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 5DE0DC433EF for ; Wed, 8 Dec 2021 09:09:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230215AbhLHJNH (ORCPT ); Wed, 8 Dec 2021 04:13:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229604AbhLHJNG (ORCPT ); Wed, 8 Dec 2021 04:13:06 -0500 Received: from mail-ed1-x532.google.com (mail-ed1-x532.google.com [IPv6:2a00:1450:4864:20::532]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E738BC061746; Wed, 8 Dec 2021 01:09:34 -0800 (PST) Received: by mail-ed1-x532.google.com with SMTP id l25so5966315eda.11; Wed, 08 Dec 2021 01:09:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=yxJcUg9sr80nOyHJimTgCrmoTuePLh38op6h19juAN8=; b=KxmeuubkIsid0/Zjzzn7drJ0L1h6+WV6DWVWUMk2BiOWy13ruchzwLqm2oijcsPVpE to/VbHRF1yMHhG0FiuJ7/OmPiPOWlYCMZhrzS0Di/7rcQD8JyNMrJwW6Lwqekk89pZ9P iedFxwe+A1CFiNuA5/kS0fGrG/XIeKNP9asAPuF++KgVaQob2qhtIWMh0BYlf2+pUDmr JxOFSPgmF2stkrxY19oUSfRuF7j55Jnl622/QXszvGBMuxxvNR+/MRZ72wJnYUvUAlUI 1gWPnqKldj6gN+JE8YwMRZc8cGOLV+O9s0MIo9wl0Jw6gazdgrW0VXLGvWS0otivgPld TDpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:message-id:date:mime-version:user-agent :subject:content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=yxJcUg9sr80nOyHJimTgCrmoTuePLh38op6h19juAN8=; b=nvb39WSuz4iJcUtiFLcX+FuI3b6iOpehyUQTfCDQ6sztDR/aqJ8fjbF6j/vRe2jEWA hJ+bttECRE46yCcpKmW29qzZw8MCvFe6BP9CqoVwCuXxKLutt8ar3gz28D2cAqdbp06n 8qFT5nObEXMUiqmX1QSstmyv1HXmXS5DB7XPZ69vO8QX3TIHJXk48DumIP+YXi4DEOP8 zyZWJ6cqvIjyjNVZqhMHTOTF5pjA1t+CqdiymV/cVwKToNNH1sSLHmOCKW1wEl4IkEwl gzAnZwF2Jb88CHsbJEdNxgAZYu5H+QHDhzt2DjQGIY/00G4Rn/AI+PJ7DDASsiYj9QRe gXxw== X-Gm-Message-State: AOAM533BCPxnR4FwPhqFawqX7Tbp/8PdsrcXCrGhwEOcbvKmbfy6jvoW mZ4dRzHZ6aKbvwio3IjhO2o= X-Google-Smtp-Source: ABdhPJxlOWCIQm+Jvdx6A/CtmDxo8HbH6QmDLTJeN+1HhkhDhp+9MKTNku5GvFmdsWYRXrANcF5d9g== X-Received: by 2002:a17:906:6a18:: with SMTP id qw24mr6143614ejc.118.1638954573547; Wed, 08 Dec 2021 01:09:33 -0800 (PST) Received: from ?IPV6:2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e? ([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.googlemail.com with ESMTPSA id t5sm1632550edd.68.2021.12.08.01.09.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Dec 2021 01:09:33 -0800 (PST) Sender: Paolo Bonzini Message-ID: <60743c95-f9aa-a7c6-1709-39c70e224321@redhat.com> Date: Wed, 8 Dec 2021 10:09:30 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH 16/15] KVM: X86: Update mmu->pdptrs only when it is changed Content-Language: en-US To: Sean Christopherson , Lai Jiangshan Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Lai Jiangshan , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" References: <20211108124407.12187-1-jiangshanlai@gmail.com> <20211111144527.88852-1-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-kernel@vger.kernel.org On 12/8/21 00:43, Sean Christopherson wrote: > what guarantees the that PDPTRs in the VMCS are sync'd with > mmu->pdptrs? I'm not saying they aren't, I just want the changelog > to prove that they are. If they aren't synced you should *already* have dirty VCPU_EXREG_PDPTR and pending KVM_REQ_LOAD_MMU_PGD, shouldn't you? As long as the caching invariants are respected, this patch is fairly safe, and if they aren't there are plenty of preexisting bugs anyway. Paolo > The next patch does add a fairly heavy unload of the current root for > !TDP, but that's a bug fix and should be ordered before any > optimizations anyways.