From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH] kernel/kvm: fix improper nmi emulation
Date: Mon, 10 Oct 2011 12:26:53 +0200
Message-ID: <4E92C86D.9000701@redhat.com>
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Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>, seabios@seabios.org,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Jan Kiszka <jan.kiszka@web.de>,
	Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
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On 10/10/2011 08:06 AM, Lai Jiangshan wrote:
> From: Kenji Kaneshige<kaneshige.kenji@jp.fujitsu.com>
>
> Currently, NMI interrupt is blindly sent to all the vCPUs when NMI
> button event happens. This doesn't properly emulate real hardware on
> which NMI button event triggers LINT1. Because of this, NMI is sent to
> the processor even when LINT1 is maskied in LVT. For example, this
> causes the problem that kdump initiated by NMI sometimes doesn't work
> on KVM, because kdump assumes NMI is masked on CPUs other than CPU0.
>
> With this patch, KVM_NMI ioctl is handled as follows.
>
> - When in-kernel irqchip is enabled, KVM_NMI ioctl is handled as a
>    request of triggering LINT1 on the processor. LINT1 is emulated in
>    in-kernel irqchip.
>
> - When in-kernel irqchip is disabled, KVM_NMI ioctl is handled as a
>    request of injecting NMI to the processor. This assumes LINT1 is
>    already emulated in userland.

Please add a KVM_NMI section to Documentation/virtual/kvm/api.txt.

>
> -static int kvm_vcpu_ioctl_nmi(struct kvm_vcpu *vcpu)
> -{
> -	kvm_inject_nmi(vcpu);
> -
> -	return 0;
> -}
> -
>   static int vcpu_ioctl_tpr_access_reporting(struct kvm_vcpu *vcpu,
>   					   struct kvm_tpr_access_ctl *tac)
>   {
> @@ -3038,9 +3031,10 @@ long kvm_arch_vcpu_ioctl(struct file *fi
>   		break;
>   	}
>   	case KVM_NMI: {
> -		r = kvm_vcpu_ioctl_nmi(vcpu);
> -		if (r)
> -			goto out;
> +		if (irqchip_in_kernel(vcpu->kvm))
> +			kvm_apic_lint1_deliver(vcpu);
> +		else
> +			kvm_inject_nmi(vcpu);
>   		r = 0;
>   		break;
>   	}

Why did you drop kvm_vcpu_ioctl_nmi()?

Please add (and document) a KVM_CAP flag that lets userspace know the 
new behaviour is supported.

-- 
error compiling committee.c: too many arguments to function