linux-kernel - Re: [PATCH v3 09/12] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use

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Message-ID: <01449e47-8c9c-7582-d8e9-783c0933f298@redhat.com>
Date:   Tue, 3 Aug 2021 10:47:25 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Maxim Levitsky <mlevitsk@...hat.com>, kvm@...r.kernel.org
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...en8.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v3 09/12] KVM: x86: hyper-v: Deactivate APICv only when
 AutoEOI feature is in use

On 02/08/21 20:33, Maxim Levitsky wrote:
> Maxim:
>     - always set HV_DEPRECATING_AEOI_RECOMMENDED in kvm_get_hv_cpuid,
>       since this feature can be used regardless of AVIC

I tend to agree here.  While AutoEOI does have a minor performance 
improvement, I suspect that APICv will be available in most cases where 
Windows guest performance matters to that point.

Paolo