From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759058Ab0EXXM1 (ORCPT ); Mon, 24 May 2010 19:12:27 -0400 Received: from kroah.org ([198.145.64.141]:36467 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759008Ab0EXXJb (ORCPT ); Mon, 24 May 2010 19:09:31 -0400 X-Mailbox-Line: From gregkh@clark.site Mon May 24 16:03:51 2010 Message-Id: <20100524230351.224349120@clark.site> User-Agent: quilt/0.48-8.10 Date: Mon, 24 May 2010 15:59:53 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andreas Herrmann , "H. Peter Anvin" Subject: [21/34] x86, amd: Check X86_FEATURE_OSVW bit before accessing OSVW MSRs In-Reply-To: <20100524230418.GA12770@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.34-stable review patch. If anyone has any objections, please let us know. ------------------ From: Andreas Herrmann commit f01487119dda3d9f58c9729c7361ecc50a61c188 upstream. If host CPU is exposed to a guest the OSVW MSRs are not guaranteed to be present and a GP fault occurs. Thus checking the feature flag is essential. Signed-off-by: Andreas Herrmann LKML-Reference: <20100427101348.GC4489@alberich.amd.com> Signed-off-by: H. Peter Anvin Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/process.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -459,11 +459,13 @@ static int __cpuinit check_c1e_idle(cons * check OSVW bit for CPUs that are not affected * by erratum #400 */ - rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, val); - if (val >= 2) { - rdmsrl(MSR_AMD64_OSVW_STATUS, val); - if (!(val & BIT(1))) - goto no_c1e_idle; + if (cpu_has(c, X86_FEATURE_OSVW)) { + rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, val); + if (val >= 2) { + rdmsrl(MSR_AMD64_OSVW_STATUS, val); + if (!(val & BIT(1))) + goto no_c1e_idle; + } } return 1; }