linux-kernel - Re: [PATCH 2/5] KVM: nVMX: Verify the VMX controls MSRs with the global capability when setting VMX MSRs

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Message-ID: <CALMp9eTDTeKQrCnYsSsMPF3-0N=GW7QPOQY8xg4oiCcmv8hgYA@mail.gmail.com>
Date:   Fri, 28 Aug 2020 11:23:43 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Chenyi Qiang <chenyi.qiang@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] KVM: nVMX: Verify the VMX controls MSRs with the
 global capability when setting VMX MSRs

On Fri, Aug 28, 2020 at 1:54 AM Chenyi Qiang <chenyi.qiang@...el.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@...el.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).