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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 E8AE8C433E0 for ; Fri, 19 Jun 2020 13:44:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3E3D208C7 for ; Fri, 19 Jun 2020 13:44:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="rYRKZmmp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732776AbgFSNog (ORCPT ); Fri, 19 Jun 2020 09:44:36 -0400 Received: from mail.skyhub.de ([5.9.137.197]:54236 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731806AbgFSNog (ORCPT ); Fri, 19 Jun 2020 09:44:36 -0400 Received: from zn.tnic (p200300ec2f0bac004d57d24caa4a0e33.dip0.t-ipconnect.de [IPv6:2003:ec:2f0b:ac00:4d57:d24c:aa4a:e33]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id C47BB1EC03D0; Fri, 19 Jun 2020 15:44:34 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1592574274; 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:in-reply-to:in-reply-to: references:references; bh=Jw9EeswGVAhRId5Z/cmoaOU/4YK2HM29pcIB4hBn/pg=; b=rYRKZmmpr9nuGcCzk+JgYOV0qgBhlUx5hgV+Cd3zH36cFiUm2unC+WhzcRnIpUJYkdJDvI 7rieju2IeWv5m3RIBAndZQvzy9eNwYM4sn4VlHQkd5fISffZAqOIRKuQFfVQnv8u3lIhPa fLhN0aHPID/6C/9VlrgjBJhn8Apz2Zc= Date: Fri, 19 Jun 2020 15:44:32 +0200 From: Borislav Petkov To: Richard Hughes Cc: Daniel Gutson , Dave Hansen , Thomas Gleixner , Ingo Molnar , x86@kernel.org, "H. Peter Anvin" , Arnd Bergmann , Greg Kroah-Hartman , Peter Zijlstra , "David S. Miller" , Rob Herring , Tony Luck , Rahul Tanwar , Xiaoyao Li , Sean Christopherson , Dave Hansen , linux-kernel Subject: Re: [PATCH] Ability to read the MKTME status from userspace Message-ID: <20200619134432.GE32683@zn.tnic> References: <20200618210215.23602-1-daniel.gutson@eclypsium.com> <589c89ae-620e-36f8-2be5-4afc727c2911@intel.com> <20200618220139.GH27951@zn.tnic> <20200619074053.GA32683@zn.tnic> <20200619132243.GC32683@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 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 Fri, Jun 19, 2020 at 02:31:11PM +0100, Richard Hughes wrote: > 1. that the CPU supports TME (->cpuid, already done) > 2. that the platform has not disabled TME in some way Yes, this is what I'm proposing with clearing the flag in /proc/cpuinfo. The needed information is there: 1. TME in CPUID 2. TME *not* in /proc/cpuinfo which means the platform doesn't support it. If we are going to export a list of features which the OS kernel/platform has enabled - and this means a contract between kernel and userspace - then this should not be a misc driver which gets loaded as a module but builtin, maybe a proper sysfs layout similar to /sys/devices/system/cpu/vulnerabilities which userspace can use. Along with proper ABI definition, design, documentation and all that belongs to a proper interface with userspace. Because once userspace uses it, it is practically cast in stone. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette