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

Chao Peng
2023-01-17T13:38:43Z

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