linux-kernel - Re: [PATCH v4 09/25] KVM: VMX: nVMX: Support TSC scaling and PERF_GLOBAL

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Message-ID: <87les623x4.fsf@redhat.com>
Date:   Tue, 02 Aug 2022 15:03:35 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org,
        Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 09/25] KVM: VMX: nVMX: Support TSC scaling and
 PERF_GLOBAL_CTRL with enlightened VMCS

Paolo Bonzini <pbonzini@...hat.com> writes:

> On 7/29/22 00:13, Sean Christopherson wrote:
>> The only flaw in this is if KVM gets handed a CPUID model that enumerates support
>> for 2025 (or whenever the next update comes) but not 2022.  Hmm, though if Microsoft
>> defines each new "version" as a full superset, then even that theoretical bug goes
>> away.  I'm happy to be optimistic for once and give this a shot.  I definitely like
>> that it makes it easier to see the deltas between versions.
>
> Okay, I have queued the series but I still haven't gone through all the 
> comments.

The biggest problem with this version is the EFER.LMA problem on i386
discovered (and, thankfully, fixed in the suggested patch) by
Sean. To address this and all other comment I'm going to put together a
v5 on top of the current kvm/queue (as I don't yet see any of this stuff
there).

>  So this will _not_ be in the 5.21 pull request.

At first I thought you meant 5.20 but then I got the pun: 5.20 will
likely become 6.0 and so 5.21 pull request will just never happen :-)

-- 
Vitaly