linux-kernel - Re: [PATCH v4 2/2] KVM: LAPIC: micro-optimize fixed mode ipi delivery

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Message-ID: <b84594ae-5874-e006-7a9e-dfd30e1bbefd@redhat.com>
Date:   Wed, 15 Jan 2020 18:51:27 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v4 2/2] KVM: LAPIC: micro-optimize fixed mode ipi delivery

On 21/11/19 04:17, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@...cent.com>
> 
> This patch optimizes redundancy logic before fixed mode ipi is delivered
> in the fast path, broadcast handling needs to go slow path, so the delivery
> mode repair can be delayed to before slow path.
> 
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> ---
>  arch/x86/kvm/irq_comm.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
> index 8ecd48d..aa88156 100644
> --- a/arch/x86/kvm/irq_comm.c
> +++ b/arch/x86/kvm/irq_comm.c
> @@ -52,15 +52,15 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
>  	unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)];
>  	unsigned int dest_vcpus = 0;
>  
> +	if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r, dest_map))
> +		return r;
> +
>  	if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
>  			kvm_lowest_prio_delivery(irq)) {
>  		printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
>  		irq->delivery_mode = APIC_DM_FIXED;
>  	}
>  
> -	if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r, dest_map))
> -		return r;
> -
>  	memset(dest_vcpu_bitmap, 0, sizeof(dest_vcpu_bitmap));
>  
>  	kvm_for_each_vcpu(i, vcpu, kvm) {
> 

Applied.

Paolo