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Diffstat (limited to 'arch/x86/kernel/cpu/umwait.c')
-rw-r--r--arch/x86/kernel/cpu/umwait.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/umwait.c b/arch/x86/kernel/cpu/umwait.c
index 56149d630e35..6a204e7336c1 100644
--- a/arch/x86/kernel/cpu/umwait.c
+++ b/arch/x86/kernel/cpu/umwait.c
@@ -131,8 +131,44 @@ static ssize_t enable_c02_store(struct device *dev,
}
static DEVICE_ATTR_RW(enable_c02);
+static ssize_t
+max_time_show(struct device *kobj, struct device_attribute *attr, char *buf)
+{
+ u32 ctrl = READ_ONCE(umwait_control_cached);
+
+ return sprintf(buf, "%u\n", umwait_ctrl_max_time(ctrl));
+}
+
+static ssize_t max_time_store(struct device *kobj,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ u32 max_time, ctrl;
+ int ret;
+
+ ret = kstrtou32(buf, 0, &max_time);
+ if (ret)
+ return ret;
+
+ /* bits[1:0] must be zero */
+ if (max_time & ~MSR_IA32_UMWAIT_CONTROL_TIME_MASK)
+ return -EINVAL;
+
+ mutex_lock(&umwait_lock);
+
+ ctrl = READ_ONCE(umwait_control_cached);
+ if (max_time != umwait_ctrl_max_time(ctrl))
+ umwait_update_control(max_time, umwait_ctrl_c02_enabled(ctrl));
+
+ mutex_unlock(&umwait_lock);
+
+ return count;
+}
+static DEVICE_ATTR_RW(max_time);
+
static struct attribute *umwait_attrs[] = {
&dev_attr_enable_c02.attr,
+ &dev_attr_max_time.attr,
NULL
};