Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754160AbbLJBtc (ORCPT ); Wed, 9 Dec 2015 20:49:32 -0500 Received: from mail9.hitachi.co.jp ([133.145.228.44]:41541 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591AbbLJBtV (ORCPT ); Wed, 9 Dec 2015 20:49:21 -0500 X-AuditID: 85900ec0-9d7c9b9000001a57-d4-5668da1dd77d X-Mailbox-Line: From nobody Thu Dec 10 10:46:34 2015 Subject: [V6 PATCH 4/6] x86/apic: Introduce apic_extnmi boot option To: Jonathan Corbet , Peter Zijlstra , Ingo Molnar , "Eric W. Biederman" , "H. Peter Anvin" , Andrew Morton , Thomas Gleixner , Vivek Goyal From: Hidehiro Kawai Cc: Baoquan He , linux-doc@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Steven Rostedt , Michal Hocko , Ingo Molnar , Borislav Petkov , Masami Hiramatsu Date: Thu, 10 Dec 2015 10:46:32 +0900 Message-ID: <20151210014632.25437.43778.stgit@softrs> In-Reply-To: <20151210014624.25437.50028.stgit@softrs> References: <20151210014624.25437.50028.stgit@softrs> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4830 Lines: 142 This patch introduces new boot option, apic_extnmi: apic_extnmi={ bsp | all | none} The default value is "bsp" and this is the current behavior; only BSP receives external NMI. "all" allows external NMIs to be broadcast to all CPUs. This would raise the success rate of panic on NMI when BSP hangs up in NMI context or the external NMI is swallowed by other NMI handlers on BSP. If you specified "none", any CPUs don't receive external NMIs. This is useful for dump capture kernel so that it wouldn't be shot down while saving a crash dump. V6: - Fix comments - Change to use strncmp to parse the value of "apic_extnmi=" - Make apic_set_extnmi() return -EINVAL if the given value is invalid V5: - Rename the option from "noextnmi" to "apic_extnmi" - Add apic_extnmi=all feature - Fix the wrong documentation about "noextnmi" (apic_extnmi=none) Signed-off-by: Hidehiro Kawai Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Jonathan Corbet --- Documentation/kernel-parameters.txt | 9 +++++++++ arch/x86/include/asm/apic.h | 5 +++++ arch/x86/kernel/apic/apic.c | 35 +++++++++++++++++++++++++++++++++-- 3 files changed, 47 insertions(+), 2 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 742f69d..74acea5 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -472,6 +472,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Change the amount of debugging information output when initialising the APIC and IO-APIC components. + apic_extnmi= [APIC,X86] External NMI delivery setting + Format: { bsp (default) | all | none } + bsp: External NMI is delivered only to CPU 0 + all: External NMIs are broadcast to all CPUs as a + backup of CPU 0 + none: External NMI is masked for all CPUs. This is + useful so that a dump capture kernel won't be + shot down by NMI + autoconf= [IPV6] See Documentation/networking/ipv6.txt. diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 7f62ad4..c80f6b6 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -23,6 +23,11 @@ #define APIC_VERBOSE 1 #define APIC_DEBUG 2 +/* Macros for apic_extnmi which controls external NMI masking */ +#define APIC_EXTNMI_BSP 0 /* Default */ +#define APIC_EXTNMI_ALL 1 +#define APIC_EXTNMI_NONE 2 + /* * Define the default level of output to be very little * This can be turned up by using apic=verbose for more diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 8d7df74..162d2bd 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -82,6 +82,12 @@ physid_mask_t phys_cpu_present_map; static unsigned int disabled_cpu_apicid __read_mostly = BAD_APICID; /* + * This variable controls which CPUs receive external NMIs. By default, + * external NMIs are delivered only to the BSP. + */ +static int apic_extnmi = APIC_EXTNMI_BSP; + +/* * Map cpu index to physical APIC ID */ DEFINE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid, BAD_APICID); @@ -1161,6 +1167,8 @@ void __init init_bsp_APIC(void) value = APIC_DM_NMI; if (!lapic_is_integrated()) /* 82489DX */ value |= APIC_LVT_LEVEL_TRIGGER; + if (apic_extnmi == APIC_EXTNMI_NONE) + value |= APIC_LVT_MASKED; apic_write(APIC_LVT1, value); } @@ -1378,9 +1386,11 @@ void setup_local_APIC(void) apic_write(APIC_LVT0, value); /* - * only the BP should see the LINT1 NMI signal, obviously. + * Only the BP sees the LINT1 NMI signal by default. This can be + * modified by apic_extnmi= boot option. */ - if (!cpu) + if ((!cpu && apic_extnmi != APIC_EXTNMI_NONE) || + apic_extnmi == APIC_EXTNMI_ALL) value = APIC_DM_NMI; else value = APIC_DM_NMI | APIC_LVT_MASKED; @@ -2557,3 +2567,24 @@ static int __init apic_set_disabled_cpu_apicid(char *arg) return 0; } early_param("disable_cpu_apicid", apic_set_disabled_cpu_apicid); + +static int __init apic_set_extnmi(char *arg) +{ + if (!arg) + return -EINVAL; + + if (!strncmp("all", arg, 3)) + apic_extnmi = APIC_EXTNMI_ALL; + else if (!strncmp("none", arg, 4)) + apic_extnmi = APIC_EXTNMI_NONE; + else if (!strncmp("bsp", arg, 3)) + apic_extnmi = APIC_EXTNMI_BSP; + else { + pr_warn("Unknown external NMI delivery mode `%s' ignored\n", + arg); + return -EINVAL; + } + + return 0; +} +early_param("apic_extnmi", apic_set_extnmi); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/