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Message-ID: <eaefdea0-0ca3-93f1-a815-03900055fdcd@redhat.com>
Date:   Tue, 14 Jun 2022 19:20:34 +0200
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Subject: Re: [PATCH] KVM: nVMX: Don't expose TSC scaling to L1 when on Hyper-V
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To:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Cc:     mail@anirudhrb.com, kumarpraveen@linux.microsoft.com,
        wei.liu@kernel.org, robert.bradford@intel.com, liuwe@microsoft.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Ilias Stamatis <ilstam@amazon.com>,
        Maxim Levitsky <mlevitsk@redhat.com>,
        Sean Christopherson <seanjc@google.com>
References: <20220613161611.3567556-1-anrayabh@linux.microsoft.com>
 <87sfo7igis.fsf@redhat.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <87sfo7igis.fsf@redhat.com>
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On 6/14/22 14:19, Vitaly Kuznetsov wrote:
> The latest version:
> https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/datatypes/hv_vmx_enlightened_vmcs
> 
> has it, actually. It was missing before (compare with e.g. 6.0b version
> here:
> https://github.com/MicrosoftDocs/Virtualization-Documentation/raw/live/tlfs/Hypervisor%20Top%20Level%20Functional%20Specification%20v6.0b.pdf)
> 
> but AFAIR TSC scaling wasn't advertised by genuine Hyper-V either.
> Interestingly enough, eVMCS version didn't change when these fields were
> added, it is still '1'.
> 
> I even have a patch in my stash (attached). I didn't send it out because
> it wasn't properly tested with different Hyper-V versions.
> 
> -- Vitaly

Anirudh, can you check if Vitaly's patches work for you?

Paolo