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

Mingwei Zhang
2023-06-18T00:09:32Z

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
+ 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
--
2.41.0.162.gfafddb0af9-goog