From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Alvin Starr <alvin@netvel.net>
Cc: xen-devel@lists.xen.org
Subject: Re: libvirt and nestedhvm.
Date: Fri, 6 Jun 2014 14:33:54 +0100 [thread overview]
Message-ID: <5391C342.3090800@citrix.com> (raw)
In-Reply-To: <5391C1F3.9040603@netvel.net>
On 06/06/14 14:28, Alvin Starr wrote:
> I am trying to shoehorn the ability to start a nested HVM into libvirt
> through the libxl interface.
>
> Setting the nestedhvm flag is easy enough but I also need to mask the
> svm_npt cpuid flags.
This presumably comes from a KVM centric view where the environment
running libvirtd is the host environment?
>
> This is where life gets interesting.
>
> LIbvirt seems to probe the CPUID registers to determine what flags are
> available.
> Libvirt then stops me from trying to mask the svm or npt flags since
> they are not visible in dom0.
>
> So my question is.
> Can I enable the svm,npt flags in dom0?
Technically it is possible to make these flags appear...
> Is there anything equivalent to nestedhvm for dom0?
... but being features that PV guests cannot possibly use, advertising
them is a bad idea.
>
> or is there a way to read the raw CPU flags?
>
Not really.
It is one of the many things on my bucketlist of basic things which need
fixing with all the other Xen/libxc/toolstack cpuid work.
~Andrew
prev parent reply other threads:[~2014-06-06 13:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-06 13:28 libvirt and nestedhvm Alvin Starr
2014-06-06 13:33 ` Andrew Cooper [this message]
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