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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 210EAC433F5 for ; Wed, 16 Mar 2022 02:19:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348480AbiCPCVA (ORCPT ); Tue, 15 Mar 2022 22:21:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237405AbiCPCU6 (ORCPT ); Tue, 15 Mar 2022 22:20:58 -0400 Received: from mail-yw1-x1129.google.com (mail-yw1-x1129.google.com [IPv6:2607:f8b0:4864:20::1129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A25B4427CE; Tue, 15 Mar 2022 19:19:45 -0700 (PDT) Received: by mail-yw1-x1129.google.com with SMTP id 00721157ae682-2e59ea0f3d8so8313297b3.7; Tue, 15 Mar 2022 19:19:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=2wDOJfE8Udv/yPkkP//z7M6l01Skx49rMSVyt4RFfkk=; b=joGnnPIeYb+VlXp+ly8j/0oB5qBB3qaNJh0k/cLpE61oXjRpfr2OVYTdHqwm4hyLSg 1Bc0W3jnYw0d0kBXJ6PSvyDIzrUrQO4DGn0awBVEED2EpOgB14ixgrHd7dn+YTxkJ0ZL ldT0E3UDLviwkPNemhjQLp7MJJXHNdM5342Y4PlJB0HQjFDgT+x/UvAypwVQUXDc6Jf5 sYqz35ghl125FMfkGglJNm+AUimgLhX+9kEup89hvsqXouTeQLYePAFOnjhdnToy1J6j CllkkMQUYaUxGjLY58UYQGWcMMO2NQtkM/5cVWk0f+Ah8ztdGRQdvDl+ryhg5nKbi2rW NWLw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=2wDOJfE8Udv/yPkkP//z7M6l01Skx49rMSVyt4RFfkk=; b=yTEW7mEid4wt0t5yxuLYumyShRWcsR8mE1IBsvBv9rbcD90wSSR6pY91tMsND+JA+Y USCWyeqLjv7IXrNNNzyYwrr0F0FQng4Fy2HIBF2PS3vKibBTnZfXdYk1Auywk5vgqak9 ASoOVoudZtii+vCAxmgpRntP9NW5M4C6Icp4trVnEa1gYgmsos2jkwXdEgoigDAyEFy6 t3O2N4B/IVACHOjxmBtGO5lDPkaIRA0ANHt7AdrriuMT0EVlXDa3TlRxf7NHI/bXNiBQ YjL3QDEwkt5k3Wo+axX4b86iw5KRm/roL5d91l2T5hUFp67QqfYRB6inLATFEG8Trzje XSxg== X-Gm-Message-State: AOAM532Z5u73mDNDRg8l66WaTm5aEsaz+Dq4/hpalEPL7EK3tkfi4+nM ZajQBfy1GEcAwz3LfwPkj1H6sKsXb3CPbSAuC18= X-Google-Smtp-Source: ABdhPJw4huEMVFKmb4DDLz4qwY4nPYpek7DI+L85d5wjn5LwIdVaRy+YtAtrq+un+GInFq6nbuqV+PAXA+b1GQ4gGjI= X-Received: by 2002:a0d:eb02:0:b0:2e5:9d37:58ba with SMTP id u2-20020a0deb02000000b002e59d3758bamr2837723ywe.231.1647397184923; Tue, 15 Mar 2022 19:19:44 -0700 (PDT) MIME-Version: 1.0 References: <0dabeeb789f57b0d793f85d073893063e692032d.1647336064.git.houwenlong.hwl@antgroup.com> In-Reply-To: <0dabeeb789f57b0d793f85d073893063e692032d.1647336064.git.houwenlong.hwl@antgroup.com> From: Lai Jiangshan Date: Wed, 16 Mar 2022 10:19:33 +0800 Message-ID: Subject: Re: [PATCH] KVM: x86/mmu: Don't rebuild page when the page is synced and no tlb flushing is required To: Hou Wenlong Cc: kvm@vger.kernel.org, Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , X86 ML , "H. Peter Anvin" , Lai Jiangshan , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 15, 2022 at 6:45 PM Hou Wenlong wrote: > > Before Commit c3e5e415bc1e6 ("KVM: X86: Change kvm_sync_page() > to return true when remote flush is needed"), the return value > of kvm_sync_page() indicates whether the page is synced, and > kvm_mmu_get_page() would rebuild page when the sync fails. > But now, kvm_sync_page() returns false when the page is > synced and no tlb flushing is required, which leads to > rebuild page in kvm_mmu_get_page(). So return the return > value of mmu->sync_page() directly and check it in > kvm_mmu_get_page(). If the sync fails, the page will be > zapped and the invalid_list is not empty, so set flush as > true is accepted in mmu_sync_children(). > Good catch. Acked-by: Lai Jiangshan > Fixes: c3e5e415bc1e6 ("KVM: X86: Change kvm_sync_page() to return true when remote flush is needed") > Signed-off-by: Hou Wenlong > --- > arch/x86/kvm/mmu/mmu.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 3b8da8b0745e..8efd165ee27c 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -1866,17 +1866,14 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, > &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ > if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else > > -static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > +static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > struct list_head *invalid_list) The comments for FNAME(sync_page) can be copied here.