From mboxrd@z Thu Jan 1 00:00:00 1970 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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 8976FC4321A for ; Fri, 28 Jun 2019 11:22:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67D7E208C4 for ; Fri, 28 Jun 2019 11:22:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726873AbfF1LWC (ORCPT ); Fri, 28 Jun 2019 07:22:02 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:35300 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726730AbfF1LVu (ORCPT ); Fri, 28 Jun 2019 07:21:50 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hgowt-00022F-MM; Fri, 28 Jun 2019 13:21:47 +0200 Message-Id: <20190628111440.459647741@linutronix.de> User-Agent: quilt/0.65 Date: Fri, 28 Jun 2019 13:11:53 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Marc Zyngier , Robert Hodaszi Subject: [patch V2 5/6] x86/irq: Handle spurious interrupt after shutdown gracefully References: <20190628111148.828731433@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since the rework of the vector management, warnings about spurious interrupts have been reported. Robert provided some more information and did an initial analysis. The following situation leads to these warnings: CPU 0 CPU 1 IO_APIC interrupt is raised sent to CPU1 Unable to handle immediately (interrupts off, deep idle delay) mask() ... free() shutdown() synchronize_irq() clear_vector() do_IRQ() -> vector is clear Before the rework the vector entries of legacy interrupts were statically assigned and occupied precious vector space while most of them were unused. Due to that the above situation was handled silently because the vector was handled and the core handler of the assigned interrupt descriptor noticed that it is shut down and returned. While this has been usually observed with legacy interrupts, this situation is not limited to them. Any other interrupt source, e.g. MSI, can cause the same issue. After adding proper synchronization for level triggered interrupts, this can only happen for edge triggered interrupts where the IO-APIC obviously cannot provide information about interrupts in flight. While the spurious warning is actually harmless in this case it worries users and driver developers. Handle it gracefully by marking the vector entry as VECTOR_SHUTDOWN instead of VECTOR_UNUSED when the vector is freed up. If that above late handling happens the spurious detector will not complain and switch the entry to VECTOR_UNUSED. Any subsequent spurious interrupt on that line will trigger the spurious warning as before. Fixes: 464d12309e1b ("x86/vector: Switch IOAPIC to global reservation mode") Reported-by: Robert Hodaszi Signed-off-by: Thomas Gleixner - Tested-by: Robert Hodaszi --- V2: Picked up Tested-by from Robert. --- arch/x86/include/asm/hw_irq.h | 3 ++- arch/x86/kernel/apic/vector.c | 4 ++-- arch/x86/kernel/irq.c | 2 +- 3 files changed, 5 insertions(+), 4 deletions(-) --- a/arch/x86/include/asm/hw_irq.h +++ b/arch/x86/include/asm/hw_irq.h @@ -151,7 +151,8 @@ extern char irq_entries_start[]; #endif #define VECTOR_UNUSED NULL -#define VECTOR_RETRIGGERED ((void *)~0UL) +#define VECTOR_SHUTDOWN ((void *)~0UL) +#define VECTOR_RETRIGGERED ((void *)~1UL) typedef struct irq_desc* vector_irq_t[NR_VECTORS]; DECLARE_PER_CPU(vector_irq_t, vector_irq); --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -340,7 +340,7 @@ static void clear_irq_vector(struct irq_ trace_vector_clear(irqd->irq, vector, apicd->cpu, apicd->prev_vector, apicd->prev_cpu); - per_cpu(vector_irq, apicd->cpu)[vector] = VECTOR_UNUSED; + per_cpu(vector_irq, apicd->cpu)[vector] = VECTOR_SHUTDOWN; irq_matrix_free(vector_matrix, apicd->cpu, vector, managed); apicd->vector = 0; @@ -349,7 +349,7 @@ static void clear_irq_vector(struct irq_ if (!vector) return; - per_cpu(vector_irq, apicd->prev_cpu)[vector] = VECTOR_UNUSED; + per_cpu(vector_irq, apicd->prev_cpu)[vector] = VECTOR_SHUTDOWN; irq_matrix_free(vector_matrix, apicd->prev_cpu, vector, managed); apicd->prev_vector = 0; apicd->move_in_progress = 0; --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -247,7 +247,7 @@ u64 arch_irq_stat(void) if (!handle_irq(desc, regs)) { ack_APIC_irq(); - if (desc != VECTOR_RETRIGGERED) { + if (desc != VECTOR_RETRIGGERED && desc != VECTOR_SHUTDOWN) { pr_emerg_ratelimited("%s: %d.%d No irq handler for vector\n", __func__, smp_processor_id(), vector);