Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933489AbZJNTas (ORCPT ); Wed, 14 Oct 2009 15:30:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759110AbZJNT37 (ORCPT ); Wed, 14 Oct 2009 15:29:59 -0400 Received: from claw.goop.org ([74.207.240.146]:55336 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751674AbZJNT35 (ORCPT ); Wed, 14 Oct 2009 15:29:57 -0400 From: Jeremy Fitzhardinge To: Linux Kernel Mailing List Cc: Xen-devel , kurt.hackel@oracle.com, Glauber de Oliveira Costa , Avi Kivity , the arch/x86 maintainers , Chris Mason , Jeremy Fitzhardinge , Ingo Molnar , Gerd Hoffmann Subject: [PATCH 06/12] x86/pvclock: make sure rdtsc doesn't speculate out of region Date: Wed, 14 Oct 2009 12:28:30 -0700 Message-Id: <1255548516-15260-7-git-send-email-jeremy.fitzhardinge@citrix.com> X-Mailer: git-send-email 1.6.2.5 In-Reply-To: <1255548516-15260-1-git-send-email-jeremy.fitzhardinge@citrix.com> References: <1255548516-15260-1-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: 1251 Lines: 38 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 Cc: Avi Kivity Cc: Ingo Molnar Cc: Glauber Costa Cc: Gerd Hoffmann --- 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/