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 d3dcd58b87cd..7f05f44b97e9 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 ab48cfed4d96..65cfb5d7f77f 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.