Messages in this thread | | | Date | Fri, 26 Jan 2018 23:10:26 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/cpufeatures: Cleanup AMD speculation feature bits |
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On Fri, Jan 26, 2018 at 09:59:44PM +0000, David Woodhouse wrote: > If we wanted to do this kind of thing, we'd do it the other way round. > Turn the *Intel* feature into both 'IBRS' and 'IBPB' CPU-visible > features, and have those defined in the AMD word.
You lost me here: have those defined in the AMD word?
> Then use virtual bits with "" for the software features, since we > don't want *those* to appear in /proc/cpuinfo.
Whatever we do, I think it would be most consistent to have three strings, *both* on Intel and AMD visible in cpuinfo: "ibrs", "ibpb" and "stibp" so that there's no confusion what is enabled on each box.
Now, those three can be the *virtual* features which get set by the actual CPUID features on init. And the latter, the *actual* CPUID features don't need to be visible in cpuinfo: people shouldn't care whether "spec_ctrl" on Intel and "pred_cmd" on AMD both mean "ibpb". It should be simply "ibpb" on both vendors in cpuinfo.
Ditto for the others.
This way you have one unified message of what is enabled on *any* box.
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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