Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754036AbbGWR1g (ORCPT ); Thu, 23 Jul 2015 13:27:36 -0400 Received: from mail-oi0-f50.google.com ([209.85.218.50]:33727 "EHLO mail-oi0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752577AbbGWR1d (ORCPT ); Thu, 23 Jul 2015 13:27:33 -0400 MIME-Version: 1.0 In-Reply-To: References: <20150723115638.0b5dec78@gandalf.local.home> Date: Thu, 23 Jul 2015 13:27:32 -0400 Message-ID: Subject: Re: [PATCH 1/5] x86/entry/32: Clean up enable_sep_cpu to prepare for 64-bit merge From: Brian Gerst To: Andy Lutomirski Cc: Steven Rostedt , Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , Willy Tarreau , Borislav Petkov , Thomas Gleixner , Peter Zijlstra , Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1457 Lines: 34 On Thu, Jul 23, 2015 at 12:02 PM, Andy Lutomirski wrote: > On Thu, Jul 23, 2015 at 8:56 AM, Steven Rostedt wrote: >> On Thu, 23 Jul 2015 08:31:39 -0700 >> Andy Lutomirski wrote: >> >>> Switch from wrmsr to wrmsrl_safe to prepare to merge the 32-bit and >>> 64-bit code, and use __KERNEL_CS explicitly to initialize >>> MSR_IA32_SYSENTER_CS. While we're at it, tweak the whitespace a >>> bit. >> >> Saying "prepare to merge the 32-bit and 64-bit" isn't that informative >> to why this patch is needed. Can you please describe in the change log >> what can fault with the wrmsr call, when we do the merge? > > Oh... > > Nothing can fault in the wrmsr as far as I know, but maybe there's a > CPU out there that advertises SEP but doesn't have the MSRs. > > Ingo, Thomas, want a v2 that explains that the wrmsr_safe is there for > consistency but that I don't know why 32bit does it? Another option > would be to remove the _safe from the 32-bit version. There is an erratum with SEP being advertised but not available on early P6 models, but we already check for that in the cpu setup code. There shouldn't be a problem with a fault. -- Brian Gerst -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/