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 ECAB2C433EF for ; Wed, 8 Dec 2021 18:40:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239158AbhLHSoS (ORCPT ); Wed, 8 Dec 2021 13:44:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230040AbhLHSoR (ORCPT ); Wed, 8 Dec 2021 13:44:17 -0500 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2A81C0617A2 for ; Wed, 8 Dec 2021 10:40:45 -0800 (PST) Received: by mail-pl1-x631.google.com with SMTP id n8so2122430plf.4 for ; Wed, 08 Dec 2021 10:40:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=2esW1PgwMW/uPgw9HwrxttsSErnSmH0L2IFPbegvGZ0=; b=JMOFGrTmIpVxHPJ19wMiBSNYvcNn4mkwdiP01+P4qAv6w5oI848W7a5nKo+HHiDamf CgyZySrRXpQx35cciVcOAxORaZROKTbyhnq+6dGXPeuaQ9G8lTZTcs/HqoYeQzXCeexR aC9M7oj8N1uyoTJ22SaBHVyL5KYIF8eEEza3rwrcm0tUVNfMiPP2T3MGPsbj1wRgZt7U yInbZBE080qCbZs6+hPqLbNUFvRWtbFpScL2EaazzzSdx7i0fnJJduDEOJ63fYHIBkTj 9yUVsVEvoODMCxiJ70Aa8yw9QZ5ML8PdSzvcy2YO1vi25xxf+y5wlWSsG9EhFMRNTiWO oeyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=2esW1PgwMW/uPgw9HwrxttsSErnSmH0L2IFPbegvGZ0=; b=2us1Y8QsHvhNfZIcejz0XMqw8JuEcyqqFg9cYc9/j14gv5BLw/HljgT9PrcV6P3jzx 3g6I7v7b9ULkiWZ742smoveFfr3Z7O0NTlrfRU2L/ibYn4RXh0Y1bWhgTITErLU9m7Tt PZDuUN7WTNzMf6hainTH7PYhXb0MMHgSoqGrxGfepHhpM6aQlBrFizlfRyL8xIXNCltN 5WwHiKymAaj2wPm2aI0qOSGbYPtxi2OqLSv8vuUTM1R6TIxKonbeG6c6e0bTpNRYEzIP VL9hULRHcnh1H0iHgwKENLYcbtwYGNR65OShEl5y1GJM3VIfZaYJgT7I+Mc7SXzCqn0H qDVg== X-Gm-Message-State: AOAM530lL2iPGaF5uRZrHC3t3LU6aypaJaD5mfwCQ1umzkgMYoqPuleD rPf+ED4bYGpIxLNznnNiXKtzGg== X-Google-Smtp-Source: ABdhPJzClCXWnuOKDKj88Rz4E8jDDb4uaV82hAB72j9+tDfCTT3P2Gq1tWJQXULxbEHjlyKhl7uk0Q== X-Received: by 2002:a17:902:e302:b0:141:af98:b5ea with SMTP id q2-20020a170902e30200b00141af98b5eamr60821172plc.53.1638988845033; Wed, 08 Dec 2021 10:40:45 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id r16sm3294860pgk.45.2021.12.08.10.40.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Dec 2021 10:40:44 -0800 (PST) Date: Wed, 8 Dec 2021 18:40:40 +0000 From: Sean Christopherson To: Li Yu Cc: pbonzini@redhat.com, Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , "Paul E. McKenney" , Andrew Morton , Peter Zijlstra , Lu Baolu , "Maciej W. Rozycki" , Muchun Song , Viresh Kumar , Robin Murphy , Randy Dunlap , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v3] KVM: x86/mmu: Warn on iTLB multi-hit for possible problems Message-ID: References: <20211020043131.1222542-1-liyu.yukiteru@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211020043131.1222542-1-liyu.yukiteru@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Oct 20, 2021, Li Yu wrote: > Warn for guest huge pages split if iTLB multi-hit bug is present > and CPU mitigations is enabled. > > Warn for possible CPU lockup if iTLB multi-hit bug is present but > CPU mitigations is disabled. > > Signed-off-by: Li Yu > --- Gah, my last reply in the previous version was offlist. I would like an answer to the below question before we complicate KVM just to log a message. On Wed, Oct 20, 2021 at 12:51 PM Sean Christopherson wrote: > > On Wed, Oct 20, 2021, Li Yu wrote: > > On 2021/10/20 00:23, Sean Christopherson wrote: > > I think it is necessary to log something when `nx_huge_pages` is `auto` or > > `off`, and the bug is present. > > Why is it necessary? Specifically, what action can be taken based on KVM logging > that can't reasonably be taken based on all the other information provided by the > kernel? We should teach userspace to go look at the vulnerabilites info, not to > scrape the kernel log.