linux-kernel - Re: [PATCH 11/19] KVM: SVM: Add helper to perform final AVIC "kick" of single vCPU

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Message-ID: <9144c9921bd46ba7c2b2e9427d053b1fc5abccf7.camel@redhat.com>
Date:   Wed, 31 Aug 2022 13:25:38 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Li RongQing <lirongqing@...du.com>
Subject: Re: [PATCH 11/19] KVM: SVM: Add helper to perform final AVIC "kick"
 of single vCPU

On Wed, 2022-08-31 at 00:34 +0000, Sean Christopherson wrote:
> Add a helper to perform the final kick, two instances of the ICR decoding
> is one too many.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/svm/avic.c | 25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 3959d4766911..2095ece70712 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -329,6 +329,16 @@ void avic_ring_doorbell(struct kvm_vcpu *vcpu)
>  	put_cpu();
>  }
>  
> +
> +static void avic_kick_vcpu(struct kvm_vcpu *vcpu, u32 icrl)
> +{
> +	vcpu->arch.apic->irr_pending = true;
> +	svm_complete_interrupt_delivery(vcpu,
> +					icrl & APIC_MODE_MASK,
> +					icrl & APIC_INT_LEVELTRIG,
> +					icrl & APIC_VECTOR_MASK);
> +}
> +
>  /*
>   * A fast-path version of avic_kick_target_vcpus(), which attempts to match
>   * destination APIC ID to vCPU without looping through all vCPUs.
> @@ -427,11 +437,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
>  	if (unlikely(!target_vcpu))
>  		return 0;
>  
> -	target_vcpu->arch.apic->irr_pending = true;
> -	svm_complete_interrupt_delivery(target_vcpu,
> -					icrl & APIC_MODE_MASK,
> -					icrl & APIC_INT_LEVELTRIG,
> -					icrl & APIC_VECTOR_MASK);
> +	avic_kick_vcpu(target_vcpu, icrl);
>  	return 0;
>  }
>  
> @@ -455,13 +461,8 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
>  	 */
>  	kvm_for_each_vcpu(i, vcpu, kvm) {
>  		if (kvm_apic_match_dest(vcpu, source, icrl & APIC_SHORT_MASK,
> -					dest, icrl & APIC_DEST_MASK)) {
> -			vcpu->arch.apic->irr_pending = true;
> -			svm_complete_interrupt_delivery(vcpu,
> -							icrl & APIC_MODE_MASK,
> -							icrl & APIC_INT_LEVELTRIG,
> -							icrl & APIC_VECTOR_MASK);
> -		}
> +					dest, icrl & APIC_DEST_MASK))
> +			avic_kick_vcpu(vcpu, icrl);
>  	}
>  }
>  

I don't know what I think about this, sometimes *minor* code duplication might actually
be a good thing, as it is easier to read the code, but I don't have much against this
as well.

I am not sure if before or after this code is more readable.

But anyway,

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky