From patchwork Wed Apr 24 19:33:02 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fenghua Yu X-Patchwork-Id: 10915589 X-Patchwork-Delegate: johannes@sipsolutions.net Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6487C922 for ; Wed, 24 Apr 2019 19:42:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 53AEE28C47 for ; Wed, 24 Apr 2019 19:42:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 476C828C4D; Wed, 24 Apr 2019 19:42:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A53F728B94 for ; Wed, 24 Apr 2019 19:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389734AbfDXTlp (ORCPT ); Wed, 24 Apr 2019 15:41:45 -0400 Received: from mga18.intel.com ([134.134.136.126]:44995 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729820AbfDXTln (ORCPT ); Wed, 24 Apr 2019 15:41:43 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Apr 2019 12:41:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,390,1549958400"; d="scan'208";a="340454911" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by fmsmga005.fm.intel.com with ESMTP; 24 Apr 2019 12:41:41 -0700 From: Fenghua Yu To: "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "H Peter Anvin" , "Paolo Bonzini" , "Dave Hansen" , "Ashok Raj" , "Peter Zijlstra" , "Ravi V Shankar" , "Xiaoyao Li " , "Christopherson Sean J" , "Kalle Valo" , "Michael Chan" Cc: "linux-kernel" , "x86" , kvm@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, Fenghua Yu Subject: [PATCH v8 15/15] x86/split_lock: Add a sysfs interface to enable/disable split lock detection during run time Date: Wed, 24 Apr 2019 12:33:02 -0700 Message-Id: <1556134382-58814-16-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1556134382-58814-1-git-send-email-fenghua.yu@intel.com> References: <1556134382-58814-1-git-send-email-fenghua.yu@intel.com> Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP To workaround or debug a split lock issue, the administrator may need to disable or enable split lock detection during run time without rebooting the system. The interface /sys/device/system/cpu/split_lock_detect is added to allow the administrator to disable or enable split lock detection and show current split lock detection setting. Writing [yY1] or [oO][nN] to the file enables split lock detection and writing [nN0] or [oO][fF] disables split lock detection. Split lock detection is enabled or disabled on all CPUs. Reading the file returns current global split lock detection setting: 0: disabled 1: enabled Add an ABI document entry for /sys/devices/system/cpu/split_lock_detect. Signed-off-by: Fenghua Yu --- Not sure if the justification for the sysfs knob is valid. If not, this patch could be removed from this patch set. .../ABI/testing/sysfs-devices-system-cpu | 22 ++++++++ arch/x86/kernel/cpu/intel.c | 52 ++++++++++++++++++- 2 files changed, 72 insertions(+), 2 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index 9605dbd4b5b5..aad7b1698065 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -67,6 +67,28 @@ Description: Discover NUMA node a CPU belongs to /sys/devices/system/cpu/cpu42/node2 -> ../../node/node2 +What: /sys/devices/system/cpu/split_lock_detect +Date: March 2019 +Contact: Linux kernel mailing list +Description: (RW) Control split lock detection on Intel Tremont and + future CPUs + + Reads return split lock detection status: + 0: disabled + 1: enabled + + Writes enable or disable split lock detection: + The first character is one of 'Nn0' or [oO][fF] for off + disables the feature. + The first character is one of 'Yy1' or [oO][nN] for on + enables the feature. + + Please note the interface only shows or controls global setting. + During run time, split lock detection on one CPU may be + disabled if split lock operation in kernel code happens on + the CPU. The interface doesn't show or control split lock + detection on individual CPU. + What: /sys/devices/system/cpu/cpu#/topology/core_id /sys/devices/system/cpu/cpu#/topology/core_siblings /sys/devices/system/cpu/cpu#/topology/core_siblings_list diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 959ebf25beda..f257d1e92706 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -35,6 +35,7 @@ DEFINE_PER_CPU(u64, msr_test_ctl_cache); EXPORT_PER_CPU_SYMBOL_GPL(msr_test_ctl_cache); +static DEFINE_MUTEX(split_lock_detect_mutex); static bool split_lock_detect_enable; /* @@ -660,7 +661,7 @@ static void init_intel_misc_features(struct cpuinfo_x86 *c) wrmsrl(MSR_MISC_FEATURES_ENABLES, msr); } -static void split_lock_update_msr(void) +static void split_lock_update_msr(void *__unused) { if (split_lock_detect_enable) { /* Enable split lock detection */ @@ -682,7 +683,7 @@ static void init_split_lock_detect(struct cpuinfo_x86 *c) rdmsrl(MSR_TEST_CTL, test_ctl_val); this_cpu_write(msr_test_ctl_cache, test_ctl_val); - split_lock_update_msr(); + split_lock_update_msr(NULL); } } @@ -1114,3 +1115,50 @@ void handle_split_lock_kernel_mode(void) this_cpu_and(msr_test_ctl_cache, ~TEST_CTL_SPLIT_LOCK_DETECT); WARN_ONCE(1, "split lock operation detected\n"); } + +static ssize_t +split_lock_detect_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + return sprintf(buf, "%u\n", split_lock_detect_enable); +} + +static ssize_t +split_lock_detect_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + bool val; + int ret; + + ret = strtobool(buf, &val); + if (ret) + return ret; + + mutex_lock(&split_lock_detect_mutex); + + split_lock_detect_enable = val; + + /* Update the split lock detection setting in MSR on all online CPUs. */ + on_each_cpu(split_lock_update_msr, NULL, 1); + + if (split_lock_detect_enable) + pr_info("enabled\n"); + else + pr_info("disabled\n"); + + mutex_unlock(&split_lock_detect_mutex); + + return count; +} + +static DEVICE_ATTR_RW(split_lock_detect); + +static int __init split_lock_init(void) +{ + if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) + return -ENODEV; + + return device_create_file(cpu_subsys.dev_root, + &dev_attr_split_lock_detect); +} +subsys_initcall(split_lock_init);