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From:   Jim Mattson <jmattson@google.com>
Date:   Wed, 29 Jun 2022 15:27:32 -0700
Message-ID: <CALMp9eQ5Sqv3RP8kipSbpfnvef_Sc1xr1+g53fwr0a=bhzgAhg@mail.gmail.com>
Subject: Re: [PATCH 00/14] KVM: nVMX: Use vmcs_config for setting up nested
 VMX MSRs
To:     Vitaly Kuznetsov <vkuznets@redhat.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Anirudh Rayabharam <anrayabh@linux.microsoft.com>,
        kvm@vger.kernel.org, Wanpeng Li <wanpengli@tencent.com>,
        Maxim Levitsky <mlevitsk@redhat.com>,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org
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On Wed, Jun 29, 2022 at 2:06 AM Vitaly Kuznetsov <vkuznets@redhat.com> wrote:

> For PERF_GLOBAL_CTRL errata:
> - We can move the filtering to vmx_vmexit_ctrl()/vmx_vmentry_ctrl()
> preserving the status quo: KVM doesn't use the feature but it is exposed
> to L1 hypervisor (and L1 hypervisor presumably has the same check and
> doesn't use the feature. FWIW, the workaround was added in 2011 and the
> erratas it references appeared in 2010, this means that the affected
> CPUs are quite old, modern proprietary hypervisors won't likely boot
> there).
Sadly, Nehalem and Westmere are well-supported by KVM today, and we
will probably still continue to support them for at least another
decade. They both have EPT, unrestricted guest, and other VT-x2
features that KVM still considers optional.