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Date:   Tue, 1 Dec 2020 09:31:08 +0800
From:   Lai Jiangshan <>
To:     Sean Christopherson <>
Cc:     Paolo Bonzini <>,
        LKML <>,,
        Lai Jiangshan <>,
        Jonathan Corbet <>,
        Sean Christopherson <>,
        Vitaly Kuznetsov <>,
        Wanpeng Li <>,
        Jim Mattson <>,
        Joerg Roedel <>,
        Thomas Gleixner <>,
        Ingo Molnar <>, Borislav Petkov <>,
        X86 ML <>, "H. Peter Anvin" <>,
        Avi Kivity <>,
Subject: Re: [PATCH] kvm/x86/mmu: use the correct inherited permissions to get
 shadow page

On Tue, Dec 1, 2020 at 1:41 AM Sean Christopherson <> wrote:

> Hmm, yes, KVM would incorrectly handle this scenario.  But, the proposed patch
> would not address the issue as KVM always maps non-leaf shadow pages with full
> access permissions.

Is it possible to exactly copy the access permissions from the guest
for non-leaf
shadow pages? Any protection from hypervisor (such as dirty track,
can only play on the leaf shadow ptes.

> Can we have a testcase in kvm-unit-tests?  It's okay of course if it
> only fails with ept=0.

Yes, it may have a flaw with ept=0. I don't get what "It's okay of course"
means. Is it related to kvm-unit-tests? Or no cloud provider uses

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