From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754027Ab1AFVTl (ORCPT ); Thu, 6 Jan 2011 16:19:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:28395 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754004Ab1AFVTj (ORCPT ); Thu, 6 Jan 2011 16:19:39 -0500 From: Don Zickus To: x86@kernel.org Cc: Peter Zijlstra , Robert Richter , ying.huang@intel.com, gorcunov@gmail.com, LKML , Don Zickus Subject: [PATCH 5/6] x86, NMI: Allow NMI reason io port (0x61) to be processed on any CPU Date: Thu, 6 Jan 2011 16:18:51 -0500 Message-Id: <1294348732-15030-6-git-send-email-dzickus@redhat.com> In-Reply-To: <1294348732-15030-1-git-send-email-dzickus@redhat.com> References: <1294348732-15030-1-git-send-email-dzickus@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In original NMI handler, NMI reason io port (0x61) is only processed on BSP. This makes it impossible to hot-remove BSP. To solve the issue, a raw spinlock is used to allow the port to be processed on any CPU. Originally-by: Huang Ying Signed-off-by: Don Zickus --- arch/x86/kernel/traps.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 23f6ac0..613b3d2 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -84,6 +84,11 @@ EXPORT_SYMBOL_GPL(used_vectors); static int ignore_nmis; int unknown_nmi_panic; +/* + * Prevent NMI reason port (0x61) being accessed simultaneously, can + * only be used in NMI handler. + */ +static DEFINE_RAW_SPINLOCK(nmi_reason_lock); static inline void conditional_sti(struct pt_regs *regs) { @@ -392,7 +397,6 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs) static notrace __kprobes void default_do_nmi(struct pt_regs *regs) { unsigned char reason = 0; - int cpu; /* * CPU-specific NMI must be processed before non-CPU-specific @@ -402,13 +406,12 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs) if (notify_die(DIE_NMI, "nmi", regs, 0, 2, SIGINT) == NOTIFY_STOP) return; - cpu = smp_processor_id(); - - /* Only the BSP gets external NMIs from the system. */ - if (!cpu) - reason = get_nmi_reason(); + /* Non-CPU-specific NMI: NMI sources can be processed on any CPU */ + raw_spin_lock(&nmi_reason_lock); + reason = get_nmi_reason(); if (!(reason & NMI_REASON_MASK)) { + raw_spin_unlock(&nmi_reason_lock); unknown_nmi_error(reason, regs); return; @@ -426,6 +429,7 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs) */ reassert_nmi(); #endif + raw_spin_unlock(&nmi_reason_lock); } dotraplinkage notrace __kprobes void -- 1.7.3.4