[v2 09/12] powerpc/mce: Enable MCE notifiers in external modules

[Mahesh Jagannath Salgaonkar]

On 7/2/19 11:47 AM, Nicholas Piggin wrote:
> Santosh Sivaraj's on July 2, 2019 3:19 pm:
>> From: Reza Arbab <arbab at linux.ibm.com>
>>
>> Signed-off-by: Reza Arbab <arbab at linux.ibm.com>
>> ---
>>  arch/powerpc/kernel/exceptions-64s.S | 6 ++++++
>>  arch/powerpc/kernel/mce.c            | 2 ++
>>  2 files changed, 8 insertions(+)
>>
>> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
>> index c83e38a403fd..311f1392a2ec 100644
>> --- a/arch/powerpc/kernel/exceptions-64s.S
>> +++ b/arch/powerpc/kernel/exceptions-64s.S
>> @@ -458,6 +458,12 @@ EXC_COMMON_BEGIN(machine_check_handle_early)
>>  	bl	machine_check_early
>>  	std	r3,RESULT(r1)	/* Save result */
>>  
>> +	/* Notifiers may be in a module, so enable virtual addressing. */
>> +	mfmsr	r11
>> +	ori	r11,r11,MSR_IR
>> +	ori	r11,r11,MSR_DR
>> +	mtmsr	r11
> 
> Can't do this, we could take a machine check somewhere the MMU is
> not sane (in fact the guest early mce handling that was added recently
> should not be enabling virtual mode either, which needs to be fixed).

Looks like they need this to be able to run notifier chain which may
fail in real mode.

> 
> Thanks,
> Nick
>