linux-kernel - Re: [PATCH 2/5] KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap support for real

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Message-ID: <efc05e35-b37f-5d9b-d00e-f4f2edc0441b@redhat.com>
Date:   Tue, 25 Jan 2022 16:53:22 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap
 support for real

On 12/20/21 16:21, Vitaly Kuznetsov wrote:
> Commit c4327f15dfc7 ("KVM: SVM: hyper-v: Enlightened MSR-Bitmap support")
> introduced enlightened MSR-Bitmap support for KVM-on-Hyper-V but it didn't
> actually enable the support. Similar to enlightened NPT TLB flush and
> direct TLB flush features, the guest (KVM) has to tell L0 (Hyper-V) that
> it's using the feature by setting the appropriate feature fit in VMCB
> control area (sw reserved fields).
> 
> Fixes: c4327f15dfc7 ("KVM: SVM: hyper-v: Enlightened MSR-Bitmap support")
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>   arch/x86/kvm/svm/svm_onhyperv.h | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm/svm_onhyperv.h b/arch/x86/kvm/svm/svm_onhyperv.h
> index cdbcfc63d171..489ca56212c6 100644
> --- a/arch/x86/kvm/svm/svm_onhyperv.h
> +++ b/arch/x86/kvm/svm/svm_onhyperv.h
> @@ -46,6 +46,9 @@ static inline void svm_hv_init_vmcb(struct vmcb *vmcb)
>   	if (npt_enabled &&
>   	    ms_hyperv.nested_features & HV_X64_NESTED_ENLIGHTENED_TLB)
>   		hve->hv_enlightenments_control.enlightened_npt_tlb = 1;
> +
> +	if (ms_hyperv.nested_features & HV_X64_NESTED_MSR_BITMAP)
> +		hve->hv_enlightenments_control.msr_bitmap = 1;
>   }
>   
>   static inline void svm_hv_hardware_setup(void)

Queued this one for now.

Paolo