From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751977AbdK0VPA (ORCPT ); Mon, 27 Nov 2017 16:15:00 -0500 Received: from mga09.intel.com ([134.134.136.24]:61412 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751501AbdK0VO7 (ORCPT ); Mon, 27 Nov 2017 16:14:59 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,465,1505804400"; d="scan'208";a="10259172" Subject: Re: [PATCH 23/43] x86/mm/kaiser: Introduce user-mapped per-cpu areas To: Borislav Petkov , Ingo Molnar References: <20171124172411.19476-1-mingo@kernel.org> <20171124172411.19476-24-mingo@kernel.org> <20171126174149.45jxcnsetodm32xl@pd.tnic> Cc: linux-kernel@vger.kernel.org, Andy Lutomirski , Thomas Gleixner , "H . Peter Anvin" , Peter Zijlstra , Linus Torvalds From: Dave Hansen Message-ID: <87e94437-c70c-dd0e-c1ba-001e4492c17a@linux.intel.com> Date: Mon, 27 Nov 2017 13:14:57 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171126174149.45jxcnsetodm32xl@pd.tnic> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/26/2017 09:41 AM, Borislav Petkov wrote: >> The KAISER approach keeps two copies of the page tables: one for running >> in the kernel and one for running userspace. But, there are a few >> structures that are needed for switching in and out of the kernel and >> a good subset of *those* are per-cpu data. >> >> This patch creates a new kind of per-cpu data that is mapped and > Never say "This patch" in the commit message of a patch. It is > tautologically useless. Look at any academic paper's abstract. They almost always describe the problem and the state of the art, and then start to describe the paper's content. It's entirely normal to say "this paper" to help differentiate these things. Patches can and should be the same. We should not litter the text with "this patch does this", "this patch does that", but we should not outlaw it entirely. IOW, you can't just blindly say, not to do it.