From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E796BC433E0 for ; Tue, 26 Jan 2021 14:18:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBB8922B51 for ; Tue, 26 Jan 2021 14:18:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405786AbhAZOSQ (ORCPT ); Tue, 26 Jan 2021 09:18:16 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44630 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405624AbhAZOP7 (ORCPT ); Tue, 26 Jan 2021 09:15:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611670473; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VDatwy9yr1egcmeaxWIyYl6nPc9FqgpaSNtd+mv8gY0=; b=cf7EpmXHP9qm3hsGYhriF4k+Oe0ZY2m4z20hp8Dxdz5x8vqFKsQhuqh6FqGHXzOEYoYWBD m+yy3wMmqrTKu2BC+sk2Sbe/QSnZ6Jhi3/NvJPcU2hG3AIn4kK2ky4DeTWkA9lYaYbh5gb G7Nda6trUO1R1+/INzkB5m0sXGOXKMk= Received: from mail-ej1-f71.google.com (mail-ej1-f71.google.com [209.85.218.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-577-emuljht2MsKMBc_w_5q9Hg-1; Tue, 26 Jan 2021 09:14:30 -0500 X-MC-Unique: emuljht2MsKMBc_w_5q9Hg-1 Received: by mail-ej1-f71.google.com with SMTP id jg11so4991100ejc.23 for ; Tue, 26 Jan 2021 06:14:29 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=VDatwy9yr1egcmeaxWIyYl6nPc9FqgpaSNtd+mv8gY0=; b=tPbNIGYC9akunFisw4edJkUjiUXT8a2kpFY8AM5LQCt2L7zXr74vy/CMWacHvfLOK9 R2MTWA2hhrv0hryRaPcVFdmOXbM9Jh2Y5cyF9zWF0LvNS3DkQbZQyQ+k9m7c0hF41tTz nd8st18XNA3aM4y0WiQu2HfgfKd6iBIWE1Z45kcQ0lOEni562tzxbzptvulqOhBIEbXu KmXLzp/XW1Lq7dvkvmp958dC1tJO4nqagQ9WufsyOSNy/GDqLDHGC9t5YxK9HrOam8mJ oFWTGmOsOy1iWVzdQn1J2fX9xUgT4UFUkJvb3i1MXZgDKYq9hPoxaq/AJLGkrswyitJS 5EvQ== X-Gm-Message-State: AOAM533OYryJlK911lpCxPxW5MnAkCC81tLsraY/pdgqPhtR3NdJ5N+i mzF6Hut0arMsirFw3ssJA8fVWZOKuJM9DdZNucdys9Q6NERy72JGLkTm35Mhm4hf7GxzjDUHm85 Vsh3rC1fwXkcezkuGKBWNtw76 X-Received: by 2002:a17:906:af41:: with SMTP id ly1mr3418966ejb.491.1611670469049; Tue, 26 Jan 2021 06:14:29 -0800 (PST) X-Google-Smtp-Source: ABdhPJxLZHvvd991wi5LSYomm6Tr/MOTO7vpWabw8m6oShLXFqGN22xFOyRlIE7vZuC2Ph16eIU8NQ== X-Received: by 2002:a17:906:af41:: with SMTP id ly1mr3418953ejb.491.1611670468904; Tue, 26 Jan 2021 06:14:28 -0800 (PST) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([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: linux-kernel@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