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[34.82.80.254]) by smtp.gmail.com with ESMTPSA id y7sm12164953pfi.204.2021.08.02.15.29.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Aug 2021 15:29:23 -0700 (PDT) Date: Mon, 2 Aug 2021 22:29:19 +0000 From: David Matlack To: Mingwei Zhang Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ben Gardon , Jing Zhang Subject: Re: [PATCH v3 1/3] KVM: x86/mmu: Remove redundant spte present check in mmu_set_spte Message-ID: References: <20210730225939.3852712-1-mizhang@google.com> <20210730225939.3852712-2-mizhang@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210730225939.3852712-2-mizhang@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jul 30, 2021 at 03:59:37PM -0700, Mingwei Zhang wrote: > Drop an unnecessary is_shadow_present_pte() check when updating the rmaps > after installing a non-MMIO SPTE. set_spte() is used only to create > shadow-present SPTEs, e.g. MMIO SPTEs are handled early on, mmu_set_spte() > runs with mmu_lock held for write, i.e. the SPTE can't be zapped between > writing the SPTE and updating the rmaps. > > Opportunistically combine the "new SPTE" logic for large pages and rmaps. > > No functional change intended. > > Suggested-by: Ben Gardon > > Reviewed-by: Ben Gardon > Reviewed-by: Sean Christopherson > Signed-off-by: Mingwei Zhang > --- Reviewed-by: David Matlack > arch/x86/kvm/mmu/mmu.c | 14 ++++++-------- > 1 file changed, 6 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index b888385d1933..442cc554ebd6 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -2690,15 +2690,13 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, > > pgprintk("%s: setting spte %llx\n", __func__, *sptep); > trace_kvm_mmu_set_spte(level, gfn, sptep); > - if (!was_rmapped && is_large_pte(*sptep)) > - ++vcpu->kvm->stat.lpages; > > - if (is_shadow_present_pte(*sptep)) { > - if (!was_rmapped) { > - rmap_count = rmap_add(vcpu, sptep, gfn); > - if (rmap_count > RMAP_RECYCLE_THRESHOLD) > - rmap_recycle(vcpu, sptep, gfn); > - } > + if (!was_rmapped) { > + if (is_large_pte(*sptep)) > + ++vcpu->kvm->stat.lpages; > + rmap_count = rmap_add(vcpu, sptep, gfn); > + if (rmap_count > RMAP_RECYCLE_THRESHOLD) > + rmap_recycle(vcpu, sptep, gfn); > } > > return ret; > -- > 2.32.0.554.ge1b32706d8-goog >