From: Omar Khan <okhan-e94Sedi4moU@public.gmane.org>
To: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: paravirtualization structure
Date: Tue, 20 Feb 2007 00:47:34 +0000 (UTC) [thread overview]
Message-ID: <loom.20070220T011441-39@post.gmane.org> (raw)
In-Reply-To: 64F9B87B6B770947A9F8391472E032160A8186EE@ehost011-8.exch011.intermedia.net
Dor Laor <dor.laor@...> writes:
>
> Theoretically speaking the answer is yes, vmcall is a special
> instruction that it one and only purpose is the exit from the guest.
> While mov cr3 instruction might be bound to other actions of the
> processor and might have more effects on the pipeline, this harder to
> optimize for vmexit purposes.
>
I guess what is confusing me is that the vmcall causes an vmexit in VMX non-root
mode (the one in which a paravirtualized guest is operating), but Avi says that
a hypercal (made using a vmcall) 'avoids' a vmentry/vmexit and Ingo comments in
his patch that :
"This utilizes the cr3 filter capability of the hardware - if this works out
then no VM exit happens"
NO VM-exits happen. hmmmm... maybe I need to go over the intel manuals more
thoroughly, however any hints will be most welcomed.
Thanks
Omar
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next prev parent reply other threads:[~2007-02-20 0:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-19 15:17 paravirtualization structure Omar Khan
[not found] ` <loom.20070219T155153-393-eS7Uydv5nfjZ+VzJOa5vwg@public.gmane.org>
2007-02-19 15:24 ` Avi Kivity
2007-02-19 20:29 ` Omar Khan
[not found] ` <loom.20070219T211655-267-eS7Uydv5nfjZ+VzJOa5vwg@public.gmane.org>
2007-02-19 21:18 ` Dor Laor
2007-02-20 0:47 ` Omar Khan [this message]
[not found] ` <loom.20070220T011441-39-eS7Uydv5nfjZ+VzJOa5vwg@public.gmane.org>
2007-02-20 7:14 ` Avi Kivity
2007-02-20 8:18 ` Arjan van de Ven
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