Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753879AbbGWSB5 (ORCPT ); Thu, 23 Jul 2015 14:01:57 -0400 Received: from mail-lb0-f176.google.com ([209.85.217.176]:33290 "EHLO mail-lb0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753553AbbGWSBz (ORCPT ); Thu, 23 Jul 2015 14:01:55 -0400 MIME-Version: 1.0 In-Reply-To: References: <20150723115638.0b5dec78@gandalf.local.home> From: Andy Lutomirski Date: Thu, 23 Jul 2015 11:01:34 -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: 1597 Lines: 36 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. --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/