Re: [PATCH] powerpc/mce: save ignore_event flag unconditionally for UE

[Ganesh <ganeshgr@linux.ibm.com>]

On 4/20/21 12:54 PM, Santosh Sivaraj wrote:

> Hi Ganesh,
>
> Ganesh Goudar <ganeshgr@linux.ibm.com> writes:
>
>> When we hit an UE while using machine check safe copy routines,
>> ignore_event flag is set and the event is ignored by mce handler,
>> And the flag is also saved for defered handling and printing of
>> mce event information, But as of now saving of this flag is done
>> on checking if the effective address is provided or physical address
>> is calculated, which is not right.
>>
>> Save ignore_event flag regardless of whether the effective address is
>> provided or physical address is calculated.
>>
>> Without this change following log is seen, when the event is to be
>> ignored.
>>
>> [  512.971365] MCE: CPU1: machine check (Severe)  UE Load/Store [Recovered]
>> [  512.971509] MCE: CPU1: NIP: [c0000000000b67c0] memcpy+0x40/0x90
>> [  512.971655] MCE: CPU1: Initiator CPU
>> [  512.971739] MCE: CPU1: Unknown
>> [  512.972209] MCE: CPU1: machine check (Severe)  UE Load/Store [Recovered]
>> [  512.972334] MCE: CPU1: NIP: [c0000000000b6808] memcpy+0x88/0x90
>> [  512.972456] MCE: CPU1: Initiator CPU
>> [  512.972534] MCE: CPU1: Unknown
>>
>> Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
>> ---
>>   arch/powerpc/kernel/mce.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
>> index 11f0cae086ed..db9363e131ce 100644
>> --- a/arch/powerpc/kernel/mce.c
>> +++ b/arch/powerpc/kernel/mce.c
>> @@ -131,6 +131,8 @@ void save_mce_event(struct pt_regs *regs, long handled,
>>   	 * Populate the mce error_type and type-specific error_type.
>>   	 */
>>   	mce_set_error_info(mce, mce_err);
>> +	if (mce->error_type == MCE_ERROR_TYPE_UE)
>> +		mce->u.ue_error.ignore_event = mce_err->ignore_event;
>>   
>>   	if (!addr)
>>   		return;
>> @@ -159,7 +161,6 @@ void save_mce_event(struct pt_regs *regs, long handled,
>>   		if (phys_addr != ULONG_MAX) {
>>   			mce->u.ue_error.physical_address_provided = true;
>>   			mce->u.ue_error.physical_address = phys_addr;
>> -			mce->u.ue_error.ignore_event = mce_err->ignore_event;
>>   			machine_check_ue_event(mce);
>>   		}
>>   	}
> Small nit:
> Setting ignore event can happen before the phys_addr check, under the existing
> check for MCE_ERROR_TYPE_UE, instead of repeating the same condition again.

In some cases we may not get effective address also, so it is placed before effective
address check.

>
> Except for the above nit
>
> Reviewed-by: Santosh Sivaraj <santosh@fossix.org>
>
> Thanks,
> Santosh
>> -- 
>> 2.26.2