Re: [PATCH -v2] x86/boot/compressed: Register dummy NMI handler in EFI boot loader, to avoid kdump crashes

From: Borislav Petkov
Date: Tue Jan 10 2023 - 11:09:42 EST


On Tue, Jan 10, 2023 at 01:57:05PM +0100, Borislav Petkov wrote:
> I'm doubtful now as you're injecting errors so you're not really in #MC context
> but in this contrived context which is actually an NMI one. So we need to think
> about how to fix this case.

I did some more thinking:

*if* this really is a real issue - and not some silly qemu games - then
native_machine_crash_shutdown() does all the cleanup before the kdump kernel is
started.

Any NMI clearing, maybe using iret_to_self() etc, #MC resetting etc should
happen there and not anywhere else.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette