[v3 PATCH 4/5] powerpc/pseries: Dump and flush SLB contents on SLB MCE errors.

[Aneesh Kumar K.V]

On 06/12/2018 07:17 PM, Michael Ellerman wrote:
> Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com> writes:
>> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
>> index 2edc673be137..e56759d92356 100644
>> --- a/arch/powerpc/platforms/pseries/ras.c
>> +++ b/arch/powerpc/platforms/pseries/ras.c
>> @@ -422,6 +422,31 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
>>   	return 0; /* need to perform reset */
>>   }
>>   
>> +static int mce_handle_error(struct rtas_error_log *errp)
>> +{
>> +	struct pseries_errorlog *pseries_log;
>> +	struct pseries_mc_errorlog *mce_log;
>> +	int disposition = rtas_error_disposition(errp);
>> +	uint8_t error_type;
>> +
>> +	pseries_log = get_pseries_errorlog(errp, PSERIES_ELOG_SECT_ID_MCE);
>> +	if (pseries_log == NULL)
>> +		goto out;
>> +
>> +	mce_log = (struct pseries_mc_errorlog *)pseries_log->data;
>> +	error_type = rtas_mc_error_type(mce_log);
>> +
>> +	if ((disposition == RTAS_DISP_NOT_RECOVERED) &&
>> +			(error_type == PSERIES_MC_ERROR_TYPE_SLB)) {
>> +		slb_dump_contents();
>> +		slb_flush_and_rebolt();
> 
> Aren't we back in virtual mode here?
> 
> Don't we need to do the flush in real mode before turning the MMU back
> on. Otherwise we'll just take another multi-hit?
> 

slb_flush_and_rebolt does slbia, which keeps slb index 0. So kernel code 
should not get another slb miss. We also make sure we don't touch stack 
in slb_flush_and_rebolt(). So we flush everything and put vmalloc and 
stack back. That should be ok with MMU on?

-aneesh