From patchwork Mon Mar 15 13:58:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 401228 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6964BC43331 for ; Mon, 15 Mar 2021 14:08:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 403E1600EF for ; Mon, 15 Mar 2021 14:08:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235004AbhCOOGz (ORCPT ); Mon, 15 Mar 2021 10:06:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:36622 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233298AbhCOOBW (ORCPT ); Mon, 15 Mar 2021 10:01:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 053EE64E89; Mon, 15 Mar 2021 14:00:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615816840; bh=HxQmE0RP0LzC8UMxFs5pgAUqlRaAFNSF8+QAirZSGeo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0rVM9leCwbZdtNlChMTwNe+OBXWWWMTLTbNiPNRnyyyEO0XS+s8aLhULhBqVdIPEm 8Pd923PijMDh/wtS9alVOJEOceP9ckZNHIHCN80NVE6C0o+XaoqY4iruRyNQexkPdM 8DElCtdyhk5Pm1ecapNw3ITUY7RQAcnhK9X1z56c= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Julien Grall , Juergen Gross , Julien Grall , Boris Ostrovsky Subject: [PATCH 4.14 95/95] xen/events: avoid handling the same event on two cpus at the same time Date: Mon, 15 Mar 2021 14:58:05 +0100 Message-Id: <20210315135743.403598567@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135740.245494252@linuxfoundation.org> References: <20210315135740.245494252@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Greg Kroah-Hartman From: Juergen Gross commit b6622798bc50b625a1e62f82c7190df40c1f5b21 upstream. When changing the cpu affinity of an event it can happen today that (with some unlucky timing) the same event will be handled on the old and the new cpu at the same time. Avoid that by adding an "event active" flag to the per-event data and call the handler only if this flag isn't set. Cc: stable@vger.kernel.org Reported-by: Julien Grall Signed-off-by: Juergen Gross Reviewed-by: Julien Grall Link: https://lore.kernel.org/r/20210306161833.4552-4-jgross@suse.com Signed-off-by: Boris Ostrovsky Signed-off-by: Greg Kroah-Hartman --- drivers/xen/events/events_base.c | 25 +++++++++++++++++-------- drivers/xen/events/events_internal.h | 1 + 2 files changed, 18 insertions(+), 8 deletions(-) --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -693,6 +693,12 @@ static void xen_evtchn_close(unsigned in BUG(); } +static void event_handler_exit(struct irq_info *info) +{ + smp_store_release(&info->is_active, 0); + clear_evtchn(info->evtchn); +} + static void pirq_query_unmask(int irq) { struct physdev_irq_status_query irq_status; @@ -723,13 +729,13 @@ static void eoi_pirq(struct irq_data *da likely(!irqd_irq_disabled(data))) { do_mask(info, EVT_MASK_REASON_TEMPORARY); - clear_evtchn(evtchn); + event_handler_exit(info); irq_move_masked_irq(data); do_unmask(info, EVT_MASK_REASON_TEMPORARY); } else - clear_evtchn(evtchn); + event_handler_exit(info); if (pirq_needs_eoi(data->irq)) { rc = HYPERVISOR_physdev_op(PHYSDEVOP_eoi, &eoi); @@ -1565,6 +1571,8 @@ void handle_irq_for_port(evtchn_port_t p } info = info_for_irq(irq); + if (xchg_acquire(&info->is_active, 1)) + return; if (ctrl->defer_eoi) { info->eoi_cpu = smp_processor_id(); @@ -1752,13 +1760,13 @@ static void ack_dynirq(struct irq_data * likely(!irqd_irq_disabled(data))) { do_mask(info, EVT_MASK_REASON_TEMPORARY); - clear_evtchn(evtchn); + event_handler_exit(info); irq_move_masked_irq(data); do_unmask(info, EVT_MASK_REASON_TEMPORARY); } else - clear_evtchn(evtchn); + event_handler_exit(info); } static void mask_ack_dynirq(struct irq_data *data) @@ -1774,7 +1782,7 @@ static void lateeoi_ack_dynirq(struct ir if (VALID_EVTCHN(evtchn)) { do_mask(info, EVT_MASK_REASON_EOI_PENDING); - clear_evtchn(evtchn); + event_handler_exit(info); } } @@ -1785,7 +1793,7 @@ static void lateeoi_mask_ack_dynirq(stru if (VALID_EVTCHN(evtchn)) { do_mask(info, EVT_MASK_REASON_EXPLICIT); - clear_evtchn(evtchn); + event_handler_exit(info); } } @@ -1894,10 +1902,11 @@ static void restore_cpu_ipis(unsigned in /* Clear an irq's pending state, in preparation for polling on it */ void xen_clear_irq_pending(int irq) { - int evtchn = evtchn_from_irq(irq); + struct irq_info *info = info_for_irq(irq); + evtchn_port_t evtchn = info ? info->evtchn : 0; if (VALID_EVTCHN(evtchn)) - clear_evtchn(evtchn); + event_handler_exit(info); } EXPORT_SYMBOL(xen_clear_irq_pending); void xen_set_irq_pending(int irq) --- a/drivers/xen/events/events_internal.h +++ b/drivers/xen/events/events_internal.h @@ -40,6 +40,7 @@ struct irq_info { #define EVT_MASK_REASON_EXPLICIT 0x01 #define EVT_MASK_REASON_TEMPORARY 0x02 #define EVT_MASK_REASON_EOI_PENDING 0x04 + u8 is_active; /* Is event just being handled? */ unsigned irq; unsigned int evtchn; /* event channel */ unsigned short cpu; /* cpu bound */