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.

With IDT, both #VE and #BP do not use IST, but NMI, #DB, #MC and #DF do.

Let's keep this "secret" logic for now, i.e., not change the stack levels
for #VE and #BP at this point. We can do "optimization", i.e., change them
later :).