From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joerg Roedel <joro@8bytes.org>
Subject: Re: Nested SVM and migration
Date: Sun, 21 Feb 2010 14:09:15 +0100
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References: <4B80347E.7000003@redhat.com> <20100220201822.GG20833@8bytes.org> <4B806FB9.20009@redhat.com> <20100221121008.GI20833@8bytes.org> <4B8125E2.8050309@redhat.com> <20100221124141.GA26465@8bytes.org> <4B812CE9.2070107@redhat.com>
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Cc: Zachary Amsden <zamsden@redhat.com>,
	Joerg Roedel <joerg.roedel@amd.com>, kvm <kvm@vger.kernel.org>
To: Avi Kivity <avi@redhat.com>
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On Sun, Feb 21, 2010 at 02:54:01PM +0200, Avi Kivity wrote:
> So, if some other cpu (or the guest itself, with appropriate  
> permissions) modifies the msr permission bitmap, svm will not notice  
> this?  svm loads the bitmap during entry?

Yes.

> I don't think you can tell, unless the host cpu modifying the vmcb is  
> synchronized with the guest (or the guest modifies its own vmcb).  But  
> this is all academic.

Hmm, another thing comes to mind. We would need some redesign of the
nested_svm code to allow userspace to put a vcpu directly into nested
state. With the MSR approach, all userspace does is to write MSRs into
the vcpu before the first run?

	Joerg