Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757071AbcK3NTz (ORCPT ); Wed, 30 Nov 2016 08:19:55 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41726 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752845AbcK3NTp (ORCPT ); Wed, 30 Nov 2016 08:19:45 -0500 From: Prarit Bhargava To: linux-kernel@vger.kernel.org Cc: Prarit Bhargava , Borislav Petkov , "Rafael J. Wysocki" , Len Brown , Paul Gortmaker , Tyler Baicar , Punit Agrawal , Don Zickus Subject: [PATCH v2] ACPI / APEI: Fix NMI notification handling Date: Wed, 30 Nov 2016 08:19:39 -0500 Message-Id: <1480511979-11722-1-git-send-email-prarit@redhat.com> In-Reply-To: <20161129193624.krjz2bpinl2ioi7o@pd.tnic> References: <20161129193624.krjz2bpinl2ioi7o@pd.tnic> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 30 Nov 2016 13:19:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2927 Lines: 81 When removing and adding cpu 0 on a system with GHES NMI the following stack trace is seen when re-adding the cpu: WARNING: CPU: 0 PID: 0 at arch/x86/kernel/apic/apic.c:1349 setup_local_APIC+ Modules linked in: nfsv3 rpcsec_gss_krb5 nfsv4 nfs fscache coretemp intel_ra CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.0-rc6+ #2 Call Trace: dump_stack+0x63/0x8e __warn+0xd1/0xf0 warn_slowpath_null+0x1d/0x20 setup_local_APIC+0x275/0x370 apic_ap_setup+0xe/0x20 start_secondary+0x48/0x180 set_init_arg+0x55/0x55 early_idt_handler_array+0x120/0x120 x86_64_start_reservations+0x2a/0x2c x86_64_start_kernel+0x13d/0x14c During the cpu bringup, wakeup_cpu_via_init_nmi() is called and issues an NMI on CPU 0. The GHES NMI handler, ghes_notify_nmi() runs the ghes_proc_irq_work work queue which ends up setting IRQ_WORK_VECTOR (0xf6). The "faulty" IR line set at arch/x86/kernel/apic/apic.c:1349 is also 0xf6 (specifically APIC IRR for irqs 255 to 224 is 0x400000) which confirms that something has set the IRQ_WORK_VECTOR line prior to the APIC being initialized. Commit 2383844d4850 ("GHES: Elliminate double-loop in the NMI handler") incorrectly modified the behavior such that the handler returns NMI_HANDLED only if an error was processed, and incorrectly runs the ghes work queue for every NMI. This patch modifies the ghes_proc_irq_work() to run as it did prior to 2383844d4850 ("GHES: Elliminate double-loop in the NMI handler") by properly returning NMI_HANDLED and only calling the work queue if NMI_HANDLED has been set. v2: Borislav, setting of NMI_HANDLED moved & cleaned up changelog. Fixes: 2383844d4850 ("GHES: Elliminate double-loop in the NMI handler") Signed-off-by: Prarit Bhargava Cc: Borislav Petkov Cc: Rafael J. Wysocki Cc: Len Brown Cc: Paul Gortmaker Cc: Tyler Baicar Cc: Punit Agrawal Cc: Don Zickus --- drivers/acpi/apei/ghes.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 0d099a24f776..e53bef6cf53c 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -852,6 +852,8 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs) if (ghes_read_estatus(ghes, 1)) { ghes_clear_estatus(ghes); continue; + } else { + ret = NMI_HANDLED; } sev = ghes_severity(ghes->estatus->error_severity); @@ -863,12 +865,11 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs) __process_error(ghes); ghes_clear_estatus(ghes); - - ret = NMI_HANDLED; } #ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG - irq_work_queue(&ghes_proc_irq_work); + if (ret == NMI_HANDLED) + irq_work_queue(&ghes_proc_irq_work); #endif atomic_dec(&ghes_in_nmi); return ret; -- 1.7.9.3