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

Pierre Morel
2019-12-12T13:50:56Z

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