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Date: Mon, 22 Apr 2024 10:30:13 -0700
From: Isaku Yamahata <isaku.yamahata@intel.com>
To: Yan Zhao <yan.y.zhao@intel.com>
Cc: isaku.yamahata@intel.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com,
	Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
	Sean Christopherson <seanjc@google.com>,
	Sagi Shahar <sagis@google.com>, Kai Huang <kai.huang@intel.com>,
	chen.bo@intel.com, hang.yuan@intel.com, tina.zhang@intel.com,
	Binbin Wu <binbin.wu@linux.intel.com>,
	isaku.yamahata@linux.intel.com
Subject: Re: [PATCH v19 058/130] KVM: x86/mmu: Add a private pointer to
 struct kvm_mmu_page
Message-ID: <20240422173013.GJ3596705@ls.amr.corp.intel.com>
References: <cover.1708933498.git.isaku.yamahata@intel.com>
 <9d86b5a2787d20ffb5a58f86e43601a660521f16.1708933498.git.isaku.yamahata@intel.com>
 <ZiXautOkEweWfUL0@yzhao56-desk.sh.intel.com>
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On Mon, Apr 22, 2024 at 11:34:18AM +0800,
Yan Zhao <yan.y.zhao@intel.com> wrote:

> On Mon, Feb 26, 2024 at 12:26:00AM -0800, isaku.yamahata@intel.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@intel.com>
> > +static inline void *kvm_mmu_private_spt(struct kvm_mmu_page *sp)
> > +{
> > +	return sp->private_spt;
> > +}
> > +
> > +static inline void kvm_mmu_init_private_spt(struct kvm_mmu_page *sp, void *private_spt)
> > +{
> > +	sp->private_spt = private_spt;
> > +}
> This function is actually not used for initialization.
> Instead, it's only called after failure of free_private_spt() in order to
> intentionally leak the page to prevent kernel from accessing the encrypted page.
> 
> So to avoid confusion, how about renaming it to kvm_mmu_leak_private_spt() and
> always resetting the pointer to NULL?
> 
> static inline void kvm_mmu_leak_private_spt(struct kvm_mmu_page *sp)
> {
> 	sp->private_spt = NULL;
> }

The older version had a config to disable TDX TDP MMU at a compile time.  Now
we dropped the config so that we don't necessarily need wrapper function with
#ifdef. Now we have only single caller, I'll eliminate this wrapper function
(and related wrapper functions) by open code.
-- 
Isaku Yamahata <isaku.yamahata@intel.com>