Commit 6a713928 authored by Mingwei Zhang's avatar Mingwei Zhang Committed by Sean Christopherson
Browse files

KVM: Documentation: Add the missing description for tdp_mmu_root_count into kvm_mmu_page 



Add the description of tdp_mmu_root_count into kvm_mmu_page description and
combine it with the description of root_count. tdp_mmu_root_count is an
atomic counter used only in TDP MMU. Update the doc.

Signed-off-by: default avatarMingwei Zhang <mizhang@google.com>
Reviewed-by: default avatarKai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20230912184553.1887764-5-mizhang@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent b40a2455

Documentation/virt/kvm/x86/mmu.rst

+7 −4
Original line number Diff line number Diff line
@@ -229,10 +229,13 @@ Shadow pages contain the following information: 
    can be calculated from the gfn field when used.  In addition, when

    role.direct is set, KVM does not track access permission for each of the

    gfn. See role.direct and gfn.

  root_count:

    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.

  root_count / tdp_mmu_root_count:

     root_count is a reference counter for root shadow pages in Shadow MMU.

     vCPUs elevate the refcount when getting a shadow page that will be used as

     a root page, i.e. page that will be loaded into hardware directly (CR3,

     PDPTRs, nCR3 EPTP). Root pages cannot be destroyed while their refcount is

     non-zero. See role.invalid. tdp_mmu_root_count is similar but exclusively

     used in TDP MMU as an atomic refcount.

  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