Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754952AbdC3FON (ORCPT ); Thu, 30 Mar 2017 01:14:13 -0400 Received: from mga09.intel.com ([134.134.136.24]:8067 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754735AbdC3FOL (ORCPT ); Thu, 30 Mar 2017 01:14:11 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.36,245,1486454400"; d="scan'208";a="66751895" Message-ID: <1490850848.2647.28.camel@ranerica-desktop> Subject: Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention From: Ricardo Neri To: Stas Sergeev Cc: Andy Lutomirski , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Borislav Petkov , Peter Zijlstra , Andrew Morton , Brian Gerst , Chris Metcalf , Dave Hansen , Paolo Bonzini , Liang Z Li , Masami Hiramatsu , Huang Rui , Jiri Slaby , Jonathan Corbet , "Michael S. Tsirkin" , Paul Gortmaker , Vlastimil Babka , Chen Yucong , Alexandre Julliard , Fenghua Yu , "Ravi V. Shankar" , Shuah Khan , "linux-kernel@vger.kernel.org" , X86 ML , linux-msdos@vger.kernel.org, wine-devel@winehq.org Date: Wed, 29 Mar 2017 22:14:08 -0700 In-Reply-To: <2a9c7bfd-e85c-2673-d3b5-906fe7dd8db4@list.ru> References: <20170308003254.27833-1-ricardo.neri-calderon@linux.intel.com> <79ba0fff-4c01-2bfa-06cb-5cfc98dd710c@list.ru> <997ba581-ecfa-b773-a48e-85b92a439836@list.ru> <1489022122.131264.33.camel@ranerica-desktop> <63231222-5b42-c8c9-02f0-0afbe702d8b5@list.ru> <1489190396.131264.47.camel@ranerica-desktop> <6331deea-e9b0-fcfe-b75d-8100f37a615a@list.ru> <1490658399.2647.14.camel@ranerica-desktop> <1490762284.2647.24.camel@ranerica-desktop> <2a9c7bfd-e85c-2673-d3b5-906fe7dd8db4@list.ru> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2128 Lines: 53 On Wed, 2017-03-29 at 23:55 +0300, Stas Sergeev wrote: > 29.03.2017 07:38, Ricardo Neri пишет: > >> Probably you could also remove > >> the sldt and str emulation for protected mode, because, > >> as I understand from this thread, wine does not > >> need those. > > I see. I would lean on keeping the emulation because I already > > implemented it :), for completeness, and because it is performed in a > > single switch. The bulk of the emulation code deals with operands. > But this is not for free. > As Andy said, you will then need a syscall and > a feature mask to be able to disable this emulation. > And AFAIK you haven't implemented that yet, so > there is something to consider. Right, I see your point. > >>>> You know the wine's > >>>> requirements now - they are very small. And > >>>> dosemu doesn't need anything at all but smsw. > >>>> And even smsw is very rare. > >>> But emulation is still needed for SMSW, right? > >> Likely so. > >> If you want, I can enable the logging of this command > >> and see if it is used by some of the DOS programs I have. > > It would be great if you could do that, if you don't mind. > OK, scheduled to the week-end. > I'll let you know. Thanks! > > >> But at least dosemu implements it, so probably it is needed. > > Right. > > > >> Of course if it is used by one of 100 DOS progs, then there > >> is an option to just add its support to dosemu2 and pretend > >> the compatibility problems did not exist. :) > > Do you mean relaying the GP fault to dosemu instead of trapping it and > > emulating it in the kernel? > Yes, that would be optimal if this does not severely break > the current setups. If we can find out that smsw is not in > the real use, we can probably do exactly that. > But other > instructions are not in real use in v86 for sure, so I > wouldn't be adding the explicit test-cases to the kernel > that will make you depend on some particular behaviour > that no one may need. > My objection was that we shouldn't > write tests before we know exactly how we want this to work. OK, if only SMSW is used then I'll keep the emulation for SMSW only.