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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 0A2DEC2D0EC for ; Tue, 7 Apr 2020 21:28:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4A8F2072A for ; Tue, 7 Apr 2020 21:28:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="EcH2LrXb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726436AbgDGV2S (ORCPT ); Tue, 7 Apr 2020 17:28:18 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:50848 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726386AbgDGV2S (ORCPT ); Tue, 7 Apr 2020 17:28:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=dF5pQpdVBqNC0kSnylLZyPWPJXxXRLznWdsyFigAa+Y=; b=EcH2LrXbGkY/A0oFSOCNRu8Kzn Jm1L3B8w2Z0EJIp1E6FXqTJGekUCp/ghbnSAyfVRBBjan/Awl8/21Lfwj/nIyORskbTf1sSOFcZud Viil12cmJ+sFXFpXtS22jYZXLfyNjo18kIQh0BOV2LpsI0NNohRe0UpZaQ9kVJO5EJ/fcROu58KjZ XOD9UXnK1HSXIqXhb7u7Lf9lwNhiyEAfyFSLG0wBF5L/yd2bY0nLJ0Ac9wAJbdktKkmjjS6dG8Rtg UTdM6fuAZpK8buCxz7vmKIRKqZOglWpvEJd5/g0W5TXtXmJtSisb2P4mDRXgwuNbVxFs9rL6W6SqR Mul4V5hg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jLvlF-0002vH-0a; Tue, 07 Apr 2020 21:27:57 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id E13B89803E1; Tue, 7 Apr 2020 23:27:54 +0200 (CEST) Date: Tue, 7 Apr 2020 23:27:54 +0200 From: Peter Zijlstra To: Nadav Amit Cc: Thomas Gleixner , LKML , hch@infradead.org, Sean Christopherson , mingo , bp , hpa@zytor.com, x86 , "Kenneth R. Crudup" , Jessica Yu , Rasmus Villemoes , Paolo Bonzini , Fenghua Yu , Xiaoyao Li , Thomas Hellstrom , Tony Luck , Steven Rostedt , Greg Kroah-Hartman , jannh@google.com, keescook@chromium.org, David.Laight@aculab.com, Doug Covelli , mhiramat@kernel.org Subject: Re: [PATCH 4/4] x86,module: Detect CRn and DRn manipulation Message-ID: <20200407212754.GU2452@worktop.programming.kicks-ass.net> References: <20200407110236.930134290@infradead.org> <20200407111007.429362016@infradead.org> <10ABBCEE-A74D-4100-99D9-05B4C1758FF6@gmail.com> <20200407193853.GP2452@worktop.programming.kicks-ass.net> <90B32DAE-0BB5-4455-8F73-C43037695E7C@gmail.com> <20200407205042.GT2452@worktop.programming.kicks-ass.net> <96C2F23A-D6F4-4A04-82B6-284788C5D2CC@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <96C2F23A-D6F4-4A04-82B6-284788C5D2CC@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 07, 2020 at 02:22:11PM -0700, Nadav Amit wrote: > Anyhow, I do not think it is the only use-case which is not covered by your > patches (even considering CRs/DRs alone). For example, there is no kernel > function to turn on CR4.VMXE, which is required to run hypervisors on x86. That needs an exported function; there is no way we'll allow random writes to CR4, there's too much dodgy stuff in there.