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Subject: Re: [PATCH 2/5] KVM: nVMX: Verify the VMX controls MSRs with the
 global capability when setting VMX MSRs
To:     Jim Mattson <jmattson@google.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Joerg Roedel <joro@8bytes.org>,
        Xiaoyao Li <xiaoyao.li@intel.com>,
        kvm list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
References: <20200828085622.8365-1-chenyi.qiang@intel.com>
 <20200828085622.8365-3-chenyi.qiang@intel.com>
 <CALMp9eTDTeKQrCnYsSsMPF3-0N=GW7QPOQY8xg4oiCcmv8hgYA@mail.gmail.com>
From:   Chenyi Qiang <chenyi.qiang@intel.com>
Message-ID: <d80093d9-3368-adc7-050c-75686cd261ec@intel.com>
Date:   Mon, 31 Aug 2020 11:15:50 +0800
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On 8/29/2020 2:23 AM, Jim Mattson wrote:
> On Fri, Aug 28, 2020 at 1:54 AM Chenyi Qiang <chenyi.qiang@intel.com> wrote:
>>
>> When setting the nested VMX MSRs, verify it with the values in
>> vmcs_config.nested_vmx_msrs, which reflects the global capability of
>> VMX controls MSRs.
>>
>> Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
> 
> You seem to have entirely missed the point of this code, which is to
> prevent userspace from adding features that have previously been
> removed for this vCPU (e.g as a side-effect of KVM_SET_CPUID).
> 

We only have the case that the scope of features set by userspace is 
always reduced, right? If so, we don't need the change here.