From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933160Ab0JIGuB (ORCPT ); Sat, 9 Oct 2010 02:50:01 -0400 Received: from mga11.intel.com ([192.55.52.93]:7021 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754861Ab0JIGt6 (ORCPT ); Sat, 9 Oct 2010 02:49:58 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.57,307,1283756400"; d="scan'208";a="614941825" From: Huang Ying To: Don Zickus , Ingo Molnar , "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, Andi Kleen , Robert Richter , Huang Ying Subject: [PATCH -v3 4/6] Make NMI reason io port (0x61) can be processed on any CPU Date: Sat, 9 Oct 2010 14:49:45 +0800 Message-Id: <1286606987-19879-4-git-send-email-ying.huang@intel.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1286606987-19879-1-git-send-email-ying.huang@intel.com> References: <1286606987-19879-1-git-send-email-ying.huang@intel.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 make the port can be processed on any CPU. Signed-off-by: Huang Ying --- arch/x86/kernel/traps.c | 45 +++++++++++++++++++++++++-------------------- 1 file changed, 25 insertions(+), 20 deletions(-) --- 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, 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 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;