Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753954AbbGWSdc (ORCPT ); Thu, 23 Jul 2015 14:33:32 -0400 Received: from mail-la0-f54.google.com ([209.85.215.54]:36491 "EHLO mail-la0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752899AbbGWSda (ORCPT ); Thu, 23 Jul 2015 14:33:30 -0400 MIME-Version: 1.0 In-Reply-To: References: <20150723115638.0b5dec78@gandalf.local.home> From: Andy Lutomirski Date: Thu, 23 Jul 2015 11:33:09 -0700 Message-ID: Subject: Re: [PATCH 1/5] x86/entry/32: Clean up enable_sep_cpu to prepare for 64-bit merge To: Brian Gerst 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: 1804 Lines: 42 On Thu, Jul 23, 2015 at 11:01 AM, Andy Lutomirski wrote: > On Thu, Jul 23, 2015 at 10:27 AM, Brian Gerst wrote: >> 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. > > I can make a v2 that gets rid of the _safe. > Ugh. wrmsrl_safe is a function but wrmsrl isn't. I'll fix that and send a v2. Gah, macros. --Andy -- 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/