diff --git a/[refs] b/[refs]
index 819a180f60eb..363ac4362456 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8fa938acb318378463987b04be083dc2467e0480
+refs/heads/master: 9855d8ce41a7801548a05d844db2f46c3e810166
diff --git a/trunk/drivers/acpi/processor_perflib.c b/trunk/drivers/acpi/processor_perflib.c
index 836bfe069042..53e7ac9403a7 100644
--- a/trunk/drivers/acpi/processor_perflib.c
+++ b/trunk/drivers/acpi/processor_perflib.c
@@ -340,6 +340,13 @@ static void amd_fixup_frequency(struct acpi_processor_px *px, int i)
 	if ((boot_cpu_data.x86 == 0x10 && boot_cpu_data.x86_model < 10)
 	    || boot_cpu_data.x86 == 0x11) {
 		rdmsr(MSR_AMD_PSTATE_DEF_BASE + index, lo, hi);
+		/*
+		 * MSR C001_0064+:
+		 * Bit 63: PstateEn. Read-write. If set, the P-state is valid.
+		 */
+		if (!(hi & BIT(31)))
+			return;
+
 		fid = lo & 0x3f;
 		did = (lo >> 6) & 7;
 		if (boot_cpu_data.x86 == 0x10)