linux-kernel - Re: [PATCH v1 09/11] KVM: x86: reset lapic base in kvm_lapic

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Message-ID: <137055b6-436e-ee22-e3c2-6e0c06cf4a88@redhat.com>
Date:	Fri, 1 Jul 2016 10:43:10 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Radim Krčmář <rkrcmar@...hat.com>,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:	"Lan, Tianyu" <tianyu.lan@...el.com>,
	Igor Mammedov <imammedo@...hat.com>,
	Jan Kiszka <jan.kiszka@....de>, Peter Xu <peterx@...hat.com>
Subject: Re: [PATCH v1 09/11] KVM: x86: reset lapic base in kvm_lapic_reset



On 30/06/2016 22:54, Radim Krčmář wrote:
> LAPIC is reset in xAPIC mode and the surrounding code expects that.
> KVM never resets after initialization.  This patch is just for sanity.
> 
> Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
> ---
>  arch/x86/kvm/lapic.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 143df33f451e..46eb71c425cf 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1758,8 +1758,11 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
>  	/* Stop the timer in case it's a reset to an active apic */
>  	hrtimer_cancel(&apic->lapic_timer.timer);
>  
> -	if (!init_event)
> +	if (!init_event) {
> +		kvm_lapic_set_base(vcpu, APIC_DEFAULT_PHYS_BASE |
> +		                         MSR_IA32_APICBASE_ENABLE);
>  		kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
> +	}
>  	kvm_apic_set_version(apic->vcpu);
>  
>  	for (i = 0; i < KVM_APIC_LVT_NUM; i++)
> @@ -1898,9 +1901,6 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu)
>  	 * thinking that APIC satet has changed.
>  	 */
>  	vcpu->arch.apic_base = MSR_IA32_APICBASE_ENABLE;
> -	kvm_lapic_set_base(vcpu,
> -			APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE);
> -
>  	static_key_slow_inc(&apic_sw_disabled.key); /* sw disabled at reset */
>  	kvm_lapic_reset(vcpu, false);
>  	kvm_iodevice_init(&apic->dev, &apic_mmio_ops);
> 

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>