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=-13.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 C40E5C43461 for ; Fri, 11 Sep 2020 17:17:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86AA1221E7 for ; Fri, 11 Sep 2020 17:17:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fs5YqmN5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726191AbgIKRRR (ORCPT ); Fri, 11 Sep 2020 13:17:17 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:24436 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726230AbgIKRQi (ORCPT ); Fri, 11 Sep 2020 13:16:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599844594; 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=ZIYsyXJ8ywDIaj8FeKR2rSXn6BX0Y2iuA9bZ+7HRd1I=; b=fs5YqmN5ZMyeAVZd6znUoX7klJp+jOj48Mp6J3qFIT9pLE6wLlPvzDJ9g7x7zHrWEa6exH aGBp2THAd1gdA5zoblyAoayHY9z4tazBGRSZI2SQIH8drAZSIrjMCCD0W51/nKrdl1tNhi uZiFkWeVbR3e8N7EEOr5g8i1DmN7j2k= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-361-Vqdc0bFCPJeAjhSAvQrX6Q-1; Fri, 11 Sep 2020 13:16:30 -0400 X-MC-Unique: Vqdc0bFCPJeAjhSAvQrX6Q-1 Received: by mail-wr1-f69.google.com with SMTP id y3so3707728wrl.21 for ; Fri, 11 Sep 2020 10:16:30 -0700 (PDT) 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=ZIYsyXJ8ywDIaj8FeKR2rSXn6BX0Y2iuA9bZ+7HRd1I=; b=kNjHaxerAVqgWvxD0IBT+JalUV7jC6cn84NT+qKNJHD1wGAOHcVtHm256bJvie3xby 43UH7TeXvQa/n3G6UxEL5lLK4KLnrdJotEQS45aaARSqjSmSHijKEn+pyQcH+WIEloQ3 qhd7ZywIbxSUT32QpbDs5toz3WcLWuYPRgNx7raImybMrSbvYe9V0UssOTVBZFKvF8gb +gSwIulBUwfmteZk6l7gn+ORknJ+qZDh/aaRbcnOWylWDE+sRKHTM5tTMY7XsWGVpHZA jUB58haiakSx2HHNJjuS12irKGa75ma0N84ntnz9F6waX1gqzCdZ5Q4t7YVJ4Uidb4ur lbrQ== X-Gm-Message-State: AOAM531SVK8AAwFPuxFhEnJcoDWscjtgOpvoyEGuprUkSgnHqkxkUnKK YL3e4rsJnI08DAMn71FUKur1AXfbsmoRNRt5ATIfCfjguMFQ0PGTzzAFAz3mgdDZOJqWDj/GSkg Yg6SPrc0teUFjnDIclTOzzcK5 X-Received: by 2002:adf:f382:: with SMTP id m2mr2876489wro.327.1599844589610; Fri, 11 Sep 2020 10:16:29 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzLDVAzC6EF7s8wacyh/9QgVLvue/fSpLMye6yCXQhCyCcxkQfGHVkuy/JjDoAtwvRAvvpmuw== X-Received: by 2002:adf:f382:: with SMTP id m2mr2876470wro.327.1599844589410; Fri, 11 Sep 2020 10:16:29 -0700 (PDT) Received: from [192.168.10.150] ([93.56.170.5]) by smtp.gmail.com with ESMTPSA id v6sm5562089wrt.90.2020.09.11.10.16.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Sep 2020 10:16:28 -0700 (PDT) Subject: Re: [PATCH V2] kvm x86/mmu: use KVM_REQ_MMU_SYNC to sync when needed To: Lai Jiangshan , linux-kernel@vger.kernel.org Cc: Lai Jiangshan , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , kvm@vger.kernel.org References: <87y2ltx6gl.fsf@vitty.brq.redhat.com> <20200902135421.31158-1-jiangshanlai@gmail.com> From: Paolo Bonzini Message-ID: <35d079d4-6cb8-b2d0-a4d4-7be92b30a1ea@redhat.com> Date: Fri, 11 Sep 2020 19:16:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200902135421.31158-1-jiangshanlai@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/09/20 15:54, Lai Jiangshan wrote: > From: Lai Jiangshan > > When kvm_mmu_get_page() gets a page with unsynced children, the spt > pagetable is unsynchronized with the guest pagetable. But the > guest might not issue a "flush" operation on it when the pagetable > entry is changed from zero or other cases. The hypervisor has the > responsibility to synchronize the pagetables. > > The linux kernel behaves as above for many years, But > 8c8560b83390("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes) > inadvertently included a line of code to change it without giving any > reason in the changelog. It is clear that the commit's intention was to > change KVM_REQ_TLB_FLUSH -> KVM_REQ_TLB_FLUSH_CURRENT, so we don't > unneedlesly flush other contexts but one of the hunks changed > nearby KVM_REQ_MMU_SYNC instead. > > The this patch changes it back. > > Link: https://lore.kernel.org/lkml/20200320212833.3507-26-sean.j.christopherson@intel.com/ > Cc: Sean Christopherson > Cc: Vitaly Kuznetsov > Signed-off-by: Lai Jiangshan > --- > Changed from v1: > update patch description > > arch/x86/kvm/mmu/mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 4e03841f053d..9a93de921f2b 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -2468,7 +2468,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > } > > if (sp->unsync_children) > - kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); > + kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); > > __clear_sp_write_flooding_count(sp); > > Queued, thanks. Paolo