Re: [PATCH v2 6/6] KVM: Documentation: Add the missing description for tdp_mmu_page into kvm_mmu_page

[Sean Christopherson <seanjc@google.com>]

On Mon, Jun 26, 2023, Mingwei Zhang wrote:
> Add the description for tdp_mmu_page into kvm_mmu_page description.
> tdp_mmu_page is a field to differentiate shadow pages from TDP MMU and
> non-TDP MMU. When TDP MMU is enabled, sp->tdp_mmu_page=1 indicates a shadow
> page for L1, while sp->tdp_mmu_page=0 indicates a shadow page for an L2.
> When TDP MMU is disabled, sp->tdp_mmu_page is always 0. So update the doc
> to reflect the information.
> 
> Signed-off-by: Mingwei Zhang <mizhang@google.com>
> ---
>  Documentation/virt/kvm/x86/mmu.rst | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/x86/mmu.rst b/Documentation/virt/kvm/x86/mmu.rst
> index cc4bd190c93d..678dc0260a54 100644
> --- a/Documentation/virt/kvm/x86/mmu.rst
> +++ b/Documentation/virt/kvm/x86/mmu.rst
> @@ -278,6 +278,8 @@ Shadow pages contain the following information:
>      since the last time the page table was actually used; if emulation
>      is triggered too frequently on this page, KVM will unmap the page
>      to avoid emulation in the future.
> +  tdp_mmu_page:
> +    Is 1 if the shadow page is a TDP MMU page.

Maybe add a short blurb explaining that it's used for control flow when starting
from a common entry point?  E.g. walking page tables given a root, and walking
lists that can hold both shadow MMU and TDP MMU pages.