Add mmu_valid_gen into kvm_mmu_page description. mmu_valid_gen is used in
shadow MMU for fast zapping. Update the doc to reflect that.

Signed-off-by: Mingwei Zhang <mizhang@google.com>
---
 Documentation/virt/kvm/x86/mmu.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/virt/kvm/x86/mmu.rst b/Documentation/virt/kvm/x86/mmu.rst
index 3dce2426ad6d..0dbdb7fb8cc6 100644
--- a/Documentation/virt/kvm/x86/mmu.rst
+++ b/Documentation/virt/kvm/x86/mmu.rst
@@ -208,6 +208,10 @@ Shadow pages contain the following information:
     The page is not backed by a guest page table, but its first entry
     points to one.  This is set if NPT uses 5-level page tables (host
     CR4.LA57=1) and is shadowing L1's 4-level NPT (L1 CR4.LA57=1).
+  mmu_valid_gen:
+    Used by comparing against kvm->arch.mmu_valid_gen to check whether the
+    shadow page is obsolete thus a convenient variable for fast zapping.
+    Note that TDP MMU does not use mmu_valid_gen.
   gfn:
     Either the guest page table containing the translations shadowed by this
     page, or the base page frame for linear translations.  See role.direct.
-- 
2.41.0.162.gfafddb0af9-goog

On Sun, 2023-06-18 at 00:08 +0000, Mingwei Zhang wrote:
> Add mmu_valid_gen into kvm_mmu_page description. mmu_valid_gen is used in
> shadow MMU for fast zapping. Update the doc to reflect that.
> 
> Signed-off-by: Mingwei Zhang <mizhang@google.com>
> ---
>  Documentation/virt/kvm/x86/mmu.rst | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/x86/mmu.rst b/Documentation/virt/kvm/x86/mmu.rst
> index 3dce2426ad6d..0dbdb7fb8cc6 100644
> --- a/Documentation/virt/kvm/x86/mmu.rst
> +++ b/Documentation/virt/kvm/x86/mmu.rst
> @@ -208,6 +208,10 @@ Shadow pages contain the following information:
>      The page is not backed by a guest page table, but its first entry
>      points to one.  This is set if NPT uses 5-level page tables (host
>      CR4.LA57=1) and is shadowing L1's 4-level NPT (L1 CR4.LA57=1).
> +  mmu_valid_gen:
> +    Used by comparing against kvm->arch.mmu_valid_gen to check whether the
> +    shadow page is obsolete thus a convenient variable for fast zapping.
> +    Note that TDP MMU does not use mmu_valid_gen.
>    gfn:
>      Either the guest page table containing the translations shadowed by this
>      page, or the base page frame for linear translations.  See role.direct.

Reviewed-by: Kai Huang <kai.huang@intel.com>