Messages in this thread | | | Date | Fri, 19 Sep 2014 17:00:42 +0200 | From | Borislav Petkov <> | Subject | Re: x86, microcode: BUG: microcode update that changes x86_capability |
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On Fri, Sep 19, 2014 at 07:54:14AM -0500, Chuck Ebbert wrote: > Assuming we can identify all the affected models and steppings, maybe > something like this would work: > > 1) Refuse to finish booting if a microcode update that disables TSX > isn't applied before userspace starts running on those CPUs.
Well, I think when we're booting, we would have already applied the early microcode, no? Because then it is a non-issue.
> 2) Don't allow a late update if TSX is still enabled on those > processors.
Yeah, so the use case I have in mind is when a long-running machine wants to apply microcode and this microcode disables CPUID bits and instructions. And the machine cannot be rebooted.
I guess in that case we would have to issue a warning only on the affected processors that a rebooted is mandatory and fail the update... Maybe something like that.
> (1) could be overridden by a command line option for people who want > to develop TSX code.
The way I understand it, those people shouldn't apply the microcode patch at all.
-- Regards/Gruss, Boris. --
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