RE: [PATCH v5 22/34] x86/fred: FRED initialization code

[Li, Xin3]

> > If there is no other concrete reason other than overflowing for
> > assigning NMI and #DB with a stack level > 0, #VE should also be
> > assigned with a stack level > 0, and #BP too. #VE can happen anytime
> > and anywhere, so it is subject to overflowing too.
> 
> So #BP needs the stack-gap (redzone) for text_poke_bp().
> 
> #BP can end up in kprobes which can then end up in ftrace/perf, depending on
> how it's all wired up.
> 
> #VE is currently a trainwreck vs NMI/MCE, but I think FRED solves the worst of
> that. I'm not exactly sure how deep the #VE handler goes.
> 

VE under IDT is *not* using an IST, we need some solid rationales here.

Thanks!
  Xin