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Message-ID: <9e01bc014df60e215ba17432c06b6854f6dae3f8.camel@intel.com>
Subject: Re: [RFC PATCH v5 032/104] KVM: x86/mmu: introduce config for
 PRIVATE KVM MMU
From:   Kai Huang <kai.huang@intel.com>
To:     Isaku Yamahata <isaku.yamahata@gmail.com>
Cc:     isaku.yamahata@intel.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        Jim Mattson <jmattson@google.com>, erdemaktas@google.com,
        Connor Kuehl <ckuehl@redhat.com>,
        Sean Christopherson <seanjc@google.com>
Date:   Fri, 01 Apr 2022 15:13:27 +1300
In-Reply-To: <20220401015130.GE2084469@ls.amr.corp.intel.com>
References: <cover.1646422845.git.isaku.yamahata@intel.com>
         <770235e7fed04229b81c334e2477374374cea901.1646422845.git.isaku.yamahata@intel.com>
         <55fa888b31bae80bf72cbdbdf6f27401ea4ccc5c.camel@intel.com>
         <20220401015130.GE2084469@ls.amr.corp.intel.com>
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On Thu, 2022-03-31 at 18:51 -0700, Isaku Yamahata wrote:
> On Fri, Apr 01, 2022 at 12:23:28AM +1300,
> Kai Huang <kai.huang@intel.com> wrote:
> 
> > On Fri, 2022-03-04 at 11:48 -0800, isaku.yamahata@intel.com wrote:
> > > From: Isaku Yamahata <isaku.yamahata@intel.com>
> > > 
> > > To Keep the case of non TDX intact, introduce a new config option for
> > > private KVM MMU support.  At the moment, this is synonym for
> > > CONFIG_INTEL_TDX_HOST && CONFIG_KVM_INTEL.  The new flag make it clear
> > > that the config is only for x86 KVM MMU.
> > > 
> > > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> > > ---
> > >  arch/x86/kvm/Kconfig | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
> > > index 2b1548da00eb..2db590845927 100644
> > > --- a/arch/x86/kvm/Kconfig
> > > +++ b/arch/x86/kvm/Kconfig
> > > @@ -136,4 +136,8 @@ config KVM_MMU_AUDIT
> > >  config KVM_EXTERNAL_WRITE_TRACKING
> > >  	bool
> > >  
> > > +config KVM_MMU_PRIVATE
> > > +	def_bool y
> > > +	depends on INTEL_TDX_HOST && KVM_INTEL
> > > +
> > >  endif # VIRTUALIZATION
> > 
> > I am really not sure why need this.  Roughly looking at MMU related patches this
> > new config option is hardly used.  You have many code changes related to
> > handling private/shared but they are not under this config option.
> 
> I don't want to use CONFIG_INTEL_TDX_HOST in KVM MMU code.  I think the change
> to KVM MMU should be a sort of independent from TDX.  But it seems failed based
> on your feedback.

Why do you need to use any config?  As I said majority of your changes to MMU
are not under any config.  But I'll leave this to maintainer/reviewers. 

-- 
Thanks,
-Kai