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 D426AC433EF for ; Thu, 14 Apr 2022 09:09:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238109AbiDNJLY (ORCPT ); Thu, 14 Apr 2022 05:11:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241565AbiDNJLX (ORCPT ); Thu, 14 Apr 2022 05:11:23 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8AC7F6E574 for ; Thu, 14 Apr 2022 02:08:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649927337; 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=EXK01xwL5FfymBT2O/wpbjGm/1sDlFHcoIHw2SavFDU=; b=B06tffjLZSX1XnvvZA+ozn+tQWpM5Jcmyiag3mzobVOeiWdedUkdctcnhe7+gVyeOmUOu9 9Om/KHnT0XS9r1aKaXAkhMrjwh1t2rwVyp86Vh3lHmY+jBA5oxN8KCJ71kvAjnUShYBMJH aqeHiq6eWy3YJYgOp7A4MB3yLA9fQ3E= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-439-YDOMtDKaOLy8rMGP0kxKCQ-1; Thu, 14 Apr 2022 05:08:48 -0400 X-MC-Unique: YDOMtDKaOLy8rMGP0kxKCQ-1 Received: by mail-wm1-f69.google.com with SMTP id i66-20020a1c3b45000000b0038eab4e0feaso2129013wma.9 for ; Thu, 14 Apr 2022 02:08:48 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=EXK01xwL5FfymBT2O/wpbjGm/1sDlFHcoIHw2SavFDU=; b=jdV4m7HAgSiyC2kf1FPVRPdDGXG8LBXg8JBAtnuKataN9yXUNOuGwKUGowrAFh/6fD hFJw38CzwY8AwgF8y3nxsHd+zMamFpo45XLxcl1tWUo48NMPw7Jv7sN/P5G91c3vndcU 1AKxN/lrCxdXKF3agmDmCdqhiWPsHqdgrC50/wGpg/aknFgP9DckPEQa2TMEw01ABexk STF6GMGTyyGsZxYrD1dhGfXNwdi0xvF72TNY7VJ8RWM6irLNL82y80x2keKh7t6MGThk BrBg1kdK14PgodkcAE29ClzMnZIWOjvZRH5vNU6tHKyJM3gnEnf4WpHv7co0gi2hn3D5 3Pew== X-Gm-Message-State: AOAM533DNKXjYTc95SIWImM+w3TFjuXjoaIWv8U0GJU6WgqRlffHiBZ+ JePlxiIi/EEAoQ2+ALM1Ym4ZUa88SXyrHnW5iWcH2P8ixFXWaN52s2UMLVQXcGZ5ZEqTBQ3wmCx nItSDJmpTBziVNH8QMCXD X-Received: by 2002:a5d:64a5:0:b0:205:8e66:e9b1 with SMTP id m5-20020a5d64a5000000b002058e66e9b1mr1312050wrp.464.1649927327730; Thu, 14 Apr 2022 02:08:47 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwAXM3iNNx7LZYO7MKlv+Z8ZcSXxb0BvT2R6br6VU+ZZLHt08JHqpN2CnaubzNSWxNIqo5rdQ== X-Received: by 2002:a5d:64a5:0:b0:205:8e66:e9b1 with SMTP id m5-20020a5d64a5000000b002058e66e9b1mr1312028wrp.464.1649927327531; Thu, 14 Apr 2022 02:08:47 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id r4-20020a05600c35c400b0038cbd8c41e9sm4947976wmq.12.2022.04.14.02.08.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Apr 2022 02:08:46 -0700 (PDT) Message-ID: <683974e7-5801-e289-8fa4-c8a8d21ec1b2@redhat.com> Date: Thu, 14 Apr 2022 11:08:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [RFC PATCH V3 3/4] KVM: X86: Alloc role.pae_root shadow page Content-Language: en-US To: Lai Jiangshan , Sean Christopherson Cc: LKML , kvm@vger.kernel.org, Lai Jiangshan , Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , X86 ML , "H. Peter Anvin" , linux-doc@vger.kernel.org References: <20220330132152.4568-1-jiangshanlai@gmail.com> <20220330132152.4568-4-jiangshanlai@gmail.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 4/14/22 11:07, Lai Jiangshan wrote: >> I don't think this will work for shadow paging. CR3 only has to be 32-byte aligned >> for PAE paging. Unless I'm missing something subtle in the code, KVM will incorrectly >> reuse a pae_root if the guest puts multiple PAE CR3s on a single page because KVM's >> gfn calculation will drop bits 11:5. > > I forgot about it. Isn't the pae_root always rebuilt by if (!tdp_enabled && memcmp(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs))) kvm_mmu_free_roots(vcpu->kvm, mmu, KVM_MMU_ROOT_CURRENT); in load_pdptrs? I think reuse cannot happen. Paolo