From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752735Ab0JPCXn (ORCPT ); Fri, 15 Oct 2010 22:23:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43007 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752483Ab0JPCW7 (ORCPT ); Fri, 15 Oct 2010 22:22:59 -0400 From: Don Zickus To: mingo@elte.hu Cc: andi@firstfloor.org, robert.richter@amd.com, linux-kernel@vger.kernel.org, peterz@infradead.org, ying.huang@intel.com, Don Zickus Subject: [PATCH 4/5] x86, NMI: Allow NMI reason io port (0x61) to be processed on any CPU Date: Fri, 15 Oct 2010 22:22:17 -0400 Message-Id: <1287195738-3136-5-git-send-email-dzickus@redhat.com> In-Reply-To: <1287195738-3136-1-git-send-email-dzickus@redhat.com> References: <1287195738-3136-1-git-send-email-dzickus@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Huang Ying 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 make the port can be processed on any CPU. Signed-off-by: Huang Ying Signed-off-by: Don Zickus --- arch/x86/kernel/traps.c | 45 +++++++++++++++++++++++++-------------------- 1 files changed, 25 insertions(+), 20 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index d8acab3..accb2f4 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -83,6 +83,12 @@ EXPORT_SYMBOL_GPL(used_vectors); static int ignore_nmis; +/* + * 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) { if (regs->flags & X86_EFLAGS_IF) @@ -383,7 +389,6 @@ 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 @@ -400,28 +405,28 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs) return; /* Non-CPU-specific NMI: NMI sources can be processed on any CPU */ - cpu = smp_processor_id(); - /* Only the BSP gets external NMIs from the system. */ - if (!cpu) { - reason = get_nmi_reason(); - if (reason & NMI_REASON_MASK) { - if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) - == NOTIFY_STOP) - return; - if (reason & NMI_REASON_SERR) - pci_serr_error(reason, regs); - else if (reason & NMI_REASON_IOCHK) - io_check_error(reason, regs); + raw_spin_lock(&nmi_reason_lock); + reason = get_nmi_reason(); + if (reason & NMI_REASON_MASK) { + if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) + == NOTIFY_STOP) + goto unlock_return; + if (reason & NMI_REASON_SERR) + pci_serr_error(reason, regs); + else if (reason & NMI_REASON_IOCHK) + io_check_error(reason, regs); #ifdef CONFIG_X86_32 - /* - * Reassert NMI in case it became active - * meanwhile as it's edge-triggered: - */ - reassert_nmi(); + /* + * Reassert NMI in case it became active + * meanwhile as it's edge-triggered: + */ + reassert_nmi(); #endif - return; - } +unlock_return: + raw_spin_unlock(&nmi_reason_lock); + return; } + raw_spin_unlock(&nmi_reason_lock); if (notify_die(DIE_NMI, "nmi", regs, 0, 2, SIGINT) == NOTIFY_STOP) return; -- 1.7.2.3