From patchwork Tue Mar 15 09:35:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Wenlong X-Patchwork-Id: 12781223 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 B2769C433F5 for ; Tue, 15 Mar 2022 09:35:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346661AbiCOJge (ORCPT ); Tue, 15 Mar 2022 05:36:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238684AbiCOJgb (ORCPT ); Tue, 15 Mar 2022 05:36:31 -0400 Received: from out0-153.mail.aliyun.com (out0-153.mail.aliyun.com [140.205.0.153]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 266884BFD2; Tue, 15 Mar 2022 02:35:18 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R271e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018047212;MF=houwenlong.hwl@antgroup.com;NM=1;PH=DS;RN=15;SR=0;TI=SMTPD_---.N4z7UFy_1647336913; Received: from localhost(mailfrom:houwenlong.hwl@antgroup.com fp:SMTPD_---.N4z7UFy_1647336913) by smtp.aliyun-inc.com(127.0.0.1); Tue, 15 Mar 2022 17:35:14 +0800 From: "Hou Wenlong" To: kvm@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Lai Jiangshan , linux-kernel@vger.kernel.org Subject: [PATCH] KVM: x86/mmu: Don't rebuild page when the page is synced and no tlb flushing is required Date: Tue, 15 Mar 2022 17:35:13 +0800 Message-Id: <0dabeeb789f57b0d793f85d073893063e692032d.1647336064.git.houwenlong.hwl@antgroup.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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(). Fixes: c3e5e415bc1e6 ("KVM: X86: Change kvm_sync_page() to return true when remote flush is needed") Signed-off-by: Hou Wenlong Acked-by: Lai Jiangshan Reported-by: Hou Wenlong Signed-off-by: Sean Christopherson --- 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) { int ret = vcpu->arch.mmu->sync_page(vcpu, sp); - if (ret < 0) { + if (ret < 0) kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list); - return false; - } - - return !!ret; + return ret; } static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, @@ -2039,6 +2036,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, struct hlist_head *sp_list; unsigned quadrant; struct kvm_mmu_page *sp; + int ret; int collisions = 0; LIST_HEAD(invalid_list); @@ -2091,11 +2089,13 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, * If the sync fails, the page is zapped. If so, break * in order to rebuild it. */ - if (!kvm_sync_page(vcpu, sp, &invalid_list)) + ret = kvm_sync_page(vcpu, sp, &invalid_list); + if (ret < 0) break; WARN_ON(!list_empty(&invalid_list)); - kvm_flush_remote_tlbs(vcpu->kvm); + if (ret > 0) + kvm_flush_remote_tlbs(vcpu->kvm); } __clear_sp_write_flooding_count(sp);