From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH 10/11] KVM: nVMX: Synchronize VMCS12 content with the
 shadow vmcs
Date: Sun, 14 Apr 2013 13:07:10 +0300
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Cc: dongxiao.xu@intel.com, jun.nakajima@intel.com, kvm@vger.kernel.org,
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	"Nadav Har'El" <nyh@math.technion.ac.il>, owasserm@redhat.com
To: Abel Gordon <ABELG@il.ibm.com>
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On Sun, Apr 14, 2013 at 01:00:10PM +0300, Gleb Natapov wrote:
> On Sun, Apr 14, 2013 at 12:51:34PM +0300, Abel Gordon wrote:
> > 
> > 
> > Gleb Natapov <gleb@redhat.com> wrote on 12/04/2013 01:48:04 PM:
> > 
> > > On Fri, Apr 12, 2013 at 01:44:14PM +0300, Abel Gordon wrote:
> > > >
> > > > Ok, so then you prefer to add the inline functions to read/write to the
> > > > vmcs12
> > > > fields, (to set the request bit if shadowed field changed) and you are
> > not
> > > > concerned
> > > > about any merge/rebase mess. I will work on this direction.
> > > > I'll first send an independent patch to introduce the accessors. Once
> > you
> > > > apply this patch, I'll continue and send you v2 patches for shadow
> > vmcs.
> > > >
> > > > Do you agree ?
> > > Yes.
> > 
> > Looking again at the code it seems like we could avoid adding the
> > accessors.
> > We could just set a flag in nested_vmx_vmexit and
> > nested_vmx_entry_failure. Then, in vmx_vcpu_run we check/reset the flag and
> > call copy_vmcs12_to_shadow (if required).
> > 
> > What do you think ?
> Good idea! With accessors we can do further optimization by copying only
> things that changed, but it will be premature optimization at this
> point.
> 
Actually this is good idea only if we know for sure that VMX emulation
changes vmcs12 only during guest entry/exit. Is this the case? I think
so.

--
			Gleb.