Groups > linux.kernel > #1719370

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

From	Jim Mattson <jmattson@google.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-27@gated-at.bofh.it> (permalink)
References	(1 earlier) <ui0wz-7c2-29@gated-at.bofh.it> <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>
Organization	linux.* mail to news gateway

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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 ...?

On Thu, Aug 24, 2017 at 8:46 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 24/08/2017 17:41, Jim Mattson wrote:
>> Userspace can establish the value of the virtualized
>> IA32_VMX_PROCBASED_CTLS2 MSR via the KVM_SET_MSRS ioctl, which goes
>> through vms_set_vmx_msr. But maybe that's not important, since
>> features can only be disabled on that path.
>
> Yeah, I was only thinking of non-nested in the commit message.  It's
> complicated enough. :)
>
> Paolo
>
>> On Thu, Aug 24, 2017 at 8:25 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>> On 24/08/2017 16:47, Jim Mattson wrote:
>>>>> Currently, secondary execution controls are divided in three groups:
>>>>>
>>>>> - static, depending mostly on the module arguments or the processor
>>>>>   (vmx_secondary_exec_control)
>>>>>
>>>>> - static, depending on CPUID (vmx_cpuid_update)
>>>> There should also be:
>>>>
>>>> - static, depending on guest VMX capability MSRs (vmx_set_vmx_msr)
>>> Can you explain what you mean?
>>>
>>> Paolo
>

Thread

[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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