From: Maria Dimakopoulou <maria.n.dimakopou...@gmail.com>
This patch adds a sysfs entry:
/sys/devices/cpu/ht_bug_workaround
to activate/deactivate the PMU HT bug workaround.
To activate (activated by default):
# echo 1 > /sys/devices/cpu/ht_bug_workaround
To deactivate:
# echo 0 > /sys/devices/cpu/ht_bug_workaround
Results effective only once there is no more active
events.
Reviewed-by: Stephane Eranian <eran...@google.com>
Signed-off-by: Maria Dimakopoulou <maria.n.dimakopou...@gmail.com>
---
arch/x86/kernel/cpu/perf_event.c | 44 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 2d5e7a9..5a5515e 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1881,10 +1881,54 @@ static ssize_t set_attr_rdpmc(struct device *cdev,
return count;
}
+static ssize_t get_attr_xsu(struct device *cdev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ff = is_ht_workaround_enabled();
+
+ return snprintf(buf, 40, "%d\n", ff);
+}
+
+static ssize_t set_attr_xsu(struct device *cdev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs;
+ unsigned long val;
+ unsigned long flags;
+ int ff = is_ht_workaround_enabled();
+ ssize_t ret;
+
+ /*
+ * if workaround, disabled, no effect
+ */
+ if (!excl_cntrs)
+ return count;
+
+ ret = kstrtoul(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ spin_lock_irqsave(&excl_cntrs->lock, flags);
+ if (!!val != ff) {
+ if (!val)
+ x86_pmu.flags &= ~PMU_FL_EXCL_ENABLED;
+ else
+ x86_pmu.flags |= PMU_FL_EXCL_ENABLED;
+ }
+ spin_unlock_irqrestore(&excl_cntrs->lock, flags);
+ return count;
+}
+
static DEVICE_ATTR(rdpmc, S_IRUSR | S_IWUSR, get_attr_rdpmc, set_attr_rdpmc);
+static DEVICE_ATTR(ht_bug_workaround, S_IRUSR | S_IWUSR, get_attr_xsu,
+ set_attr_xsu);
static struct attribute *x86_pmu_attrs[] = {
&dev_attr_rdpmc.attr,
+ &dev_attr_ht_bug_workaround.attr,
NULL,
};
--
1.9.1
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