From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: [PATCH 1/3] x86/xen: use memory barriers when enabling local irqs Date: Tue, 13 Aug 2013 15:31:34 +0100 Message-ID: <1376404296-7012-2-git-send-email-david.vrabel@citrix.com> References: <1376404296-7012-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1376404296-7012-1-git-send-email-david.vrabel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org Cc: Boris Ostrovsky , David Vrabel List-Id: xen-devel@lists.xenproject.org From: David Vrabel Because vcpu->evtchn_upcall_mask and vcpu->evtchn_upcall_pending are be written by Xen as well as the guest, using barrier() (a compiler-only barrier) in xen_enable_irq() and xen_restore_fl() is not sufficient. Use mb() (a full memory barrier) instead. Signed-off-by: David Vrabel --- arch/x86/xen/irq.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c index 01a4dc0..1a8d0d4 100644 --- a/arch/x86/xen/irq.c +++ b/arch/x86/xen/irq.c @@ -60,7 +60,7 @@ static void xen_restore_fl(unsigned long flags) if (flags == 0) { preempt_check_resched(); - barrier(); /* unmask then check (avoid races) */ + mb(); /* unmask then check (avoid races) */ if (unlikely(vcpu->evtchn_upcall_pending)) xen_force_evtchn_callback(); } @@ -93,7 +93,7 @@ static void xen_irq_enable(void) /* Doesn't matter if we get preempted here, because any pending event will get dealt with anyway. */ - barrier(); /* unmask then check (avoid races) */ + mb(); /* unmask then check (avoid races) */ if (unlikely(vcpu->evtchn_upcall_pending)) xen_force_evtchn_callback(); } -- 1.7.2.5