Messages in this thread | | | Date | Wed, 21 May 2014 15:42:24 +0200 (CEST) | From | Jiri Kosina <> | Subject | Re: 64bit x86: NMI nesting still buggy? |
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On Tue, 29 Apr 2014, Steven Rostedt wrote:
> Note, if this were true, then the x86_64 hardware would be extremely > buggy. That's because NMIs are not made to be nested. If SMM's come in > during an NMI and re-enables the NMI, then *all* software would break. > That would basically make NMIs useless. > > The only time I've ever witness problems (and I stress NMIs all the > time), is when the NMI itself does a fault. Which my patch set handles > properly. I've also stressed this on boxes that do have SMIs and SMMs. > > Now, you can have a bad BIOS that does re-enable NMIs from SMMs or > SMIs, but then you need to take that up with your vendor.
Alright, Andy's iret optimization efforts do immediately bring a followup question -- why is this not a problem with iret-based return from #MC possibly interrupting NMI?
-- Jiri Kosina SUSE Labs
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