linux-kernel - Re: [PATCH 09/10] KVM: VMX: Cache vmx->exit_reason in local u16 in vmx_handle_exit

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Message-ID: <87h7ysny6s.fsf@vitty.brq.redhat.com>
Date:   Fri, 13 Mar 2020 15:09:47 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>
Subject: Re: [PATCH 09/10] KVM: VMX: Cache vmx->exit_reason in local u16 in vmx_handle_exit_irqoff()

Sean Christopherson <sean.j.christopherson@...el.com> writes:

> Use a u16 to hold the exit reason in vmx_handle_exit_irqoff(), as the
> checks for INTR/NMI/WRMSR expect to encounter only the basic exit reason
> in vmx->exit_reason.
>

True Sean would also add:

"No functional change intended."

"Opportunistically align the params to handle_external_interrupt_irqoff()."

> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/vmx/vmx.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d43e1d28bb58..910a7cadeaf7 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6287,16 +6287,16 @@ static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
>  STACK_FRAME_NON_STANDARD(handle_external_interrupt_irqoff);
>  
>  static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu,
> -	enum exit_fastpath_completion *exit_fastpath)
> +				   enum exit_fastpath_completion *exit_fastpath)
>  {
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
> +	u16 exit_reason = vmx->exit_reason;
>  
> -	if (vmx->exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
> +	if (exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
>  		handle_external_interrupt_irqoff(vcpu);
> -	else if (vmx->exit_reason == EXIT_REASON_EXCEPTION_NMI)
> +	else if (exit_reason == EXIT_REASON_EXCEPTION_NMI)
>  		handle_exception_nmi_irqoff(vmx);
> -	else if (!is_guest_mode(vcpu) &&
> -		vmx->exit_reason == EXIT_REASON_MSR_WRITE)
> +	else if (!is_guest_mode(vcpu) && exit_reason == EXIT_REASON_MSR_WRITE)
>  		*exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
>  }

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

-- 
Vitaly