linux-kernel - Re: [PATCH v7 033/102] KVM: x86/mmu: Add address conversion functions for TDX shared bits

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Date:   Wed, 13 Jul 2022 17:14:46 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     Kai Huang <kai.huang@...el.com>
Cc:     Isaku Yamahata <isaku.yamahata@...il.com>,
        isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>
Subject: Re: [PATCH v7 033/102] KVM: x86/mmu: Add address conversion
 functions for TDX shared bits

On Wed, Jul 13, 2022 at 10:41:33PM +1200,
Kai Huang <kai.huang@...el.com> wrote:

> 
> > > 
> > > And by applying this patch, nothing will prevent you to turn on INTEL_TDX_HOST
> > > and KVM_INTEL, which also turns on KVM_MMU_PRIVATE.
> > > 
> > > So 'kvm_arch::gfn_shared_mask' is guaranteed to be 0?  If not, can legal
> > > (shared) GFN for normal VM be potentially treated as private?
> > > 
> > > If yes, perhaps explicitly call out in changelog so people don't need to worry
> > > about?
> > 
> > struct kvm that includes struct kvm_arch is guaranteed to be zero.
> > 
> > Here is the updated commit message.
> > 
> > Author: Isaku Yamahata <isaku.yamahata@...el.com>
> > Date:   Tue Jul 12 00:10:13 2022 -0700
> > 
> >     KVM: x86/mmu: Add address conversion functions for TDX shared bit of GPA
> >     
> >     TDX repurposes one GPA bit (51 bit or 47 bit based on configuration) to
> >     indicate the GPA is private(if cleared) or shared (if set) with VMM.  If
> >     GPA.shared is set, GPA is converted existing conventional EPT pointed by
> >     EPTP.  If GPA.shared bit is cleared, GPA is converted by TDX module.
> >     VMM has to issue SEAMCALLs to operate.
> 
> Sorry what does "GPA is converted ..." mean?

Oops. typo. I meant GPA is covered by ...

-- 
Isaku Yamahata <isaku.yamahata@...il.com>