Re: [PATCH] KVM: x86: Don't deliver PIC interrupts to disabled APICs - v2

[Sheng Yang <yasker@gmail.com>]

On Mon, Oct 20, 2008 at 02:06:13PM +0200, Jan Kiszka wrote:
> [ taking Sheng's comments into account ]
> 
> The logic of kvm_apic_accept_pic_intr has a minor, practically hardly
> relevant incorrectness: PIC interrupts are still delivered even if the
> APIC of VPU0 (BSP) is disabled. This does not comply with the Virtual
> Wire mode according to the Intel MP spec.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Sheng Yang <sheng@linux.intel.com>

--
regards
Yang, Sheng
> ---
>  arch/x86/kvm/lapic.c |   21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> Index: b/arch/x86/kvm/lapic.c
> ===================================================================
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1089,17 +1089,18 @@ int kvm_apic_has_interrupt(struct kvm_vc
>  
>  int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu)
>  {
> -	u32 lvt0 = apic_get_reg(vcpu->arch.apic, APIC_LVT0);
> -	int r = 0;
> +	struct kvm_lapic *apic = vcpu->arch.apic;
> +	u32 lvt0 = apic_get_reg(apic, APIC_LVT0);
>  
> -	if (vcpu->vcpu_id == 0) {
> -		if (!apic_hw_enabled(vcpu->arch.apic))
> -			r = 1;
> -		if ((lvt0 & APIC_LVT_MASKED) == 0 &&
> -		    GET_APIC_DELIVERY_MODE(lvt0) == APIC_MODE_EXTINT)
> -			r = 1;
> -	}
> -	return r;
> +	/*
> +	 * Virtual Wire mode, but we only deliver to the BSP.
> +	 * Note that apic_sw_enabled() is covered by testing for !LVT_MASKED.
> +	 */
> +	if (vcpu->vcpu_id == 0 && apic_hw_enabled(apic)
> +	    && !(lvt0 & APIC_LVT_MASKED)
> +	    && GET_APIC_DELIVERY_MODE(lvt0) == APIC_MODE_EXTINT)
> +		return 1;
> +	return 0;
>  }
>  
>  void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu)
> --
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