Re: [PATCH v3 1/4] KVM: Recover IRTE to remapped mode if the interrupt is not single-destination

[Radim Krčmář]

2016-01-20 09:42+0800, Feng Wu:
> When the interrupt is not single destination any more, we need
> to change back IRTE to remapped mode explicitly.
> 
> Signed-off-by: Feng Wu <feng...@intel.com>
> ---
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> @@ -10764,8 +10764,17 @@ static int vmx_update_pi_irte(struct kvm *kvm, 
> unsigned int host_irq,
> -             if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu))
> +             if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) {
> +                     /*
> +                      * Make sure the IRTE is in remapped mode if
> +                      * we don't handle it in posted mode.
> +                      */
> +                     pi_set_sn(vcpu_to_pi_desc(vcpu));

What could go wrong if we didn't suppress notifications here?

Thanks.

> +                     ret = irq_set_vcpu_affinity(host_irq, NULL);
> +                     pi_clear_sn(vcpu_to_pi_desc(vcpu));
> +
>                       continue;
> +             }