From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759994Ab3CHXvU (ORCPT ); Fri, 8 Mar 2013 18:51:20 -0500 Received: from mga02.intel.com ([134.134.136.20]:50380 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754610Ab3CHXvT (ORCPT ); Fri, 8 Mar 2013 18:51:19 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,810,1355126400"; d="scan'208";a="274510211" From: Andi Kleen To: a.p.zijlstra@chello.nl Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, Andi Kleen Subject: [PATCH 4/5] perf, x86: Move NMI clearing to end of PMI handler after the counter registers are reset Date: Fri, 8 Mar 2013 15:49:32 -0800 Message-Id: <1362786573-18455-5-git-send-email-andi@firstfloor.org> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <1362786573-18455-1-git-send-email-andi@firstfloor.org> References: <1362786573-18455-1-git-send-email-andi@firstfloor.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andi Kleen This avoids some problems with spurious PMIs on Haswell. Haswell seems to behave more like P4 in this regard. Do the same thing as the P4 perf handler by unmasking the NMI only at the end. Shouldn't make any difference for earlier family 6 cores. Tested on Haswell, IvyBridge, Westmere, Saltwell (Atom) Signed-off-by: Andi Kleen --- arch/x86/kernel/cpu/perf_event_intel.c | 16 ++++++---------- 1 files changed, 6 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index ca3b611..6f22479 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1149,16 +1149,6 @@ static int intel_pmu_handle_irq(struct pt_regs *regs) cpuc = &__get_cpu_var(cpu_hw_events); - /* - * Some chipsets need to unmask the LVTPC in a particular spot - * inside the nmi handler. As a result, the unmasking was pushed - * into all the nmi handlers. - * - * This handler doesn't seem to have any issues with the unmasking - * so it was left at the top. - */ - apic_write(APIC_LVTPC, APIC_DM_NMI); - intel_pmu_disable_all(); handled = intel_pmu_drain_bts_buffer(); status = intel_pmu_get_status(); @@ -1218,6 +1208,12 @@ again: done: intel_pmu_enable_all(0); + /* + * Only unmask the NMI after the overflow counters + * have been reset. This avoids spurious NMIs on + * Haswell CPUs. + */ + apic_write(APIC_LVTPC, APIC_DM_NMI); return handled; } -- 1.7.7.6