OcCpuLib: Support fallback frequency

Include/Library/OcCpuLib.h

@@ -18,6 +18,11 @@
 #include <IndustryStandard/CpuId.h>
 #include <IndustryStandard/AppleIntelCpuInfo.h>
 
+/**
+  Assumed CPU frequency when it cannot be detected.
+**/
+#define OC_FALLBACK_CPU_FREQUENCY 1000000000
+
 typedef struct {
   //
   // Note, Vendor and BrandString are reordered for proper alignment.
@@ -182,7 +187,7 @@ OcCpuGetGeneration (
 /**
   Obtain CPU's invariant TSC frequency.
 
-  @retval CPU's TSC frequency.
+  @retval CPU's TSC frequency or OC_FALLBACK_CPU_FREQUENCY.
 **/
 UINT64
 OcGetTSCFrequency (

Library/OcCpuLib/FrequencyDetect.c

@@ -484,6 +484,12 @@ OcGetTSCFrequency (
     CPUFrequency = InternalCalculateVMTFrequency (NULL, NULL);
     if (CPUFrequency == 0) {
       CPUFrequency = InternalCalculateTSCFromPMTimer (FALSE);
+      if (CPUFrequency == 0) {
+        //
+        // Assume at least some frequency, so that we always work.
+        //
+        CPUFrequency = OC_FALLBACK_CPU_FREQUENCY;
+      }
     }
   }
   //