linux-kernel - Re: [PATCH 00/14] KVM: nVMX: Use vmcs_config for setting up nested VMX MSRs

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

On Wed, Jun 29, 2022 at 2:06 AM Vitaly Kuznetsov <vkuznets@...hat.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.