Re: [RFC PATCH 5/7] powerpc/book3s: Don't turn on the MSR[ME] bit until opal processes the reason.

On Tue, 21 Feb 2017 09:47:53 +0530
Mahesh Jagannath Salgaonkar [off-list ref] wrote:

On 02/21/2017 08:17 AM, Nicholas Piggin wrote:

quoted

On Tue, 21 Feb 2017 07:22:56 +0530
Mahesh J Salgaonkar [off-list ref] wrote:
  

quoted

From: Mahesh Salgaonkar <redacted>

Delay it until we are done with machine_check_early() call. Turn on MSR[ME]
once opal is done with processing MCE.  

Why? This seems like quite a regression -- the MCE handler today
has about 60 instructions and 30 l/st with ME clear.  

I understand that this is bit long window. But we are in MCE handling
code and if we hit MCE while doing that we may anyway end up with
recursive MCE interrupts without really be able to recover from it.

There is careful code to handle recursive machine checks though.
Things should be structured so we will handle recursive MCEs and
recover/fail/checkstop properly.

Instead lets risk checkstop which would get us rebooted with hostboot
throwing proper error call out.

I'd like more justification for the proposed change. How is it an
improvement?

Thanks,
Nick