+static void _cpb_toggle_msrs(bool t)
+{
+ int cpu;
+
+ get_online_cpus();
+
+ rdmsr_on_cpus(cpu_online_mask, MSR_K7_HWCR, msrs);
+
+ for_each_cpu(cpu, cpu_online_mask) {
+ struct msr *reg = per_cpu_ptr(msrs, cpu);
+ if (t)
+ reg->l &= ~BIT(25);
+ else
+ reg->l |= BIT(25);
+ }
+ wrmsr_on_cpus(cpu_online_mask, MSR_K7_HWCR, msrs);
+
+ put_online_cpus();
+}
+
+/*
+ * Switch on/off core performance boosting.
+ *
+ * 0=disable
+ * 1=enable.
+ */
+static void cpb_toggle(bool t)
+{
+ if (!cpb_capable)
+ return;
+
+ if (t && !cpb_enabled) {
+ cpb_enabled = true;
+ _cpb_toggle_msrs(t);
+ printk(KERN_INFO PFX "Core Boosting enabled.\n");
+ } else if (!t && cpb_enabled) {
+ cpb_enabled = false;
+ _cpb_toggle_msrs(t);
+ printk(KERN_INFO PFX "Core Boosting disabled.\n");
+ }
+}
+
+static ssize_t store_cpb(struct cpufreq_policy *policy, const char *buf,
+ size_t count)
+{
+ int ret = -EINVAL;
+ unsigned long val = 0;
+
+ ret = strict_strtoul(buf, 10, &val);
+ if (!ret && (val == 0 || val == 1) && cpb_capable)
+ cpb_toggle(val);
+ else
+ return -EINVAL;
+
+ return count;
+}
+
+static ssize_t show_cpb(struct cpufreq_policy *policy, char *buf)
+{
+ return sprintf(buf, "%u\n", cpb_enabled);
+}
+
+#define define_one_rw(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0644, show_##_name, store_##_name)
+
+define_one_rw(cpb);
+