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Re: [Xen-devel] [PATCH 02/14] Nested Virtualization: localevent

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 02/14] Nested Virtualization: localevent
From: Christoph Egger <Christoph.Egger@xxxxxxx>
Date: Tue, 10 Aug 2010 10:01:28 +0200
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On Friday 06 August 2010 16:02:11 Keir Fraser wrote:
> On 06/08/2010 10:17, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:
> > For this reason, nestedhvm_vcpu_destroy() (added in patch 5/14)
> > does a nestedsvm_vcpu_stgi() to prevent the interrupts/events
> > from being blocked by hvm_interrupt_blocked() (see patch 9/14)
> > and level 1 guest remaining in a zombie state.
> Ah, this is the crux of it. You shouldn't need to stgi from the vcpu
> destructor. It makes no sense and doing it shouldn't leave you with a
> zombie domain.

I backed out the 'localevent' patch in my local tree, removed the stgi
call in the vcpu destructor and run tests. A lot of things have been
changed since the issue has been found and the real bug might have
already been fixed in the meantime.

I haven't seen any issues with that changes in my tests so my next
patch series I send will have the localevent patch and the stgi call

> Indeed, vcpu_destroy() is called from the very final domain 
> destructor -- vcpu_destroy's caller finishes by freeing the domain
> structure itself, so not much chance of hanging around as a zombie! I'm
> assuming you call nestedhvm_vcpu_destroy() on the vcpu_destroy() path here
> by the way...

Yes, your assumption is correct.

> If it's called from some other context then I think its name 
> is misleading and should be changed.
>  -- Keir


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