Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933906AbdCJLem (ORCPT ); Fri, 10 Mar 2017 06:34:42 -0500 Received: from smtp46.i.mail.ru ([94.100.177.106]:57990 "EHLO smtp46.i.mail.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933734AbdCJLec (ORCPT ); Fri, 10 Mar 2017 06:34:32 -0500 Subject: Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention To: Andy Lutomirski 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> Cc: Ricardo Neri , 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 From: Stas Sergeev Message-ID: <63231222-5b42-c8c9-02f0-0afbe702d8b5@list.ru> Date: Fri, 10 Mar 2017 14:33:53 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Authentication-Results: smtp46.i.mail.ru; auth=pass smtp.auth=stsp@list.ru smtp.mailfrom=stsp@list.ru X-7FA49CB5: 0D63561A33F958A54370A0D84A24018D4B75BAE21DF15A3649D0934BFA5585B59F18ECD7E95F35E929AFE063DF4C541C9D7C975D552847A4DFEFDEAFD9636C500BF2EBBBDD9D6B0FAEAACC865B01FC22 X-Mailru-Sender: F1845AB6CCC9920DF7838D61D4D05C421046908D5781F18726268B4A8A6F9CD8E23BA72BC693BAAB1653177920737CA72999BEE114A20FF4278B2D54D4112F244F0A872F021F905956A8FB0C6EBA5FCCEAB4BC95F72C04283CDA0F3B3F5B9367 X-Mras: OK Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1939 Lines: 40 10.03.2017 05:39, Andy Lutomirski пишет: > On Thu, Mar 9, 2017 at 2:10 PM, Stas Sergeev wrote: >> 09.03.2017 04:15, Ricardo Neri пишет: >> >>> On Wed, 2017-03-08 at 08:46 -0800, Andy Lutomirski wrote: >>>> On Wed, Mar 8, 2017 at 8:29 AM, Stas Sergeev wrote: >>>>> 08.03.2017 19:06, Andy Lutomirski пишет: >>>>>> On Wed, Mar 8, 2017 at 6:08 AM, Stas Sergeev wrote: >>>>>>> 08.03.2017 03:32, Ricardo Neri пишет: >>>>>>>> These are the instructions covered by UMIP: >>>>>>>> * SGDT - Store Global Descriptor Table >>>>>>>> * SIDT - Store Interrupt Descriptor Table >>>>>>>> * SLDT - Store Local Descriptor Table >>>>>>>> * SMSW - Store Machine Status Word >>>>>>>> * STR - Store Task Register >>>>>>>> >>>>>>>> This patchset initially treated tasks running in virtual-8086 >>>> mode as a >>>>>>>> special case. However, I received clarification that DOSEMU[8] >>>> does not >>>>>>>> support applications that use these instructions. >>>>>> Can you remind me what was special about it? It looks like you >>>> still >>>>>> emulate them in v8086 mode. >>>>> Indeed, sorry, I meant prot mode here. :) >>>>> So I wonder what was cited to be special about v86. >>> Initially my patches disabled UMIP on virtual-8086 instructions, without >>> regards of protected mode (i.e., UMIP was always enabled). I didn't have >>> emulation at the time. Then, I added emulation code that now covers >>> protected and virtual-8086 modes. I guess it is not special anymore. >> But isn't SLDT&friends just throw UD in v86? >> How does UMIP affect this? How does your patch affect >> this? > Er, right. Ricardo, your code may need fixing. But don't you have a > test case for this? Why would you need one? Or do you really want to allow these instructions in v86 by the means of emulation? If so - this wasn't clearly stated in the patch description, neither it was properly discussed, it seems.