Re: [PATCH v3] powerpc/papr_scm: Implement initial support for injecting smart errors

[Vaibhav Jain <vaibhav@linux.ibm.com>]

Hi Ira, Thanks for reviewing this patch.

Ira Weiny <ira.weiny@intel.com> writes:

> On Thu, Jan 13, 2022 at 05:32:52PM +0530, Vaibhav Jain wrote:
> [snip]
>
>>  
>> +/* Inject a smart error Add the dirty-shutdown-counter value to the pdsm */
>> +static int papr_pdsm_smart_inject(struct papr_scm_priv *p,
>> +				  union nd_pdsm_payload *payload)
>> +{
>> +	int rc;
>> +	u32 supported_flags = 0;
>> +	u64 mask = 0, override = 0;
>> +
>> +	/* Check for individual smart error flags and update mask and override */
>> +	if (payload->smart_inject.flags & PDSM_SMART_INJECT_HEALTH_FATAL) {
>> +		supported_flags |= PDSM_SMART_INJECT_HEALTH_FATAL;
>> +		mask |= PAPR_PMEM_HEALTH_FATAL;
>> +		override |= payload->smart_inject.fatal_enable ?
>> +			PAPR_PMEM_HEALTH_FATAL : 0;
>> +	}
>> +
>> +	if (payload->smart_inject.flags & PDSM_SMART_INJECT_BAD_SHUTDOWN) {
>> +		supported_flags |= PDSM_SMART_INJECT_BAD_SHUTDOWN;
>> +		mask |= PAPR_PMEM_SHUTDOWN_DIRTY;
>> +		override |= payload->smart_inject.unsafe_shutdown_enable ?
>> +			PAPR_PMEM_SHUTDOWN_DIRTY : 0;
>> +	}
>> +
>
> I'm struggling to see why there is a need for both a flag and an 8 bit 'enable'
> value?
>
This is to enable the inject/uninject error usecase with ndctl which
lets user select individual error conditions like bad_shutdown or
fatal-health state.

The nd_papr_pdsm_smart_inject.flag field indicates which error
conditions needs to be tweaked and individual __u8 fields like
'fatal_enable' are boolean values to indicate the inject/uninject state
of that error condition.

For e.g to uninject fatal-health and inject unsafe-shutdown following
nd_papr_pdsm_smart_inject payload can be sent:

{
.flags = PDSM_SMART_INJECT_HEALTH_FATAL |
       PDSM_SMART_INJECT_BAD_SHUTDOWN,
.fatal_enable = 0,
.unsafe_shutdown_enable = 1,
}


To just to inject fatal-health following nd_papr_pdsm_smart_inject
payload can be sent:

{
.flags = PDSM_SMART_INJECT_HEALTH_FATAL,
.fatal_enable = 1,
.unsafe_shutdown_enable = <dont-care>,
}


> Ira
>

-- 
Cheers
~ Vaibhav