linux-kernel - Re: [PATCH v11 058/113] KVM: TDX: MTRR: implement get_mt

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Message-ID: <20230227221508.GS4175971@ls.amr.corp.intel.com>
Date:   Mon, 27 Feb 2023 14:15:08 -0800
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     Yuan Yao <yuan.yao@...ux.intel.com>
Cc:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
        Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH v11 058/113] KVM: TDX: MTRR: implement get_mt_mask() for
 TDX

On Fri, Feb 03, 2023 at 02:55:45PM +0800,
Yuan Yao <yuan.yao@...ux.intel.com> wrote:
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index e68816999387..c4c5a8f786c1 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -309,6 +309,25 @@ int tdx_vm_init(struct kvm *kvm)
> >  	return 0;
> >  }
> >
> > +u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
> > +{
> > +	/* TDX private GPA is always WB. */
> > +	if (gfn & kvm_gfn_shared_mask(vcpu->kvm)) {
> > +		WARN_ON_ONCE(is_mmio);
> > +		return  MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT;
> > +	}
> 
> This looks not clear enough, the comment says things about private GPA
> but the code returns WB for shared GPA, please align them.

It should be !(gfn & shared mask). Thanks for the catch.
-- 
Isaku Yamahata <isaku.yamahata@...il.com>