Re: [RFC] #MC mess

[Peter Zijlstra]

On Tue, Feb 18, 2020 at 08:11:10PM +0000, Luck, Tony wrote:
> > Then please rewrite the #MC entry code to deal with nested exceptions
> > unmasking the MCE, very similr to NMI.
> 
> #MC doesn't work like NMI.  It isn't enabled by IRET.  Nested #MC cause an
> immediate reset.  Detection of nested case is by IA32_MCG_STATUS.MCIP.
> We don't clear MCG_STATUS until we are ready to return from the machine
> check handler.

Ooh, excellent! That saves a whole heap of problems.

Then I suppose we should work at getting in_nmi() set. Let me have
another look at things.