Re: [PATCH v10 2/9] KVM: Introduce per-page memory attributes

[Chao Peng]

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@xxxxxxxxxx>
> > Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> > Link: https://lore.kernel.org/all/Y2WB48kD0J4VGynX@xxxxxxxxxx/
> > ---
> >   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