2 files changed, 31 insertions, 4 deletions

diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
index d3dcd58b87c..7f05f44b97e 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
@@ -115,9 +115,20 @@ static int query_current_values_with_pending_wait(struct powernow_k8_data *data)
 	u32 i = 0;
 
 	if (cpu_family == CPU_HW_PSTATE) {
-		rdmsr(MSR_PSTATE_STATUS, lo, hi);
-		i = lo & HW_PSTATE_MASK;
-		data->currpstate = i;
+		if (data->currpstate == HW_PSTATE_INVALID) {
+			/* read (initial) hw pstate if not yet set */
+			rdmsr(MSR_PSTATE_STATUS, lo, hi);
+			i = lo & HW_PSTATE_MASK;
+
+			/*
+			 * a workaround for family 11h erratum 311 might cause
+			 * an "out-of-range Pstate if the core is in Pstate-0
+			 */
+			if (i >= data->numps)
+				data->currpstate = HW_PSTATE_0;
+			else
+				data->currpstate = i;
+		}
 		return 0;
 	}
 	do {
@@ -1121,6 +1132,7 @@ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
 	}
 
 	data->cpu = pol->cpu;
+	data->currpstate = HW_PSTATE_INVALID;
 
 	if (powernow_k8_cpu_init_acpi(data)) {
 		/*
diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.h b/arch/x86/kernel/cpu/cpufreq/powernow-k8.h
index ab48cfed4d9..65cfb5d7f77 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.h
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.h
@@ -5,6 +5,19 @@
  *  http://www.gnu.org/licenses/gpl.html
  */
 
+
+enum pstate {
+	HW_PSTATE_INVALID = 0xff,
+	HW_PSTATE_0 = 0,
+	HW_PSTATE_1 = 1,
+	HW_PSTATE_2 = 2,
+	HW_PSTATE_3 = 3,
+	HW_PSTATE_4 = 4,
+	HW_PSTATE_5 = 5,
+	HW_PSTATE_6 = 6,
+	HW_PSTATE_7 = 7,
+};
+
 struct powernow_k8_data {
 	unsigned int cpu;
 
@@ -23,7 +36,9 @@ struct powernow_k8_data {
         u32 exttype; /* extended interface = 1 */
 
 	/* keep track of the current fid / vid or pstate */
-	u32 currvid, currfid, currpstate;
+	u32 currvid;
+	u32 currfid;
+	enum pstate currpstate;
 
 	/* the powernow_table includes all frequency and vid/fid pairings:
 	 * fid are the lower 8 bits of the index, vid are the upper 8 bits.