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Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS features to kvm guest

From Paolo Bonzini <pbonzini@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS features to kvm guest
Date 2016-10-31 11:50 +0100
Message-ID <syika-1bP-5@gated-at.bofh.it> (permalink)
References (6 earlier) <sxAVP-6bh-7@gated-at.bofh.it> <sygV3-nL-7@gated-at.bofh.it> <syhxM-Bp-25@gated-at.bofh.it> <syhR8-110-23@gated-at.bofh.it> <syiat-17S-7@gated-at.bofh.it>
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On 31/10/2016 11:30, Borislav Petkov wrote:
> On Mon, Oct 31, 2016 at 10:18:41AM +0000, Luc, Piotr wrote:
>> The cpuid_mask function, which usually used in kvm, read bit from this
>> x86_capabity and mask out. This prevents passing disabled features to
>> guest. If we use cpu_count instead, which reports bits directly from
> 
> Ah, you mean cpuid_count().
> 
>> CPU, then the bits of features that are disabled in host are passed to
>> guest as enabled. This seems be inconsistent.
> 
> Ok, I see what you mean.
> 
> So I guess we'll have to iterate over the cpuid_bits[] array and
> recreate the CPUID leaf for KVM instead, as I suggested earlier.

Yes, indeed. :(

The information is all in arch/x86/kernel/cpu/scattered.c's cpuid_bits
array.  Borislav, would it be okay to export the cpuid_regs enum?

Paolo

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Thread

[PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS features to kvm guest He Chen <he.chen@linux.intel.com> - 2016-10-28 11:20 +0200
  Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-28 11:40 +0200
    Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest He Chen <he.chen@linux.intel.com> - 2016-10-28 11:50 +0200
      Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest He Chen <he.chen@linux.intel.com> - 2016-10-28 12:00 +0200
      Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-28 12:00 +0200
  Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest "Luc, Piotr" <Piotr.Luc@intel.com> - 2016-10-28 12:20 +0200
    Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-28 12:20 +0200
      Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-10-28 13:10 +0200
        Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-28 14:10 +0200
          Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-10-28 14:30 +0200
            Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-10-29 14:30 +0200
              Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-29 14:50 +0200
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-10-29 15:00 +0200
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-29 15:30 +0200
            Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-29 14:30 +0200
              Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest "Luc, Piotr" <Piotr.Luc@intel.com> - 2016-10-31 10:20 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-10-31 11:00 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest "Luc, Piotr" <Piotr.Luc@intel.com> - 2016-10-31 11:20 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-10-31 11:40 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-31 11:50 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-10-31 12:10 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Paolo Bonzini <pbonzini@redhat.com> - 2016-10-31 12:50 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest He Chen <he.chen@linux.intel.com> - 2016-11-01 08:50 +0100
                Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS  features to kvm guest Borislav Petkov <bp@alien8.de> - 2016-11-01 09:50 +0100

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