Re: [PATCH 4/6] KVM: Documentation: Add the missing tdp_mmu_root_count into kvm_mmu_page

Mingwei Zhang
2023-06-26T17:55:48Z

On Thu, Jun 22, 2023, Huang, Kai wrote:
> On Sun, 2023-06-18 at 00:08 +0000, Mingwei Zhang wrote:
> > Add tdp_mmu_root_count into kvm_mmu_page description. tdp_mmu_root_count is
> > an atomic counter used only in TDP MMU. Its usage and meaning is slightly
> > different with root_counter in shadow MMU. Update the doc.
> >
> > Signed-off-by: Mingwei Zhang <mizhang@google.com>
> > ---
> > Documentation/virt/kvm/x86/mmu.rst | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/Documentation/virt/kvm/x86/mmu.rst b/Documentation/virt/kvm/x86/mmu.rst
> > index 36bfe0fe02bb..3dce2426ad6d 100644
> > --- a/Documentation/virt/kvm/x86/mmu.rst
> > +++ b/Documentation/virt/kvm/x86/mmu.rst
> > @@ -230,6 +230,12 @@ Shadow pages contain the following information:
> > A counter keeping track of how many hardware registers (guest cr3 or
> > pdptrs) are now pointing at the page. While this counter is nonzero, the
> > page cannot be destroyed. See role.invalid.
> > + tdp_mmu_root_count:
> > + An atomic reference counter in TDP MMU that allows for parallel
> ^
> Please explicitly say "TDP MMU root page" ?
>
> > + accesses. Accessing the page requires lifting the counter value. The
> > + initial value is set as 2 indicating one reference from vCPU and one
> ^
> to ?
>
> > + from TDP MMU itself.
> >
>
>
> > While this counter is nonzero, the page cannot be
> > + destroyed.
> >
>
> I guess this sentence is implied by "reference counter" mentioned in the first
> sentence.
>

Will make the changes in next version.

-Mingwei