[CPUFREQ] Create a blacklist for processors that should not load the …

…acpi-cpufreq module.

Create a blacklist for processors that should not load the acpi-cpufreq module.

The initial entry in the blacklist function is the Intel 0f68 processor.  It's
specification update mentions errata AL30 which implies that cpufreq should not
run on this processor.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Dave Jones <davej@redhat.com>

arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c

@@ -588,6 +588,21 @@ static const struct dmi_system_id sw_any_bug_dmi_table[] = {
 	},
 	{ }
 };
+
+static int acpi_cpufreq_blacklist(struct cpuinfo_x86 *c)
+{
+	/* http://www.intel.com/Assets/PDF/specupdate/314554.pdf
+	 * AL30: A Machine Check Exception (MCE) Occurring during an
+	 * Enhanced Intel SpeedStep Technology Ratio Change May Cause
+	 * Both Processor Cores to Lock Up when HT is enabled*/
+	if (c->x86_vendor == X86_VENDOR_INTEL) {
+		if ((c->x86 == 15) &&
+		    (c->x86_model == 6) &&
+		    (c->x86_mask == 8) && smt_capable())
+			return -ENODEV;
+		}
+	return 0;
+}
 #endif
 
 static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
@@ -602,6 +617,12 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 	dprintk("acpi_cpufreq_cpu_init\n");
 
+#ifdef CONFIG_SMP
+	result = acpi_cpufreq_blacklist(c);
+	if (result)
+		return result;
+#endif
+
 	data = kzalloc(sizeof(struct acpi_cpufreq_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;