commit a5ecda79870b41f5b2ee21975f0f1c931114d258
Author: sangamesh <sragate@vols.utk.edu>
Date:   Thu Jun 11 17:48:36 2015 -0400

    Thanks to William Cohen for the patch which does the following:
    Checking the cpu family and module number is not sufficient to determine
    whether RAPL can be used.  If the papi is running inside a guest VM,
    the MSR used by the PAPI RAPL component may not be available.  There
    should be a simple read test to verify the RAPL MSR registers are
    available.  This allows the component to more clearly report that RAPL
    is unsupported rather than just exiting program when the RAPL

diff --git a/src/components/rapl/linux-rapl.c b/src/components/rapl/linux-rapl.c
index f0d376e..8dff3fe 100644
--- a/src/components/rapl/linux-rapl.c
+++ b/src/components/rapl/linux-rapl.c
@@ -447,6 +447,13 @@ _rapl_init_component( int cidx )
         return PAPI_ESYS;
      }
 
+     /* Verify needed MSR is readable. In a guest VM it may not be readable*/
+     if (pread(fd, &result, sizeof result, MSR_RAPL_POWER_UNIT) != sizeof result ) {
+        strncpy(_rapl_vector.cmp_info.disabled_reason,
+               "Unable to access RAPL registers",PAPI_MAX_STR_LEN);
+        return PAPI_ESYS;
+     }
+
      /* Calculate the units used */
      result=read_msr(fd,MSR_RAPL_POWER_UNIT);