From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33441 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753148AbcDMUrh (ORCPT ); Wed, 13 Apr 2016 16:47:37 -0400 Subject: Patch "xen/events: Mask a moving irq" has been added to the 4.4-stable tree To: boris.ostrovsky@oracle.com, david.vrabel@citrix.com, gregkh@linuxfoundation.org Cc: , From: Date: Wed, 13 Apr 2016 13:47:36 -0700 Message-ID: <146058045621642@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled xen/events: Mask a moving irq to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xen-events-mask-a-moving-irq.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From ff1e22e7a638a0782f54f81a6c9cb139aca2da35 Mon Sep 17 00:00:00 2001 From: Boris Ostrovsky Date: Fri, 18 Mar 2016 10:11:07 -0400 Subject: xen/events: Mask a moving irq From: Boris Ostrovsky 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: Greg Kroah-Hartman --- drivers/xen/events/events_base.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -484,9 +484,19 @@ static void eoi_pirq(struct irq_data *da 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)) { @@ -1357,9 +1367,19 @@ static void ack_dynirq(struct irq_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); } Patches currently in stable-queue which might be from boris.ostrovsky@oracle.com are queue-4.4/xen-events-mask-a-moving-irq.patch