From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754175Ab1AGPhe (ORCPT ); Fri, 7 Jan 2011 10:37:34 -0500 Received: from hera.kernel.org ([140.211.167.34]:40875 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753900Ab1AGPhc (ORCPT ); Fri, 7 Jan 2011 10:37:32 -0500 Date: Fri, 7 Jan 2011 15:34:59 GMT From: tip-bot for Don Zickus Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, ying.huang@intel.com, tglx@linutronix.de, dzickus@redhat.com, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, ying.huang@intel.com, tglx@linutronix.de, dzickus@redhat.com, mingo@elte.hu In-Reply-To: <1294348732-15030-6-git-send-email-dzickus@redhat.com> References: <1294348732-15030-6-git-send-email-dzickus@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] x86, NMI: Allow NMI reason io port (0x61) to be processed on any CPU Message-ID: Git-Commit-ID: ab846f13f69fa64f8ed69ce0c3e239e075910d23 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Fri, 07 Jan 2011 15:34:59 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ab846f13f69fa64f8ed69ce0c3e239e075910d23 Gitweb: http://git.kernel.org/tip/ab846f13f69fa64f8ed69ce0c3e239e075910d23 Author: Don Zickus AuthorDate: Thu, 6 Jan 2011 16:18:51 -0500 Committer: Ingo Molnar CommitDate: Fri, 7 Jan 2011 15:08:53 +0100 x86, NMI: Allow NMI reason io port (0x61) to be processed on any CPU 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 Signed-off-by: Peter Zijlstra LKML-Reference: <1294348732-15030-6-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar --- 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