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

[Santosh Sivaraj <santosh@fossix.org>]

Ganesh <ganeshgr@linux.ibm.com> writes:

> 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.

Yes, I forgot the last two lines in the changelog after I applied the patch :-)

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