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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id p16sm12367785edw.44.2021.01.26.06.14.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Jan 2021 06:14:28 -0800 (PST) Subject: Re: [PATCH 09/24] kvm: x86/mmu: Don't redundantly clear TDP MMU pt memory To: Ben Gardon , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Peter Xu , Sean Christopherson , Peter Shier , Peter Feiner , Junaid Shahid , Jim Mattson , Yulei Zhang , Wanpeng Li , Vitaly Kuznetsov , Xiao Guangrong References: <20210112181041.356734-1-bgardon@google.com> <20210112181041.356734-10-bgardon@google.com> From: Paolo Bonzini Message-ID: <48cafbae-3e73-d5ca-ddbc-13e1bbfafb2f@redhat.com> Date: Tue, 26 Jan 2021 15:14:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210112181041.356734-10-bgardon@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 12/01/21 19:10, Ben Gardon wrote: > The KVM MMU caches already guarantee that shadow page table memory will > be zeroed, so there is no reason to re-zero the page in the TDP MMU page > fault handler. > > No functional change intended. > > Reviewed-by: Peter Feiner > > Signed-off-by: Ben Gardon > --- > arch/x86/kvm/mmu/tdp_mmu.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 411938e97a00..55df596696c7 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -665,7 +665,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > list_add(&sp->link, &vcpu->kvm->arch.tdp_mmu_pages); > child_pt = sp->spt; > - clear_page(child_pt); > new_spte = make_nonleaf_spte(child_pt, > !shadow_accessed_mask); > > Queued, thanks. Paolo