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=-7.3 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 0A9C2C43332 for ; Fri, 5 Mar 2021 17:53:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E060E65073 for ; Fri, 5 Mar 2021 17:53:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229759AbhCERxK (ORCPT ); Fri, 5 Mar 2021 12:53:10 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:58992 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229788AbhCERwu (ORCPT ); Fri, 5 Mar 2021 12:52:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614966769; 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=iwTUMCcDk00xNetkHK1hGOt7MdI+EmpsAycWvHQG5xE=; b=R7ZxebugkABt1ONG23MHUByX6t7Z3jAwhijo/0eI5p+5EWoTxettUU22Q0Zd3DAbGFTRke H5sxuc6Gw0Imec+fJtFjnSuyHI2bzPinJyzb1ePosQRoJ1LvIzS/8AaE8bNMvfmOxlrT4/ oth9K38dhlmVtwLMFoBRGzQs3Y+yZ6k= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-562-dALTlOhbPu6EaeAOMPWziQ-1; Fri, 05 Mar 2021 12:52:48 -0500 X-MC-Unique: dALTlOhbPu6EaeAOMPWziQ-1 Received: by mail-wr1-f71.google.com with SMTP id i5so1368950wrp.8 for ; Fri, 05 Mar 2021 09:52:47 -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=iwTUMCcDk00xNetkHK1hGOt7MdI+EmpsAycWvHQG5xE=; b=WccyLrxoQ5LpBNCRkeAEQ7IcpFl0ahhsqALcVBbkItYAJYx4qtoWGOedzdjHo7Ibq4 mbSGzxmAALcGPoHyhpJiM4AEJ37IhJWZ2cq/6ZP6UWisoG1Tamh/GKzkecBLSR9akuJL BsFiQFJ4fh1c1XZBAnMoByRRqZWW5GEZeQnn5eMoqZUcR43RqPZO23kGcHn58+T6VoG+ XmTspOrrcPUTAw9P1IlEpGfJTfDcYdDF4QTvLBQS2hlK43FlYEjdAvVyaWzmRniIkWfb eUZbXYeVzx05801RXvuHjbP/Oc/FYPUWf8QPFVV4pqXciaPp8nspKmmHe6ugeVPcdvys NQrA== X-Gm-Message-State: AOAM530uaWUub8HDE4Ce3onFhGdcWPOaxHZ0lowW8+Jw+yS/EJDwuM2E svcCXKR2rjvckYi+Osu8KHiSwdOMpVY3IlQngf+o4QObKk3nf/JORyykX14QuMTizXeT5lv/zPS hTlUiWdBUMS9ZxuG6/dohvXF7 X-Received: by 2002:adf:e412:: with SMTP id g18mr10832927wrm.159.1614966766374; Fri, 05 Mar 2021 09:52:46 -0800 (PST) X-Google-Smtp-Source: ABdhPJztT0w4Di9/TF3GU88h8n5kTz6vIOB4/z08cfkSJ5CRd8Qk58FwubiiaShGjTbCmT7i5nN8EA== X-Received: by 2002:adf:e412:: with SMTP id g18mr10832908wrm.159.1614966766186; Fri, 05 Mar 2021 09:52:46 -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 c26sm5938195wrb.87.2021.03.05.09.52.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Mar 2021 09:52:45 -0800 (PST) Subject: Re: [PATCH v2 09/17] KVM: x86/mmu: Use '0' as the one and only value for an invalid PAE root To: Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ben Gardon , Brijesh Singh , Tom Lendacky References: <20210305011101.3597423-1-seanjc@google.com> <20210305011101.3597423-10-seanjc@google.com> From: Paolo Bonzini Message-ID: <63d2a610-f897-805c-23a7-488a65485f36@redhat.com> Date: Fri, 5 Mar 2021 18:52:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210305011101.3597423-10-seanjc@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 05/03/21 02:10, Sean Christopherson wrote: > Use '0' to denote an invalid pae_root instead of '0' or INVALID_PAGE. > Unlike root_hpa, the pae_roots hold permission bits and thus are > guaranteed to be non-zero. Having to deal with both values leads to > bugs, e.g. failing to set back to INVALID_PAGE, warning on the wrong > value, etc... I don't dispute this is a good idea, but it deserves one or more comments. Paolo