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Date:   Tue, 17 Jan 2023 21:30:15 +0800
From:   Chao Peng <chao.p.peng@linux.intel.com>
To:     Binbin Wu <binbin.wu@linux.intel.com>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
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        Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
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        Wanpeng Li <wanpengli@tencent.com>,
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Subject: Re: [PATCH v10 2/9] KVM: Introduce per-page memory attributes
Message-ID: <20230117133015.GE273037@chaop.bj.intel.com>
Reply-To: Chao Peng <chao.p.peng@linux.intel.com>
References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com>
 <20221202061347.1070246-3-chao.p.peng@linux.intel.com>
 <c25f1f8c-f7c0-6a96-cd67-260df47f79a9@linux.intel.com>
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On Tue, Jan 17, 2023 at 11:21:10AM +0800, Binbin Wu wrote:
> 
> On 12/2/2022 2:13 PM, Chao Peng wrote:
> > In confidential computing usages, whether a page is private or shared is
> > necessary information for KVM to perform operations like page fault
> > handling, page zapping etc. There are other potential use cases for
> > per-page memory attributes, e.g. to make memory read-only (or no-exec,
> > or exec-only, etc.) without having to modify memslots.
> > 
> > Introduce two ioctls (advertised by KVM_CAP_MEMORY_ATTRIBUTES) to allow
> > userspace to operate on the per-page memory attributes.
> >    - KVM_SET_MEMORY_ATTRIBUTES to set the per-page memory attributes to
> >      a guest memory range.
> >    - KVM_GET_SUPPORTED_MEMORY_ATTRIBUTES to return the KVM supported
> >      memory attributes.
> > 
> > KVM internally uses xarray to store the per-page memory attributes.
> > 
> > Suggested-by: Sean Christopherson <seanjc@google.com>
> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> > Link: https://lore.kernel.org/all/Y2WB48kD0J4VGynX@google.com/
> > ---
> >   Documentation/virt/kvm/api.rst | 63 ++++++++++++++++++++++++++++
> >   arch/x86/kvm/Kconfig           |  1 +
> >   include/linux/kvm_host.h       |  3 ++
> >   include/uapi/linux/kvm.h       | 17 ++++++++
> 
> Should the changes introduced in this file also need to be added in
> tools/include/uapi/linux/kvm.h ?

Yes I think. But I'm hesitate to include in this patch or not. I see
many commits sync kernel kvm.h to tools's copy. Looks that is done
periodically and with a 'pull' model.

Chao