Re: [PATCH v8 5/5] powerpc/hv-24x7: Update post_mobility_fixup() to handle migration

[kajoljain <kjain@linux.ibm.com>]

On 5/12/20 1:10 AM, Nathan Lynch wrote:
> Hello,
> 
> Kajol Jain <kjain@linux.ibm.com> writes:
>> Function 'read_sys_info_pseries()' is added to get system parameter
>> values like number of sockets and chips per socket.
>> and it gets these details via rtas_call with token
>> "PROCESSOR_MODULE_INFO".
>>
>> Incase lpar migrate from one system to another, system
>> parameter details like chips per sockets or number of sockets might
>> change. So, it needs to be re-initialized otherwise, these values
>> corresponds to previous system values.
>> This patch adds a call to 'read_sys_info_pseries()' from
>> 'post-mobility_fixup()' to re-init the physsockets and physchips values
>>
>> Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
>> ---
>>  arch/powerpc/platforms/pseries/mobility.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
> 
> Please cc me on patches for this code, thanks.

Hi Nathan,
	Thanks for reviewing the patch. I will cc you on next version of this patchset.
> 
> I see no technical problems with how this patch handles partition
> migration. However:
> 
> "Update post_mobility_fixup() to handle migration" is not an appropriate
> summary for this change. post_mobility_fixup() already handles
> migration. A better summary would be
> 
> "powerpc/pseries: update hv-24x7 info after migration"

Will update.

> 
> 
>> diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
>> index b571285f6c14..0fb8f1e6e9d2 100644
>> --- a/arch/powerpc/platforms/pseries/mobility.c
>> +++ b/arch/powerpc/platforms/pseries/mobility.c
>> @@ -42,6 +42,12 @@ struct update_props_workarea {
>>  #define MIGRATION_SCOPE	(1)
>>  #define PRRN_SCOPE -2
>>  
>> +#ifdef CONFIG_HV_PERF_CTRS
>> +void read_sys_info_pseries(void);
>> +#else
>> +static inline void read_sys_info_pseries(void) { }
>> +#endif
> 
> This should go in a header.
> 
> 
>>  static int mobility_rtas_call(int token, char *buf, s32 scope)
>>  {
>>  	int rc;
>> @@ -371,6 +377,16 @@ void post_mobility_fixup(void)
>>  	/* Possibly switch to a new RFI flush type */
>>  	pseries_setup_rfi_flush();
>>  
>> +	/*
>> +	 * In case an Lpar migrates from one system to another, system
>> +	 * parameter details like chips per sockets, cores per chip and
>> +	 * number of sockets details might change.
>> +	 * So, they needs to be re-initialized otherwise the
>> +	 * values will correspond to the previous system.
>> +	 * Call read_sys_info_pseries() to reinitialise the values.
>> +	 */
> 
> This is needlessly verbose; any literate reader of this code knows this
> is used immediately after resuming from a suspend (migration). If you
> give your hook a more descriptive name, the comment becomes unnecessary.
> 

Yes make sense, will update.

Thanks,
Kajol Jain

> 
>> +	read_sys_info_pseries();
>> +
>