Messages in this thread |  | | Date | Tue, 30 Jan 2018 12:18:48 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel |
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On Tue, Jan 30, 2018 at 11:03:50AM +0000, David Woodhouse wrote: > I pondered that, but I didn't like it. I didn't want to always *force* > those features on, for all CPUs, just because they happened to be > discovered at boot time on the first CPU (which *did* have its > microcode updated by the crappy BIOS, while the others didn't). > > I strongly suspect that's purely an academic concern, and we mostly > check boot_cpu_has() and never even *notice* if secondary CPUs don't > match. I just didn't want to make that *worse*. It tickled my OCD.
Well, you need to do it because those bits are AMD-specific and they are not set in the Intel CPUID leaf and identify_cpu() towards the end takes care of "ironing" all those bits out which are not part of the common feature set and which get_cpu_cap() has *not* read out from CPUID.
It is one of those I-told-you-so moments when I suggested to make the visible feature bits the artificial ones and have the *actual* hardware ones set those.
:-)
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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