Re: [kvm-unit-tests PATCH v8 11/12] s390x: css: msch, enable test

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

On 2020-06-09 09:47, Thomas Huth wrote:
> On 08/06/2020 10.13, Pierre Morel 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.
>> - If the command succeeds but subchannel is not enabled retry a
>>    predefined retries count.
>> - If the command fails, report the failure and do not retry, even
>>    if cc indicates a busy/status pending as we do not expect this.
>>
>> This tests the MSCH instruction to enable a channel succesfuly.
>> This some retries are done and in case of error, and if the retries
>> count is exceeded, a report is made.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   lib/s390x/css_lib.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
>>   s390x/css.c         | 18 ++++++++++++++
>>   2 files changed, 78 insertions(+)
>>
>> diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
>> index dc5a512..831a116 100644
>> --- a/lib/s390x/css_lib.c
>> +++ b/lib/s390x/css_lib.c
>> @@ -15,6 +15,7 @@
>>   #include <string.h>
>>   #include <interrupt.h>
>>   #include <asm/arch_def.h>
>> +#include <asm/time.h>
>>   
>>   #include <css.h>
>>   
>> @@ -68,3 +69,62 @@ out:
>>   		    scn, scn_found, dev_found);
>>   	return schid;
>>   }
>> +
>> +int css_enable(int schid)
>> +{
>> +	struct pmcw *pmcw = &schib.pmcw;
>> +	int retry_count = 0;
>> +	int cc;
>> +
>> +	/* Read the SCHIB for this subchannel */
>> +	cc = stsch(schid, &schib);
>> +	if (cc) {
>> +		report_info("stsch failed with cc=%d", cc);
>> +		return cc;
>> +	}
>> +
>> +	if (pmcw->flags & PMCW_ENABLE) {
>> +		report_info("stsch: sch %08x already enabled", schid);
>> +		return 0;
>> +	}
>> +
>> +retry:
>> +	/* Update the SCHIB to enable the channel */
>> +	pmcw->flags |= PMCW_ENABLE;
>> +
>> +	/* Tell the CSS we want to modify the subchannel */
>> +	cc = msch(schid, &schib);
>> +	if (cc) {
>> +		/*
>> +		 * If the subchannel is status pending or
>> +		 * if a function is in progress,
>> +		 * we consider both cases as errors.
>> +		 */
>> +		report_info("msch failed with cc=%d", cc);
>> +		return cc;
>> +	}
>> +
>> +	/*
>> +	 * Read the SCHIB again to verify the enablement
>> +	 */
>> +	cc = stsch(schid, &schib);
>> +	if (cc) {
>> +		report_info("stsch failed with cc=%d", cc);
>> +		return cc;
>> +	}
>> +
>> +	if (pmcw->flags & PMCW_ENABLE) {
>> +		report_info("Subchannel %08x enabled after %d retries",
>> +			    schid, retry_count);
>> +		return 0;
>> +	}
>> +
>> +	if (retry_count++ < MAX_ENABLE_RETRIES) {
>> +		mdelay(10); /* the hardware was not ready, give it some time */
>> +		goto retry;
>> +	}
>> +
>> +	report_info("msch: enabling sch %08x failed after %d retries. pmcw flags: %x",
>> +		    schid, retry_count, pmcw->flags);
>> +	return -1;
>> +}
>> diff --git a/s390x/css.c b/s390x/css.c
>> index f0e8f47..6f58d4a 100644
>> --- a/s390x/css.c
>> +++ b/s390x/css.c
>> @@ -40,11 +40,29 @@ static void test_enumerate(void)
>>   	}
>>   }
>>   
>> +static void test_enable(void)
>> +{
>> +	int cc;
>> +
>> +	if (!test_device_sid) {
>> +		report_skip("No device");
>> +		return;
>> +	}
>> +
>> +	cc = css_enable(test_device_sid);
>> +
>> +	if (cc)
>> +		report(0, "Failed to enable subchannel %08x", test_device_sid);
>> +	else
>> +		report(1, "Subchannel %08x enabled", test_device_sid);
> 
> Could you please write this as:
> 
> 	report(cc == 1, "Enable subchannel %08x", test_device_sid);
> 
> ... checking for a right value is the whole point of the first parameter
> of report() :-)
> 
>   Thanks,
>    Thomas
> 

OK, thanks,
Pierre

-- 
Pierre Morel
IBM Lab Boeblingen