linux-kernel - [PATCH v2 5/6] KVM: Documentation: Add the missing description for mmu_valid_gen into kvm_mmu

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Message-ID: <20230626182016.4127366-6-mizhang@google.com>
Date:   Mon, 26 Jun 2023 18:20:15 +0000
From:   Mingwei Zhang <mizhang@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, Mingwei Zhang <mizhang@...gle.com>,
        Kai Huang <kai.huang@...el.com>,
        Jim Mattson <jmattson@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Ben Gardon <bgardon@...gle.com>, Xu Yilun <yilun.xu@...el.com>,
        Zhi Wang <zhi.wang.linux@...il.com>
Subject: [PATCH v2 5/6] KVM: Documentation: Add the missing description for
 mmu_valid_gen into kvm_mmu_page

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@...gle.com>
Reviewed-by: Kai Huang <kai.huang@...el.com>
---
 Documentation/virt/kvm/x86/mmu.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/virt/kvm/x86/mmu.rst b/Documentation/virt/kvm/x86/mmu.rst
index 97d695207e11..cc4bd190c93d 100644
--- a/Documentation/virt/kvm/x86/mmu.rst
+++ b/Documentation/virt/kvm/x86/mmu.rst
@@ -208,6 +208,10 @@ 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=1).
+  mmu_valid_gen:
+    Used by comparing against kvm->arch.mmu_valid_gen to check whether the
+    shadow page is obsolete thus a convenient variable for fast zapping.
+    Note that TDP MMU does not use mmu_valid_gen.
   gfn:
     Either the guest page table containing the translations shadowed by this
     page, or the base page frame for linear translations.  See role.direct.
-- 
2.41.0.162.gfafddb0af9-goog