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[34.105.13.176]) by smtp.gmail.com with ESMTPSA id w16-20020a634750000000b00530621e5ee4sm4459318pgk.9.2023.06.26.10.55.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jun 2023 10:55:07 -0700 (PDT) Date: Mon, 26 Jun 2023 17:55:03 +0000 From: Mingwei Zhang To: "Huang, Kai" Cc: "pbonzini@redhat.com" , "Christopherson,, Sean" , "jmattson@google.com" , "kvm@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "dmatlack@google.com" , "bgardon@google.com" Subject: Re: [PATCH 4/6] KVM: Documentation: Add the missing tdp_mmu_root_count into kvm_mmu_page Message-ID: References: <20230618000856.1714902-1-mizhang@google.com> <20230618000856.1714902-5-mizhang@google.com> <1af0f4de320fd5ba96d63b7f0bdbbb061a7466f2.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1af0f4de320fd5ba96d63b7f0bdbbb061a7466f2.camel@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org 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 > > --- > > 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