Re: [kvm-unit-tests PATCH v3 7/9] s390x: css: msch, enable test

Pierre Morel
2019-12-10T09:03:31Z

On 2019-12-09 17:54, Cornelia Huck wrote:
> On Fri, 6 Dec 2019 17:26:26 +0100
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> A second step when testing the channel subsystem is to prepare a channel
>> for use.
>> This includes:
>> - Get the current SubCHannel Information Block (SCHIB) using STSCH
>> - Update it in memory to set the ENABLE bit
>> - Tell the CSS that the SCHIB has been modified using MSCH
>> - Get the SCHIB from the CSS again to verify that the subchannel is
>> enabled.
>>
>> This tests the success of the MSCH instruction by enabling a channel.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>> s390x/css.c | 39 +++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 39 insertions(+)
>>
>> diff --git a/s390x/css.c b/s390x/css.c
>> index 3d4a986..4c0031c 100644
>> --- a/s390x/css.c
>> +++ b/s390x/css.c
>> @@ -58,11 +58,50 @@ static void test_enumerate(void)
>> report("Tested %d devices, %d found", 1, scn, found);
>> }
>>
>> +static void test_enable(void)
>> +{
>> + struct pmcw *pmcw = &schib.pmcw;
>> + int cc;
>> +
>> + if (!test_device_sid) {
>> + report_skip("No device");
>> + return;
>> + }
>> + /* Read the SCIB for this subchannel */
>
> s/SCIB/SCHIB/

yes

>
>> + cc = stsch(test_device_sid, &schib);
>> + if (cc) {
>> + report("stsch cc=%d", 0, cc);
>> + return;
>> + }
>> + /* Update the SCHIB to enable the channel */
>> + pmcw->flags |= PMCW_ENABLE;
>> +
>> + /* Tell the CSS we want to modify the subchannel */
>> + cc = msch(test_device_sid, &schib);
>> + if (cc) {
>> + report("msch cc=%d", 0, cc);
>
> So you expect the subchannel to be idle? Probably true, especially as
> QEMU has no reason to post an unsolicited interrupt for a test device.
>
>> + return;
>> + }
>> +
>> + /* Read the SCHIB again to verify the enablement */
>> + cc = stsch(test_device_sid, &schib);
>> + if (cc) {
>> + report("stsch cc=%d", 0, cc);
>> + return;
>> + }
>> + if (!(pmcw->flags & PMCW_ENABLE)) {
>> + report("Enable failed. pmcw: %x", 0, pmcw->flags);
>
> This check is fine when running under KVM. If this test is modified to
> run under z/VM in the future, you probably should retry here: I've seen
> the enable bit 'stick' only after the second msch() there.

Oh. Thanks, may be I can loop with a delay and count.
If I need to do this may be I need to create dedicated sub-functions to
include the sanity tests.

>
>> + return;
>> + }
>> + report("Tested", 1);
>> +}
>> +
>> static struct {
>> const char *name;
>> void (*func)(void);
>> } tests[] = {
>> { "enumerate (stsch)", test_enumerate },
>> + { "enable (msch)", test_enable },
>> { NULL, NULL }
>> };
>>
>

--
Pierre Morel
IBM Lab Boeblingen