[PATCH 05/13] powerpc/mce: Allow notifier callback to handle MCE

[Mahesh Jagannath Salgaonkar]

On 6/23/19 7:44 AM, Reza Arbab wrote:
> Hi Mahesh,
> 
> On Fri, Jun 21, 2019 at 12:35:08PM +0530, Mahesh Jagannath Salgaonkar
> wrote:
>> On 6/21/19 6:27 AM, Santosh Sivaraj wrote:
>>> -    blocking_notifier_call_chain(&mce_notifier_list, 0, &evt);
>>> +    rc = blocking_notifier_call_chain(&mce_notifier_list, 0, evt);
>>> +    if (rc & NOTIFY_STOP_MASK) {
>>> +        evt->disposition = MCE_DISPOSITION_RECOVERED;
>>> +        regs->msr |= MSR_RI;
>>
>> What is the reason for setting MSR_RI ? I don't think this is a good
>> idea. MSR_RI = 0 means system got MCE interrupt when SRR0 and SRR1
>> contents were live and was overwritten by MCE interrupt. Hence this
>> interrupt is unrecoverable irrespective of whether machine check handler
>> recovers from it or not.
> 
> Good catch! I think this is an artifact from when I was first trying to
> get all this working.
> 
> Instead of setting MSR_RI, we should probably just check for it. Ie,
> 
>     if ((rc & NOTIFY_STOP_MASK) && (regs->msr & MSR_RI)) {
>         evt->disposition = MCE_DISPOSITION_RECOVERED;

Yup, looks good to me.

Thanks,
-Mahesh.