Add the description for 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@xxxxxxxxxx>
Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx>
---
Documentation/virt/kvm/x86/mmu.rst | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/Documentation/virt/kvm/x86/mmu.rst b/Documentation/virt/kvm/x86/mmu.rst
index 4a82fa016833..16d5d6a1c174 100644
--- a/Documentation/virt/kvm/x86/mmu.rst
+++ b/Documentation/virt/kvm/x86/mmu.rst
@@ -208,6 +208,16 @@ 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=0).
+ mmu_valid_gen:
+ The MMU generation of this page, used to fast zap of all MMU pages within a
+ VM without blocking vCPUs too long. Specifically, KVM updates the per-VM
+ valid MMU generation which causes the mismatch of mmu_valid_gen for each mmu
+ page. This makes all existing MMU pages obsolete. Obsolete pages can't be
+ used. Therefore, vCPUs must load a new, valid root before re-entering the
+ guest. The MMU generation is only ever '0' or '1'. Note, the TDP MMU doesn't
+ use this field as non-root TDP MMU pages are reachable only from their
+ owning root. Thus it suffices for TDP MMU to use role.invalid in root pages
+ to invalidate all MMU pages.
gfn:
Either the guest page table containing the translations shadowed by this
page, or the base page frame for linear translations. See role.direct.
--
2.42.0.283.g2d96d420d3-goog
