diff mbox series

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

Message ID 20230626182016.4127366-7-mizhang@google.com
State New
Headers
Series Update document description for kvm_mmu_page and kvm_mmu_page_role |

Commit Message

Mingwei Zhang June 26, 2023, 6:20 p.m. UTC 
  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(+)

Comments

Kai Huang June 26, 2023, 10:23 p.m. UTC | #1 
On Mon, 2023-06-26 at 18:20 +0000, 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.
>  
>  Reverse map
>  ===========
> -- 
> 2.41.0.162.gfafddb0af9-goog
> 

Reviewed-by: Kai Huang <kai.huang@intel.com>
Sean Christopherson June 27, 2023, 4:16 p.m. UTC | #2 
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.
Mingwei Zhang July 31, 2023, 10:28 p.m. UTC | #3 
On Tue, Jun 27, 2023, Sean Christopherson wrote:
> 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.

will do. Thanks.
diff mbox series

Patch

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.
 
 Reverse map
 ===========