Re: [kvm-unit-tests PATCH v4 6/9] s390x: css: stsch, enumeration test

[Pierre Morel <pmorel@linux.ibm.com>]

On 2019-12-12 11:18, Cornelia Huck wrote:
> On Wed, 11 Dec 2019 16:46:07 +0100
> Pierre Morel <pmorel@linux.ibm.com> wrote:
> 
>> First step for testing the channel subsystem is to enumerate the css and
>> retrieve the css devices.
>>
>> This tests the success of STSCH I/O instruction, we do not test the
>> reaction of the VM for an instruction with wrong parameters.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   lib/s390x/css.h     |  1 +
>>   s390x/Makefile      |  2 ++
>>   s390x/css.c         | 88 +++++++++++++++++++++++++++++++++++++++++++++
>>   s390x/unittests.cfg |  4 +++
>>   4 files changed, 95 insertions(+)
>>   create mode 100644 s390x/css.c
> 
>> diff --git a/s390x/css.c b/s390x/css.c
>> new file mode 100644
>> index 0000000..dfab35f
>> --- /dev/null
>> +++ b/s390x/css.c
>> @@ -0,0 +1,88 @@
>> +/*
>> + * Channel Subsystem tests
>> + *
>> + * Copyright (c) 2019 IBM Corp
>> + *
>> + * Authors:
>> + *  Pierre Morel <pmorel@linux.ibm.com>
>> + *
>> + * This code is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2.
>> + */
>> +
>> +#include <libcflat.h>
>> +#include <alloc_phys.h>
>> +#include <asm/page.h>
>> +#include <string.h>
>> +#include <interrupt.h>
>> +#include <asm/arch_def.h>
>> +#include <asm/time.h>
>> +
>> +#include <css.h>
>> +
>> +#define SID_ONE		0x00010000
>> +
>> +static struct schib schib;
>> +static int test_device_sid;
>> +
>> +static void test_enumerate(void)
>> +{
>> +	struct pmcw *pmcw = &schib.pmcw;
>> +	int cc;
>> +	int scn;
>> +	int scn_found = 0;
>> +
>> +	for (scn = 0; scn < 0xffff; scn++) {
>> +		cc = stsch(scn|SID_ONE, &schib);
>> +		switch (cc) {
>> +		case 0:		/* 0 means SCHIB stored */
>> +			break;
>> +		case 3:		/* 3 means no more channels */
>> +			goto out;
>> +		default:	/* 1 or 2 should never happened for STSCH */
>> +			report(0, "Unexpected cc=%d on scn 0x%x", cc, scn);
> 
> Spell out "subchannel number"?

Yes I can do this.

> 
>> +			return;
>> +		}
>> +		if (cc)
>> +			break;
> 
> Isn't that redundant?
fully.

> 
>> +		/* We silently only support type 0, a.k.a. I/O channels */
> 
> s/silently/currently/ ?

OK

> 
>> +		if (PMCW_CHANNEL_TYPE(pmcw) != 0)
>> +			continue;
>> +		/* We ignore I/O channels without valid devices */
>> +		if (!(pmcw->flags & PMCW_DNV))
>> +			continue;
>> +		/* We keep track of the first device as our test device */
>> +		if (!test_device_sid)
>> +			test_device_sid = scn|SID_ONE;
>> +		scn_found++;
>> +	}
>> +out:
>> +	if (!scn_found) {
>> +		report(0, "Devices, Tested: %d, no I/O type found", scn);
> 
> It's no I/O _devices_ found, isn't it? There might have been I/O
> subchannels, but none with a valid device...

yes, I will update the stats.

> 
>> +		return;
>> +	}
>> +	report(1, "Devices, tested: %d, I/O type: %d", scn, scn_found);
> 
> As you're testing this anyway: what about tracking _all_ numbers here?
> I.e., advance a counter for I/O subchannels as well, even if !dnv, and
> have an output like >
> "Tested subchannels: 20, I/O subchannels: 18, I/O devices: 10"
> 
> or so?

Yes, will do.


> 
>> +}
>> +
>> +static struct {
>> +	const char *name;
>> +	void (*func)(void);
>> +} tests[] = {
>> +	{ "enumerate (stsch)", test_enumerate },
>> +	{ NULL, NULL }
>> +};
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +	int i;
>> +
>> +	report_prefix_push("Channel Sub-System");
> 
> s/Channel Sub-System/Channel Subsystem/ ?

OK, (it was because of "CSS").

> 
>> +	for (i = 0; tests[i].name; i++) {
>> +		report_prefix_push(tests[i].name);
>> +		tests[i].func();
>> +		report_prefix_pop();
>> +	}
>> +	report_prefix_pop();
>> +
>> +	return report_summary();
>> +}
> 
> This basically looks sane to me now.
> 
> Just some additional considerations (we can do that on top, no need to
> do surgery here right now):
> 
> I currently have the (not sure how sensible) idea to add some optional
> testing for vfio-ccw, and this would obviously need some I/O routines as
> well. So, in the long run, it would be good if something like this
> stsch-loop could be factored out to a kind of library function. Just
> some thoughts for now :)
> 

Yes, could be useful.

Thanks,
Regards,
Pierre


-- 
Pierre Morel
IBM Lab Boeblingen