diff mbox series

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

Message ID 20230618000856.1714902-5-mizhang@google.com
State New
Headers
Series KVM: Documentation: Update document description for kvm_mmu_page and kvm_mmu_page_role |

Commit Message

Mingwei Zhang June 18, 2023, 12:08 a.m. UTC 
  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(+)

Comments

Kai Huang June 22, 2023, 8:37 a.m. UTC | #1 
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.

> Note this field is a union with root_count.
>
Mingwei Zhang June 26, 2023, 5:55 p.m. UTC | #2 
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
diff mbox series

Patch

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
+    accesses.  Accessing the page requires lifting the counter value. The
+    initial value is set as 2 indicating one reference from vCPU and one
+    from TDP MMU itself. While this counter is nonzero, the page cannot be
+    destroyed. Note this field is a union with root_count.
   parent_ptes:
     The reverse mapping for the pte/ptes pointing at this page's spt. If
     parent_ptes bit 0 is zero, only one spte points at this page and