Messages in this thread | | | Date | Mon, 6 Mar 2023 22:47:18 +0100 | Subject | Re: [PATCH 0/2] KVM: x86: Propagate AMD-specific IBRS bits to guests | From | Paolo Bonzini <> |
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On 3/6/23 22:44, Borislav Petkov wrote: >> I thought that the consensus was that adding unused-by-the-kernel flags to >> cpufeatures.h is ok so long as the feature is hidden from /proc/cpuinfo and the >> kernel already dedicates a word to the CPUID leaf? > I guess we should finally write it down in Documentation/x86/cpuinfo.rst > > And in case there's no dedicated word, it should be resorted to KVM-only > feature flags. > > In any case, I'd like for baremetal CPUID stuff to be decoupled from > KVM's machinery as far as possible as both have different goals wrt > feature flags.
It's very rare that KVM can provide a CPUID feature if the kernel has masked it, so if the kernel needs to know about a feature word than KVM most likely needs to know what kind of massaging the kernel has done.
Paolo
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