linux-kernel - Re: [RFC PATCH v2 43/69] KVM: x86/mmu: Allow non-zero init value for shadow PTE

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Date:   Thu, 8 Jul 2021 08:20:12 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     isaku.yamahata@...el.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [RFC PATCH v2 43/69] KVM: x86/mmu: Allow non-zero init value for
 shadow PTE

On Tue, Jul 06, 2021 at 04:56:07PM +0200,
Paolo Bonzini <pbonzini@...hat.com> wrote:

> On 03/07/21 00:04, isaku.yamahata@...el.com wrote:
> > From: Sean Christopherson <sean.j.christopherson@...el.com>
> > 
> > TDX will run with EPT violation #VEs enabled, which means KVM needs to
> > set the "suppress #VE" bit in unused PTEs to avoid unintentionally
> > reflecting not-present EPT violations into the guest.
> > 
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> > ---
> >   arch/x86/kvm/mmu.h      |  1 +
> >   arch/x86/kvm/mmu/mmu.c  | 50 +++++++++++++++++++++++++++++++++++------
> >   arch/x86/kvm/mmu/spte.c | 10 +++++++++
> >   arch/x86/kvm/mmu/spte.h |  2 ++
> >   4 files changed, 56 insertions(+), 7 deletions(-)
> 
> Please ensure that this also works for tdp_mmu.c (if anything, consider
> supporting TDX only for TDP MMU; it's quite likely that mmu.c support for
> EPT/NPT will go away).

It's on my TODO list. Will address it.
-- 
Isaku Yamahata <isaku.yamahata@...il.com>