From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751729AbdGYXv6 (ORCPT ); Tue, 25 Jul 2017 19:51:58 -0400 Received: from mga11.intel.com ([192.55.52.93]:22719 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751402AbdGYXv5 (ORCPT ); Tue, 25 Jul 2017 19:51:57 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,413,1496127600"; d="scan'208";a="131220586" Message-ID: <1501026716.22603.52.camel@ranerica-desktop> Subject: Re: [PATCH v7 23/26] x86/traps: Fixup general protection faults caused by UMIP From: Ricardo Neri To: Borislav Petkov Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Andrew Morton , Brian Gerst , Chris Metcalf , Dave Hansen , Paolo Bonzini , Masami Hiramatsu , Huang Rui , Jiri Slaby , Jonathan Corbet , "Michael S. Tsirkin" , Paul Gortmaker , Vlastimil Babka , Chen Yucong , Alexandre Julliard , Stas Sergeev , Fenghua Yu , "Ravi V. Shankar" , Shuah Khan , linux-kernel@vger.kernel.org, x86@kernel.org, linux-msdos@vger.kernel.org, wine-devel@winehq.org, Tony Luck Date: Tue, 25 Jul 2017 16:51:56 -0700 In-Reply-To: <20170609130248.h63fmhzpyn7xkeke@pd.tnic> References: <20170505181724.55000-1-ricardo.neri-calderon@linux.intel.com> <20170505181724.55000-24-ricardo.neri-calderon@linux.intel.com> <20170609130248.h63fmhzpyn7xkeke@pd.tnic> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I am sorry Boris, I also missed this feedback. On Fri, 2017-06-09 at 15:02 +0200, Borislav Petkov wrote: > On Fri, May 05, 2017 at 11:17:21AM -0700, Ricardo Neri wrote: > > If the User-Mode Instruction Prevention CPU feature is available and > > enabled, a general protection fault will be issued if the instructions > > sgdt, sldt, sidt, str or smsw are executed from user-mode context > > (CPL > 0). If the fault was caused by any of the instructions protected > > by UMIP, fixup_umip_exception will emulate dummy results for these > > Please end function names with parentheses. I have audited my commit messages to remove all instances of this error. > > > instructions. If emulation is successful, the result is passed to the > > user space program and no SIGSEGV signal is emitted. > > > > Please note that fixup_umip_exception also caters for the case when > > the fault originated while running in virtual-8086 mode. > > > > Cc: Andy Lutomirski > > Cc: Andrew Morton > > Cc: H. Peter Anvin > > Cc: Borislav Petkov > > Cc: Brian Gerst > > Cc: Chen Yucong > > Cc: Chris Metcalf > > Cc: Dave Hansen > > Cc: Fenghua Yu > > Cc: Huang Rui > > Cc: Jiri Slaby > > Cc: Jonathan Corbet > > Cc: Michael S. Tsirkin > > Cc: Paul Gortmaker > > Cc: Peter Zijlstra > > Cc: Ravi V. Shankar > > Cc: Shuah Khan > > Cc: Vlastimil Babka > > Cc: Tony Luck > > Cc: Paolo Bonzini > > Cc: Liang Z. Li > > Cc: Alexandre Julliard > > Cc: Stas Sergeev > > Cc: x86@kernel.org > > Cc: linux-msdos@vger.kernel.org > > Reviewed-by: Andy Lutomirski > > Signed-off-by: Ricardo Neri > > --- > > arch/x86/kernel/traps.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > > index 3995d3a..cec548d 100644 > > --- a/arch/x86/kernel/traps.c > > +++ b/arch/x86/kernel/traps.c > > @@ -65,6 +65,7 @@ > > #include > > #include > > #include > > +#include > > > > #ifdef CONFIG_X86_64 > > #include > > @@ -526,6 +527,9 @@ do_general_protection(struct pt_regs *regs, long error_code) > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); > > cond_local_irq_enable(regs); > > > > Almost definitely: > > if (static_cpu_has(X86_FEATURE_UMIP)) { > if (... I will make this update. > > > + if (user_mode(regs) && fixup_umip_exception(regs)) > > + return; > > We don't want to punish !UMIP machines. I will add this check. Thanks and BR, Ricardo