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Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls

From Paolo Bonzini <pbonzini@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls
Date 2017-08-24 18:10 +0200
Message-ID <ui2RI-kG-25@gated-at.bofh.it> (permalink)
References (2 earlier) <ui1Ch-7QZ-5@gated-at.bofh.it> <ui2f0-8jI-5@gated-at.bofh.it> <ui2yl-8q8-9@gated-at.bofh.it> <ui2ym-8q8-25@gated-at.bofh.it> <ui2RI-kG-27@gated-at.bofh.it>
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On 24/08/2017 18:02, Jim Mattson wrote:
> On the subject of complexity, why do we clear
> CPUID.(EAX=07H,ECX=0):EBX.INVPCID[bit 10] when CPUID.01H:ECX.PCID[bit
> 17] is clear? Sure, it would be odd to support the INVPCID instruction
> without also supporting PCIDs, but why single out this one check?
> Isn't it equally bizarre to support SSE2 without SSE, or XSAVES
> without XSAVE, or RDTSCP without TSC, or DS-CPL without DS, or ...?

I actually agree with you.  It's just been like this forever:

    commit ad756a1603c5fac207758faaac7f01c34c9d0b7b
    Author: Mao, Junjie <junjie.mao@intel.com>
    Date:   Mon Jul 2 01:18:48 2012 +0000

    KVM: VMX: Implement PCID/INVPCID for guests with EPT

Paolo

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[PATCH v7 0/4] Raise #UD and disable execution controls for more CPUID bits Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 15:40 +0200
  [PATCH 3/4] kvm: vmx: Raise #UD on unsupported RDSEED Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 15:40 +0200
    Re: [PATCH 3/4] kvm: vmx: Raise #UD on unsupported RDSEED David Hildenbrand <david@redhat.com> - 2017-08-24 19:50 +0200
  [PATCH 1/4] KVM: VMX: cache secondary exec controls Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 15:40 +0200
    Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls Jim Mattson <jmattson@google.com> - 2017-08-24 16:50 +0200
      Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 17:30 +0200
        Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls Jim Mattson <jmattson@google.com> - 2017-08-24 17:50 +0200
          Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 17:50 +0200
            Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 18:10 +0200
            Re: [PATCH 1/4] KVM: VMX: cache secondary exec controls Jim Mattson <jmattson@google.com> - 2017-08-24 18:10 +0200
  [PATCH 2/4] kvm: vmx: Raise #UD on unsupported RDRAND Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 15:40 +0200
    Re: [PATCH 2/4] kvm: vmx: Raise #UD on unsupported RDRAND David Hildenbrand <david@redhat.com> - 2017-08-24 19:50 +0200
  [PATCH 4/4] kvm: vmx: Raise #UD on unsupported XSAVES/XRSTORS Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 15:40 +0200
    Re: [PATCH 4/4] kvm: vmx: Raise #UD on unsupported XSAVES/XRSTORS Jim Mattson <jmattson@google.com> - 2017-08-24 17:00 +0200
      [PATCH v8 4/4] kvm: vmx: Raise #UD on unsupported XSAVES/XRSTORS Paolo Bonzini <pbonzini@redhat.com> - 2017-08-24 18:20 +0200
        Re: [PATCH v8 4/4] kvm: vmx: Raise #UD on unsupported XSAVES/XRSTORS Jim Mattson <jmattson@google.com> - 2017-08-24 22:50 +0200

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