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=-7.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 35C1BC433B4 for ; Mon, 3 May 2021 13:42:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0CC661026 for ; Mon, 3 May 2021 13:42:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234369AbhECNnY (ORCPT ); Mon, 3 May 2021 09:43:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:29830 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234373AbhECNnV (ORCPT ); Mon, 3 May 2021 09:43:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620049348; 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=IOqsilqvn+aRNNXngzMn1OYzuH7ToC3yrg+kEaYj+1g=; b=DfSyFZzkjK6crwUZDl72B4zuy/n9jpuppsOeFpwDJuLFZEwwunNfnOVRAipva6ld2iTuP7 CfLxHZh6IxCft/aaiR+3ymbcZsdo/sZPSUlHtj8XzvYGq4QZvz4UMQNG8WP9MIlQCzhOdn q72TcE4+S6g2t3x3aXlwvMNpN2++4iM= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-494--n9EI8DLNFyibqFap02nFA-1; Mon, 03 May 2021 09:42:24 -0400 X-MC-Unique: -n9EI8DLNFyibqFap02nFA-1 Received: by mail-ed1-f69.google.com with SMTP id d8-20020a0564020008b0290387d38e3ce0so4564999edu.1 for ; Mon, 03 May 2021 06:42:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=IOqsilqvn+aRNNXngzMn1OYzuH7ToC3yrg+kEaYj+1g=; b=tidFwUtJdtj1998RpkSMzWWVclX/gjFu+ClbkurBGYFBVjds3vYX1vwroQzk41aS0b 0f0c45r5wtKxxNkk6WRyZFHSGWUqb5Ms1hX6f4KynQVA60q6lGE0bp8EVxK5Y1iIybD+ EJKKp5xCcTnup2xUkOmm/rOiS2jM2t3sRHil4gG5R+09OcDeQfMrcLQDrVt805HjuK5z 3/1pwjG17HqSfc4iEuW8zcXsKNIgOwTP9phz6y/lVObWdHh8yk2ayP7ExztiybNLnOVv 0bvDm0O/kLFlHaqWvhOZQOeVZfcC7y7JMXXnQoiV1lPL48EDRhV7oaF3amFJrkY7uCHj swVA== X-Gm-Message-State: AOAM5329KOA3Xms3QlWJEs/hJFmhkZogsV8PBtXLplrU9coyNvGAa43L eh/IesiJDyUGQfxSd3G+5ZMVdwGqTjSAqk/bMKOFBRkPdC5Ia+M706pwPxOdeJaGHsPCiNxPoU9 pgDliuJlbdbGX5SlwebXvNj16 X-Received: by 2002:a50:82e2:: with SMTP id 89mr19872363edg.0.1620049343335; Mon, 03 May 2021 06:42:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzk3YnveQIawNQR3cb7zFFkOhqqtODvwbejBqHjpAgxGkRH2eHVwNnMVOHCGoASejb2epmncQ== X-Received: by 2002:a50:82e2:: with SMTP id 89mr19872346edg.0.1620049343181; Mon, 03 May 2021 06:42:23 -0700 (PDT) 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 c25sm12614554edt.43.2021.05.03.06.42.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 May 2021 06:42:22 -0700 (PDT) To: Ben Gardon , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Peter Xu , Sean Christopherson , Peter Shier , Junaid Shahid , Jim Mattson , Yulei Zhang , Wanpeng Li , Vitaly Kuznetsov , Xiao Guangrong References: <20210429211833.3361994-1-bgardon@google.com> <20210429211833.3361994-2-bgardon@google.com> From: Paolo Bonzini Subject: Re: [PATCH v2 1/7] KVM: x86/mmu: Track if shadow MMU active Message-ID: Date: Mon, 3 May 2021 15:42:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210429211833.3361994-2-bgardon@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/04/21 23:18, Ben Gardon wrote: > +void activate_shadow_mmu(struct kvm *kvm) > +{ > + kvm->arch.shadow_mmu_active = true; > +} > + I think there's no lock protecting both the write and the read side. Therefore this should be an smp_store_release, and all checks in patch 2 should be an smp_load_acquire. Also, the assignments to slot->arch.rmap in patch 4 (alloc_memslot_rmap) should be an rcu_assign_pointer, while __gfn_to_rmap must be changed like so: + struct kvm_rmap_head *head; ... - return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; + head = srcu_dereference(slot->arch.rmap[level - PG_LEVEL_4K], &kvm->srcu, + lockdep_is_held(&kvm->slots_arch_lock)); + return &head[idx]; Paolo