Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751573AbaLQExF (ORCPT ); Tue, 16 Dec 2014 23:53:05 -0500 Received: from cantor2.suse.de ([195.135.220.15]:39214 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbaLQExD (ORCPT ); Tue, 16 Dec 2014 23:53:03 -0500 Message-ID: <54910C2B.3000805@suse.com> Date: Wed, 17 Dec 2014 05:52:59 +0100 From: Juergen Gross User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: "H. Peter Anvin" , x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, linux-kernel@vger.kernel.org, akataria@vmware.com, jongman.heo@samsung.com Subject: Re: [PATCH] x86: don't rely on VMWare emulating PAT MSR correctly References: <1418723914-9736-1-git-send-email-jgross@suse.com> <54906212.2010102@zytor.com> In-Reply-To: <54906212.2010102@zytor.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/16/2014 05:47 PM, H. Peter Anvin wrote: > On 12/16/2014 01:58 AM, Juergen Gross wrote: >> VMWare seems not to emulate the PAT MSR correctly: reaeding >> MSR_IA32_CR_PAT returns 0 even after writing another value to it. >> >> Detect this bug and don't use the read value if it is 0. >> >> Commit bd809af16e3ab1f8d55b3e2928c47c67e2a865d2 ("x86: Enable PAT to >> use cache mode translation tables") triggers this VMWare bug when the >> kernel is booted as a VMWare guest. >> >> Reported-by: Jongman Heo >> Signed-off-by: Juergen Gross >> Tested-by: Jongman Heo > > I presume cachability control is irrelevant for a VMware guest? I'm > wondering if it would be better to just plain ignore the failure rather > than disabling PAT. I'd rather disable PAT as this seems to be like a PAT erratum. In case you want to keep PAT active I can redo the patch to not rely on the read MSR value in the non-Xen case (under Xen reading the MSR is the only way to obtain the correct settings). Juergen -- 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/