Messages in this thread | | | Date | Thu, 25 Sep 2014 10:51:58 +0200 | From | Borislav Petkov <> | Subject | Re: x86, microcode: BUG: microcode update that changes x86_capability |
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On Wed, Sep 24, 2014 at 11:56:58AM -0300, Henrique de Moraes Holschuh wrote: > I don't know about AMD, but on Intel, the time it takes to update the > microcode on a core is anything but negligible[1], so the microcode > version skew window still exists, and it is not small. It is much smaller > than it once was, but it is still there.
I think that window is unsafe but yeah, we probably should take your empirical observation as good enough for now.
> But IMHO we still need to detect and do something smart when > x86_capability changes due to a microcode update. > > And I'd really prefer it to be "update x86_capability, warn the user and > carry on" for anything that is not going to crash the kernel.
The problem is with hiding CPUID bits and userspace using HLE after having detected it previously. I think we'll be on the safe side if we reboot thus the suggestion to the user that rebooting should be done ASAP.
-- Regards/Gruss, Boris. --
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