linux-kernel - Re: [PATCH 4/5] KVM: x86: remove unnecessary sync_pir_to

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Date:   Wed, 26 Oct 2016 22:28:38 +0200
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        yang.zhang.wz@...il.com, feng.wu@...el.com, mst@...hat.com
Subject: Re: [PATCH 4/5] KVM: x86: remove unnecessary sync_pir_to_irr

2016-10-14 20:21+0200, Paolo Bonzini:
> Synchronizing PIR to IRR is not needed in most callers of
> apic_find_highest_irr.  Move it to the one place that matters,
> interrupt acknowledgement.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---

Reviewed-by: Radim Krčmář <rkrcmar@...hat.com>

> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> @@ -1973,6 +1971,9 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu)
>  		return -1;
>  
>  	apic_update_ppr(apic);
> +
> +	if (apic->vcpu->arch.apicv_active)
> +		kvm_x86_ops->sync_pir_to_irr(apic->vcpu);

Btw. do all callers of kvm_apic_has_interrupt() need it?

Thanks.

>  	highest_irr = apic_find_highest_irr(apic);
>  	if ((highest_irr == -1) ||
>  	    ((highest_irr & 0xF0) <= kvm_lapic_get_reg(apic, APIC_PROCPRI)))