From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Kiszka <jan.kiszka@siemens.com>
Subject: Re: [PATCH] KVM: VMX: Fix race between pending IRQ and NMI
Date: Mon, 24 Nov 2008 10:55:27 +0100
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Cc: Jan Kiszka <jan.kiszka@siemens.com>,
	kvm-devel <kvm@vger.kernel.org>,
	"Xu, Jiajun" <jiajun.xu@intel.com>,
	"Yang, Sheng" <sheng.yang@intel.com>
To: Avi Kivity <avi@redhat.com>
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Avi Kivity wrote:
> Jan Kiszka wrote:
>>> But I think I see a bigger issue - if we inject an regular interrupt
>>> while another is pending, then we will encounter this problem.  Looks
>>> like we have to enable the interrupt window after injecting an interrupt
>>> if there are still pending interrupts.
>>>     
>>
>> Yeah, probably. I'm just wondering now if we can set
>> exit-on-interrupt-window while the vcpu state is interruptible (ie.
>> _before_ the injection). There is some entry check like this for NMIs,
>> but maybe no for interrupts. Need to check.
>>   
> 
> Turns out it's not necessary, since the guest eoi will cause an exit and
> allow the code to request an interrupt window.

But you added explicit handling now nevertheless?

> 
> I've added an apic test program so we can track these issues
> (user/test/x86/apic.c).
> 

That's good. BTW, your NMI race fix is still lacking support for the
-no-kvm-irqchip case. Will post an according patch later today.

Jan

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