cc 3 for stsch == no more subchannels is unfortunately a
> bit scattered across the PoP :/ Dug it out some time ago, maybe it's
> still in the archives somewhere...

So the the subchannel are always one after the other?

>
>>
>>>
>>>> + if (found && !test_device_sid)
>>>> + test_device_sid = sid|SID_ONE;
>>>
>>> You set test_device_sid to the last valid subchannel? Why?
>>
>> The last ? I wanted the first one
>
> It is indeed the first one, -ENOCOFFEE.

Would never happend to me.

>
>>
>> I wanted something easy but I should have explain.
>>
>> To avoid doing complicated things like doing a sense on each valid
>> subchannel I just take the first one.
>> Should be enough as we do not go to the device in this test.
>
> Yes; but you plan to reuse that code, don't you?

yes, so I must think about this

>
>>
>>>
>>>> + }
>>>> + if (!found) {
>>>> + report("Found %d devices", 0, found);
>
> Now that I look at this again: If you got here, you always found 0
> devices, so that message is not super helpful :)

yes, found is too much.
A cut and past from the time I was happy to find even one! :)

>
>>>> + return;
>>>> + }
>>>> + ret = stsch(test_device_sid, &schib);
>>>
>>> Why do you do a stsch() again?
>>
>> right, no need.
>> In an internal version I used to print some informations from the SCHIB.
>> Since in between I overwrote the SHIB, I did it again.
>> But in this version; no need.
>
> You could copy the schib of the subchannel to be tested to a different
> place, but I'm not sure it's worth it.
>
>>
>>>
>>>> + if (ret) {
>>>> + report("Err %d on stsch on sid %08x", 0, ret, test_device_sid);
>>>> + return;
>>>> + }
>>>> + report("Tested", 1);
>>>> + return;
>>>
>>> I don't think you need this return statement.
>>
>> right I have enough work. :)
>>
>>>
>>> Your test only enumerates devices in the first subchannel set. Do you
>>> plan to enhance the test to enable the MSS facility and iterate over
>>> all subchannel sets?
>>
>> Yes, it is something we can do in a following series
>
> Sure, just asked out of interest :)
>

Thanks,

Regards,
Pierre

--
Pierre Morel
IBM Lab Boeblingen