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Re: [Xen-devel] Configuration of nestedhvm

To: "Dong, Eddie" <eddie.dong@xxxxxxxxx>
Subject: Re: [Xen-devel] Configuration of nestedhvm
From: Keir Fraser <keir@xxxxxxx>
Date: Fri, 08 Oct 2010 09:22:44 +0100
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] Configuration of nestedhvm
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On 08/10/2010 08:56, "Dong, Eddie" <eddie.dong@xxxxxxxxx> wrote:

>> What's the point when a per-domain config option is going to be
>> implemented? You can then simply not configure nestedhvm for a domain
>> you want to test without that capability? I suppose it makes your
>> second patch make a bit more sense than it would in total isolation.
> I want double-lock (AND) like other components such as IOMMU.
> If the global switch is off, even per domain configuration is turned on, the
> final effect is "OFF".
> The point here is to avoid manual mistake when the nested code is built in as
> formal release but targeting for pilot. Relying on HVM guest configuration
> only may cause the host crash or performance impact if the code has a bug and
> a guest enables nested virtualization feature.
> This switch is mainly for developer only at least for now.

Well, at least it should only be disallowing toolstack to set the per-domain
config option. Then it won't need to be accessed on every use of
is_nestedhvm(). So again it depends on that, mainly tool-side, patch.

 -- Keir

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