linux-kernel - Re: [PATCH 07/10] KVM: SVM: use vmcb01 in svm_refresh_apicv_exec

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Message-ID: <bd20da0f-eb20-48f7-3258-cd5949f12227@redhat.com>
Date:   Wed, 23 Jun 2021 23:54:21 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Maxim Levitsky <mlevitsk@...hat.com>, kvm@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH 07/10] KVM: SVM: use vmcb01 in svm_refresh_apicv_exec_ctrl

On 23/06/21 13:29, Maxim Levitsky wrote:
> AVIC is not supported for nesting but in some corner
> cases it is possible to have it still be enabled,
> after we entered nesting, and use vmcb02.
> 
> Fix this by always using vmcb01 in svm_refresh_apicv_exec_ctrl

Please be more verbose about the corner case (and then the second 
paragraph should not be necessary anymore).

Paolo

> Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
> ---
>   arch/x86/kvm/svm/avic.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 1d01da64c333..a8ad78a2faa1 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -646,7 +646,7 @@ static int svm_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate)
>   void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
>   {
>   	struct vcpu_svm *svm = to_svm(vcpu);
> -	struct vmcb *vmcb = svm->vmcb;
> +	struct vmcb *vmcb = svm->vmcb01.ptr;
>   	bool activated = kvm_vcpu_apicv_active(vcpu);
>   
>   	if (!enable_apicv)
>