Re: [PATCH v8 12/13] KVM: Warn if 'SN' is set during posting interrupts by software

From: Paolo Bonzini <pbonzini@redhat.com>
To: Feng Wu <feng.wu@intel.com>,
	alex.williamson@redhat.com, joro@8bytes.org, mtosatti@redhat.com
Cc: eric.auger@linaro.org, kvm@vger.kernel.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 12/13] KVM: Warn if 'SN' is set during posting interrupts by software
Date: Wed, 16 Sep 2015 11:32:35 +0200	[thread overview]
Message-ID: <55F93733.2010403@redhat.com> (raw)
In-Reply-To: <1442393409-2623-13-git-send-email-feng.wu@intel.com>

On 16/09/2015 10:50, Feng Wu wrote:
> Currently, we don't support urgent interrupt, all interrupts
> are recognized as non-urgent interrupt, so we cannot post
> interrupts when 'SN' is set.
> 
> If the vcpu is in guest mode, it cannot have been scheduled out,
> and that's the only case when SN is set currently, warning if
> SN is set.
> 
> Signed-off-by: Feng Wu <feng.wu@intel.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Please fold this into patch 10.

Paolo

> ---
>  arch/x86/kvm/vmx.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9888c43..58fbbc6 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -4498,6 +4498,22 @@ static inline bool kvm_vcpu_trigger_posted_interrupt(struct kvm_vcpu *vcpu)
>  {
>  #ifdef CONFIG_SMP
>  	if (vcpu->mode == IN_GUEST_MODE) {
> +		struct vcpu_vmx *vmx = to_vmx(vcpu);
> +
> +		/*
> +		 * Currently, we don't support urgent interrupt,
> +		 * all interrupts are recognized as non-urgent
> +		 * interrupt, so we cannot post interrupts when
> +		 * 'SN' is set.
> +		 *
> +		 * If the vcpu is in guest mode, it means it is
> +		 * running instead of being scheduled out and
> +		 * waiting in the run queue, and that's the only
> +		 * case when 'SN' is set currently, warning if
> +		 * 'SN' is set.
> +		 */
> +		WARN_ON_ONCE(pi_test_sn(&vmx->pi_desc));
> +
>  		apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
>  				POSTED_INTR_VECTOR);
>  		return true;
> 