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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Wanpeng Li <kernellwp@gmail.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        "Paul K ." <kronenpj@kronenpj.dyndns.org>
Subject: Re: [PATCH 3/3] KVM: SVM: Reenable handle_fastpath_set_msr_irqoff() after complete_interrupts()
In-Reply-To: <1599620139-13019-1-git-send-email-wanpengli@tencent.com>
References: <1599620139-13019-1-git-send-email-wanpengli@tencent.com>
Date:   Wed, 09 Sep 2020 10:41:48 +0200
Message-ID: <87blifmjeb.fsf@vitty.brq.redhat.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Wanpeng Li <kernellwp@gmail.com> writes:

> From: Wanpeng Li <wanpengli@tencent.com>
>
> Moving the call to svm_exit_handlers_fastpath() after svm_complete_interrupts() 
> since svm_complete_interrupts() consumes rip and reenable the function 
> handle_fastpath_set_msr_irqoff() call in svm_exit_handlers_fastpath().
>
> Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Paul K. <kronenpj@kronenpj.dyndns.org>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
>  arch/x86/kvm/svm/svm.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 74bcf0a..ac819f0 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3347,6 +3347,11 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu)
>  
>  static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
>  {
> +	if (!is_guest_mode(vcpu) &&
> +	    to_svm(vcpu)->vmcb->control.exit_code == SVM_EXIT_MSR &&
> +	    to_svm(vcpu)->vmcb->control.exit_info_1)
> +		return handle_fastpath_set_msr_irqoff(vcpu);
> +
>  	return EXIT_FASTPATH_NONE;
>  }
>  
> @@ -3495,7 +3500,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
>  	stgi();
>  
>  	/* Any pending NMI will happen here */
> -	exit_fastpath = svm_exit_handlers_fastpath(vcpu);
>  
>  	if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
>  		kvm_after_interrupt(&svm->vcpu);
> @@ -3529,6 +3533,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
>  		svm_handle_mce(svm);
>  
>  	svm_complete_interrupts(svm);
> +	exit_fastpath = svm_exit_handlers_fastpath(vcpu);
>  
>  	vmcb_mark_all_clean(svm->vmcb);
>  	return exit_fastpath;

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

-- 
Vitaly