linux-kernel - Re: [PATCH v2 05/10] KVM: x86/mmu: Introduce kvm_tdp_map

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Message-ID: <20240417183908.GG3039520@ls.amr.corp.intel.com>
Date: Wed, 17 Apr 2024 11:39:08 -0700
From: Isaku Yamahata <isaku.yamahata@...el.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"Yamahata, Isaku" <isaku.yamahata@...el.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>,
	"Huang, Kai" <kai.huang@...el.com>,
	"federico.parola@...ito.it" <federico.parola@...ito.it>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
	"dmatlack@...gle.com" <dmatlack@...gle.com>,
	"michael.roth@....com" <michael.roth@....com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>,
	isaku.yamahata@...ux.intel.com
Subject: Re: [PATCH v2 05/10] KVM: x86/mmu: Introduce kvm_tdp_map_page() to
 populate guest memory

On Tue, Apr 16, 2024 at 02:46:17PM +0000,
"Edgecombe, Rick P" <rick.p.edgecombe@...el.com> wrote:

> On Wed, 2024-04-10 at 15:07 -0700, isaku.yamahata@...el.com wrote:
> >  
> > +int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code,
> > +                    u8 *level)
> > +{
> > +       int r;
> > +
> > +       /* Restrict to TDP page fault. */
> > +       if (vcpu->arch.mmu->page_fault != kvm_tdp_page_fault)
> > +               return -EINVAL;
> > +
> > +       r = __kvm_mmu_do_page_fault(vcpu, gpa, error_code, false, NULL,
> > level);
> 
> Why not prefetch = true? Doesn't it fit? It looks like the behavior will be to
> not set the access bit.

Makes sense. Yes, the difference is to set A/D bit or not.
-- 
Isaku Yamahata <isaku.yamahata@...el.com>