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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 42A56C31E51 for ; Tue, 18 Jun 2019 04:09:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 178202085A for ; Tue, 18 Jun 2019 04:09:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="PJ3Iztta" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726171AbfFREJM (ORCPT ); Tue, 18 Jun 2019 00:09:12 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:45057 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725826AbfFREJM (ORCPT ); Tue, 18 Jun 2019 00:09:12 -0400 Received: by mail-pg1-f194.google.com with SMTP id s21so6898936pga.12 for ; Mon, 17 Jun 2019 21:09:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=sxNxwbhlDFusqMdbSWcqqNQNWyvayYOF2m7mBoRJYf4=; b=PJ3IzttaXZ9ZP6m+bK5SbxOo0k0L5mVCRCs/HEeYWoAP0fd2T6fE9j4DdYSjPn2Igq RLpzTaKQhrkUsMJh5TuCLDkONT2MOhoIWpqkbpil9eGw1hDnCZubrZyH48l+5MMjOdqS yXpWOfaHaY7lZ9z3iBYrjt1cyFA4aZtBxzOko= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=sxNxwbhlDFusqMdbSWcqqNQNWyvayYOF2m7mBoRJYf4=; b=DvuCRSp+n4XEcqvJp0WN2EJep5YrgXeEpRmR+jCg/tKWwmGbgd763SG/bUZrvSvhNk 13337MantNH6e+3lCgh/lrDKDj37VaQI/q8c2g6Vb2aHsWH4vJGSokLIejqSVeYqtYer 9QM37hGLWn6oUOm6zMPUl/TulCi9V3hLbmtySELBAzNa0XeMqfqAsT0idCeHwEUBaC9h BE2O9HZasFiI2srtO+RAczuj/6bIvowZhvPrSaaCMV9r8p27rOJGnVkwih/dc9BOMome tT8QOo94bumeZXJTHblHsbSXgNp20XS6FMSQmSSwkBRSqZhR2L9Hye/YiMvhMQhTkNgV xvzw== X-Gm-Message-State: APjAAAVXIEodqljypNUwrbAnPsHbZInzm6D1PV+XGOJvL8LommwtsEEi k8qhkyaQnGTbGu6gyTjuHc5nAQ== X-Google-Smtp-Source: APXvYqwF3JzZ+qH5xB0+Z14HJGeTdacZf7tH8hhFgeuBeekzs8qvdSqYK7/b6J/UDBy3h0/S5YR4UQ== X-Received: by 2002:aa7:957c:: with SMTP id x28mr1396954pfq.42.1560830951687; Mon, 17 Jun 2019 21:09:11 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id v138sm20195688pfc.15.2019.06.17.21.09.10 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 17 Jun 2019 21:09:10 -0700 (PDT) Date: Mon, 17 Jun 2019 21:09:09 -0700 From: Kees Cook To: Thomas Gleixner Cc: Linus Torvalds , x86@kernel.org, Peter Zijlstra , Dave Hansen , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] x86/asm: Pin sensitive CR4 bits Message-ID: <201906172050.AA52A49E9@keescook> References: <20190604234422.29391-1-keescook@chromium.org> <20190604234422.29391-2-keescook@chromium.org> <201906142012.C18377C5@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 17, 2019 at 12:26:01AM +0200, Thomas Gleixner wrote: > Nah. The straight forward approach is to do right when the secondary CPU > comes into life, before it does any cr4 write (except for the code in > entry_64.S), something like the below. Okay, will do; thanks! :) I'll respin things and get it tested. -- Kees Cook