Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755663AbZJFAu5 (ORCPT ); Mon, 5 Oct 2009 20:50:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755607AbZJFAuz (ORCPT ); Mon, 5 Oct 2009 20:50:55 -0400 Received: from claw.goop.org ([74.207.240.146]:35235 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753600AbZJFAux (ORCPT ); Mon, 5 Oct 2009 20:50:53 -0400 From: Jeremy Fitzhardinge To: Xen-devel Cc: Linux Kernel Mailing List , kurt.hackel@oracle.com, Dan Magenheimer , Keir Fraser , Glauber de Oliveira Costa , Avi Kivity , Zach Brown , the arch/x86 maintainers , Chris Mason , Jeremy Fitzhardinge Subject: [PATCH 1/5] x86/pvclock: make sure rdtsc doesn't speculate out of region Date: Mon, 5 Oct 2009 17:50:07 -0700 Message-Id: <1254790211-15416-2-git-send-email-jeremy.fitzhardinge@citrix.com> X-Mailer: git-send-email 1.6.2.5 In-Reply-To: <1254790211-15416-1-git-send-email-jeremy.fitzhardinge@citrix.com> References: <1254790211-15416-1-git-send-email-jeremy.fitzhardinge@citrix.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1111 Lines: 34 rdtsc is not necessarily ordered with surrounding instructions so we need to make sure that it doesn't get sampled out of order with respect to reading the time_info. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/kernel/pvclock.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 03801f2..963f349 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -117,10 +117,10 @@ cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) do { version = pvclock_get_time_values(&shadow, src); - barrier(); + rdtsc_barrier(); offset = pvclock_get_nsec_offset(&shadow); ret = shadow.system_timestamp + offset; - barrier(); + rdtsc_barrier(); } while (version != src->version); return ret; -- 1.6.2.5 -- 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/