linux-kernel - Re: [PATCH 1/9] KVM: SVM: Notify nested hypervisor of lost event injections

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Date:	Thu, 8 Oct 2009 18:46:48 +0200
From:	Alexander Graf <agraf@...e.de>
To:	Avi Kivity <avi@...hat.com>
Cc:	Joerg Roedel <joerg.roedel@....com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/9] KVM: SVM: Notify nested hypervisor of lost event injections



Am 08.10.2009 um 18:38 schrieb Avi Kivity <avi@...hat.com>:

> On 10/08/2009 06:32 PM, Joerg Roedel wrote:
>> No. The L1 guest needs to execute VMRUN with an interrupt to inject  
>> to
>> the L2 guest with event_inj. On that VMRUN instruction emulation an
>> interrupt becomes pending which causes an immediate #vmexit from L2  
>> to
>> L2 again without even entering the L2 guest. The bug was that in this
>> case the event which the L1 tried to inject in the L2 was lost  
>> because
>> it was not copied to exit_int_info.
>>
>
> (from L1 to L0?)
>
> Wow.  Alex, how did you find this?

Hyper-V got stuck and I was trying to think of possible reasons  
looking at the logs :-).
Fortunately this patch also seemed to make things work better with KVM  
in KVM.

Doesn't really help with regression testing though...

Alex

>
> We can try to cause an interrupt using a signal from another thread,  
> but that's too difficult as the first test in a test suite.
>
> -- 
> error compiling committee.c: too many arguments to function
>
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