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Re: [Xen-devel] [PATCH] nestedhvm: ASID emulation

To: Christoph Egger <Christoph.Egger@xxxxxxx>
Subject: Re: [Xen-devel] [PATCH] nestedhvm: ASID emulation
From: Keir Fraser <keir@xxxxxxx>
Date: Thu, 14 Apr 2011 15:43:55 +0100
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Thread-topic: [Xen-devel] [PATCH] nestedhvm: ASID emulation
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On 14/04/2011 15:01, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:

>> What if some other vcpu's nv_n1asid or nv_n2asid got assigned the same HW
>> asid in this generation as this vcpu's (now stale, as it's from a previous
>> generation's) nv_n2asid? This PCPU can be interleaving execution of other
>> HVM VCPUs after all.
> I am not sure if I got you right. You mean what if two vcpus run on one
> physical cpu? In this case svm_do_resume() calls hvm_asid_flush_vcpu()
> before so that asid_generation and core_asid_generation do not match and
> a new asid is always assigned.

No, it only does that if a given VCPU gets scheduled onto a *different* PCPU
than last time it ran.

I've attached a mostly rewritten version of your patch that is about half
the size and I believe has a fighting chance of being correct (however it is
only build tested). Give it a look and a spin.

 -- Keir

> Christoph

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