From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756163AbZHYTxB (ORCPT ); Tue, 25 Aug 2009 15:53:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756085AbZHYTxB (ORCPT ); Tue, 25 Aug 2009 15:53:01 -0400 Received: from claw.goop.org ([74.207.240.146]:49461 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755524AbZHYTxA (ORCPT ); Tue, 25 Aug 2009 15:53:00 -0400 Message-ID: <4A94411E.708@goop.org> Date: Tue, 25 Aug 2009 12:53:02 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Lightning/1.0pre Thunderbird/3.0b3 MIME-Version: 1.0 To: Pekka Enberg CC: mingo@elte.hu, linux-kernel@vger.kernel.org, Arnd Hannemann , Brian Gerst Subject: Re: [PATCH] x86: Execute WP test after interrupts are enabled References: <1251227779-24347-1-git-send-email-penberg@cs.helsinki.fi> <4A943CBD.60808@goop.org> <1251229085.25686.2.camel@penberg-laptop> In-Reply-To: <1251229085.25686.2.camel@penberg-laptop> X-Enigmail-Version: 0.97a Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/25/09 12:38, Pekka Enberg wrote: > On Tue, 2009-08-25 at 12:34 -0700, Jeremy Fitzhardinge wrote: > >> I don't think this is the real fix, and it seems a bit ugly. I'm OK >> with it as a workaround, but I think it will end up getting reverted if >> applied. >> > Yeah, I'm fine with that. It's just that we're really late in the > release cycle now so I'd like to keep the fix as simple as possible. Yeah, that's fine, but I think something like this would be simpler. Arnd, could you test it please? From: Jeremy Fitzhardinge Date: Tue, 25 Aug 2009 12:47:17 -0700 Subject: [PATCH] xen: suppress WP test Xen always runs on CPUs which properly support WP enforcement in privileged mode, so there's no need to test for it. This also works around a crash reported by Arnd Hannemann, though I think its just a band-aid for that case. Reported-by: Arnd Hannemann Signed-off-by: Jeremy Fitzhardinge Cc: Pekka Enberg diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 16d0d70..e5b903b 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1069,6 +1069,7 @@ asmlinkage void __init xen_start_kernel(void) /* set up basic CPUID stuff */ cpu_detect(&new_cpu_data); new_cpu_data.hard_math = 1; + new_cpu_data.wp_works_ok = 1; new_cpu_data.x86_capability[0] = cpuid_edx(1); #endif > Do you think the real bug lies in Xen or...? > I'm unsure. If handling a trap ends up enabling interrupts for some reason, then things would break horribly all over the place, so it would have to be something a bit more subtle. I'm looking into it. J