Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753692AbcDVLG3 (ORCPT ); Fri, 22 Apr 2016 07:06:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:43955 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753593AbcDVLG0 (ORCPT ); Fri, 22 Apr 2016 07:06:26 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Boris Ostrovsky , David Vrabel , Jiri Slaby Subject: [PATCH 3.12 47/78] xen/events: Mask a moving irq Date: Fri, 22 Apr 2016 13:05:30 +0200 Message-Id: X-Mailer: git-send-email 2.8.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2656 Lines: 95 From: Boris Ostrovsky 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit ff1e22e7a638a0782f54f81a6c9cb139aca2da35 upstream. Moving an unmasked irq may result in irq handler being invoked on both source and target CPUs. With 2-level this can happen as follows: On source CPU: evtchn_2l_handle_events() -> generic_handle_irq() -> handle_edge_irq() -> eoi_pirq(): irq_move_irq(data); /***** WE ARE HERE *****/ if (VALID_EVTCHN(evtchn)) clear_evtchn(evtchn); If at this moment target processor is handling an unrelated event in evtchn_2l_handle_events()'s loop it may pick up our event since target's cpu_evtchn_mask claims that this event belongs to it *and* the event is unmasked and still pending. At the same time, source CPU will continue executing its own handle_edge_irq(). With FIFO interrupt the scenario is similar: irq_move_irq() may result in a EVTCHNOP_unmask hypercall which, in turn, may make the event pending on the target CPU. We can avoid this situation by moving and clearing the event while keeping event masked. Signed-off-by: Boris Ostrovsky Signed-off-by: David Vrabel Signed-off-by: Jiri Slaby --- drivers/xen/events.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/drivers/xen/events.c b/drivers/xen/events.c index bd12a6660fe3..3715a54117bb 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -573,9 +573,19 @@ static void eoi_pirq(struct irq_data *data) struct physdev_eoi eoi = { .irq = pirq_from_irq(data->irq) }; int rc = 0; - irq_move_irq(data); + if (!VALID_EVTCHN(evtchn)) + return; - if (VALID_EVTCHN(evtchn)) + if (unlikely(irqd_is_setaffinity_pending(data))) { + int masked = test_and_set_mask(evtchn); + + clear_evtchn(evtchn); + + irq_move_masked_irq(data); + + if (!masked) + unmask_evtchn(evtchn); + } else clear_evtchn(evtchn); if (pirq_needs_eoi(data->irq)) { @@ -1603,9 +1613,19 @@ static void ack_dynirq(struct irq_data *data) { int evtchn = evtchn_from_irq(data->irq); - irq_move_irq(data); + if (!VALID_EVTCHN(evtchn)) + return; - if (VALID_EVTCHN(evtchn)) + if (unlikely(irqd_is_setaffinity_pending(data))) { + int masked = test_and_set_mask(evtchn); + + clear_evtchn(evtchn); + + irq_move_masked_irq(data); + + if (!masked) + unmask_evtchn(evtchn); + } else clear_evtchn(evtchn); } -- 2.8.1