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Message-ID: <tip-6089327f5424f227bb6a8cf92363c2617e054453@git.kernel.org>
Date: Tue, 23 May 2017 01:40:49 -0700
From: tip-bot for Kan Liang <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: jolsa@...hat.com, tglx@...utronix.de, peterz@...radead.org,
alexander.shishkin@...ux.intel.com, torvalds@...ux-foundation.org,
linux-kernel@...r.kernel.org, acme@...hat.com, eranian@...gle.com,
Kan.liang@...el.com, vincent.weaver@...ne.edu, mingo@...nel.org,
hpa@...or.com
Subject: [tip:perf/core] perf/x86: Add sysfs entry to freeze counters on SMI
Commit-ID: 6089327f5424f227bb6a8cf92363c2617e054453
Gitweb: http://git.kernel.org/tip/6089327f5424f227bb6a8cf92363c2617e054453
Author: Kan Liang <Kan.liang@...el.com>
AuthorDate: Fri, 12 May 2017 07:51:13 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 23 May 2017 09:50:04 +0200
perf/x86: Add sysfs entry to freeze counters on SMI
Currently, the SMIs are visible to all performance counters, because
many users want to measure everything including SMIs. But in some
cases, the SMI cycles should not be counted - for example, to calculate
the cost of an SMI itself. So a knob is needed.
When setting FREEZE_WHILE_SMM bit in IA32_DEBUGCTL, all performance
counters will be effected. There is no way to do per-counter freeze
on SMI. So it should not use the per-event interface (e.g. ioctl or
event attribute) to set FREEZE_WHILE_SMM bit.
Adds sysfs entry /sys/device/cpu/freeze_on_smi to set FREEZE_WHILE_SMM
bit in IA32_DEBUGCTL. When set, freezes perfmon and trace messages
while in SMM.
Value has to be 0 or 1. It will be applied to all processors.
Also serialize the entire setting so we don't get multiple concurrent
threads trying to update to different values.
Signed-off-by: Kan Liang <Kan.liang@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Cc: acme@...nel.org
Cc: bp@...en8.de
Cc: jolsa@...nel.org
Link: http://lkml.kernel.org/r/1494600673-244667-1-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/events/core.c | 10 +++++++
arch/x86/events/intel/core.c | 63 ++++++++++++++++++++++++++++++++++++++++
arch/x86/events/perf_event.h | 3 ++
arch/x86/include/asm/msr-index.h | 2 ++
4 files changed, 78 insertions(+)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 580b60f..e6f5e4b 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1750,6 +1750,8 @@ ssize_t x86_event_sysfs_show(char *page, u64 config, u64 event)
return ret;
}
+static struct attribute_group x86_pmu_attr_group;
+
static int __init init_hw_perf_events(void)
{
struct x86_pmu_quirk *quirk;
@@ -1813,6 +1815,14 @@ static int __init init_hw_perf_events(void)
x86_pmu_events_group.attrs = tmp;
}
+ if (x86_pmu.attrs) {
+ struct attribute **tmp;
+
+ tmp = merge_attr(x86_pmu_attr_group.attrs, x86_pmu.attrs);
+ if (!WARN_ON(!tmp))
+ x86_pmu_attr_group.attrs = tmp;
+ }
+
pr_info("... version: %d\n", x86_pmu.version);
pr_info("... bit width: %d\n", x86_pmu.cntval_bits);
pr_info("... generic registers: %d\n", x86_pmu.num_counters);
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index a6d91d4..da9047e 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3160,6 +3160,19 @@ err:
return -ENOMEM;
}
+static void flip_smm_bit(void *data)
+{
+ unsigned long set = *(unsigned long *)data;
+
+ if (set > 0) {
+ msr_set_bit(MSR_IA32_DEBUGCTLMSR,
+ DEBUGCTLMSR_FREEZE_IN_SMM_BIT);
+ } else {
+ msr_clear_bit(MSR_IA32_DEBUGCTLMSR,
+ DEBUGCTLMSR_FREEZE_IN_SMM_BIT);
+ }
+}
+
static void intel_pmu_cpu_starting(int cpu)
{
struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
@@ -3174,6 +3187,8 @@ static void intel_pmu_cpu_starting(int cpu)
cpuc->lbr_sel = NULL;
+ flip_smm_bit(&x86_pmu.attr_freeze_on_smi);
+
if (!cpuc->shared_regs)
return;
@@ -3595,6 +3610,52 @@ static struct attribute *hsw_events_attrs[] = {
NULL
};
+static ssize_t freeze_on_smi_show(struct device *cdev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%lu\n", x86_pmu.attr_freeze_on_smi);
+}
+
+static DEFINE_MUTEX(freeze_on_smi_mutex);
+
+static ssize_t freeze_on_smi_store(struct device *cdev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long val;
+ ssize_t ret;
+
+ ret = kstrtoul(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ if (val > 1)
+ return -EINVAL;
+
+ mutex_lock(&freeze_on_smi_mutex);
+
+ if (x86_pmu.attr_freeze_on_smi == val)
+ goto done;
+
+ x86_pmu.attr_freeze_on_smi = val;
+
+ get_online_cpus();
+ on_each_cpu(flip_smm_bit, &val, 1);
+ put_online_cpus();
+done:
+ mutex_unlock(&freeze_on_smi_mutex);
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(freeze_on_smi);
+
+static struct attribute *intel_pmu_attrs[] = {
+ &dev_attr_freeze_on_smi.attr,
+ NULL,
+};
+
__init int intel_pmu_init(void)
{
union cpuid10_edx edx;
@@ -3641,6 +3702,8 @@ __init int intel_pmu_init(void)
x86_pmu.max_pebs_events = min_t(unsigned, MAX_PEBS_EVENTS, x86_pmu.num_counters);
+
+ x86_pmu.attrs = intel_pmu_attrs;
/*
* Quirk: v2 perfmon does not report fixed-purpose events, so
* assume at least 3 events, when not running in a hypervisor:
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index be3d362..53728ee 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -562,6 +562,9 @@ struct x86_pmu {
ssize_t (*events_sysfs_show)(char *page, u64 config);
struct attribute **cpu_events;
+ unsigned long attr_freeze_on_smi;
+ struct attribute **attrs;
+
/*
* CPU Hotplug hooks
*/
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 673f9ac..18b1623 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -137,6 +137,8 @@
#define DEBUGCTLMSR_BTS_OFF_OS (1UL << 9)
#define DEBUGCTLMSR_BTS_OFF_USR (1UL << 10)
#define DEBUGCTLMSR_FREEZE_LBRS_ON_PMI (1UL << 11)
+#define DEBUGCTLMSR_FREEZE_IN_SMM_BIT 14
+#define DEBUGCTLMSR_FREEZE_IN_SMM (1UL << DEBUGCTLMSR_FREEZE_IN_SMM_BIT)
#define MSR_PEBS_FRONTEND 0x000003f7
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