From a545715d2dae8d071c5b06af947b07ffa846b288 Mon Sep 17 00:00:00 2001 From: Prarit Bhargava Date: Wed, 30 Nov 2016 08:19:39 -0500 Subject: [PATCH] ACPI / APEI: Fix NMI notification handling 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. Fixes: 2383844d4850 (GHES: Elliminate double-loop in the NMI handler) Signed-off-by: Prarit Bhargava Reviewed-by: Borislav Petkov Signed-off-by: Rafael J. Wysocki --- 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; -- 2.45.2