From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH v3 03/13] nEPT: Add EPT tables support to paging_tmpl.h
Date: Wed, 22 May 2013 09:16:49 +0300
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Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
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	Paolo Bonzini <pbonzini@redhat.com>
To: "Nakajima, Jun" <jun.nakajima@intel.com>
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On Tue, May 21, 2013 at 03:26:18PM -0700, Nakajima, Jun wrote:
> On Tue, May 21, 2013 at 4:05 AM, Xiao Guangrong
> <xiaoguangrong@linux.vnet.ibm.com> wrote:
> > On 05/21/2013 05:01 PM, Gleb Natapov wrote:
> >> On Tue, May 21, 2013 at 04:30:13PM +0800, Xiao Guangrong wrote:
> >>>>> @@ -772,6 +810,7 @@ static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gva_t vaddr,
> >>>>>
> >>>>>    return gpa;
> >>>>>  }
> >>>>> +#endif
> >>>>
> >>>> Strange!
> >>>>
> >>>> Why does nested ept not need these functions? How to emulate the instruction faulted on L2?
> >>>
> >>> Sorry, i misunderstood it. Have found the reason out.
> >>>
> >> You can write it down here for future reviewers :)
> >
> > Okay.
> >
> > The functions used to translate L2's gva to L1's gpa are paging32_gva_to_gpa_nested
> > and paging64_gva_to_gpa_nested which are created by PTTYPE == 32 and PTTYPE == 64.
> >
> >
> 
> Back to your comments on PT_MAX_FULL_LEVELS:
> > +     #ifdef CONFIG_X86_64
> > +     #define PT_MAX_FULL_LEVELS 4
> > +     #define CMPXCHG cmpxchg
> > +     #else
> > +     #define CMPXCHG cmpxchg64
> > +    #define PT_MAX_FULL_LEVELS 2
> I don't think we need to support nEPT on 32-bit hosts.  So, I plan to
> remove such code. What do you think?
> 
Why shouldn't we support nEPT on 32-bit hosts?

--
			Gleb.