Revert of [telemetry] Read MSRs from a separate privileged process.

tools/telemetry/telemetry/core/platform/power_monitor/msr_power_monitor.py

Index: tools/telemetry/telemetry/core/platform/power_monitor/msr_power_monitor.py
diff --git a/tools/telemetry/telemetry/core/platform/power_monitor/msr_power_monitor.py b/tools/telemetry/telemetry/core/platform/power_monitor/msr_power_monitor.py
index 038346dfebad4fa71614f4f346a388ca514833f9..80b9f5f26838a4f67e879d172f7c0f0a2fbb27c1 100644
--- a/tools/telemetry/telemetry/core/platform/power_monitor/msr_power_monitor.py
+++ b/tools/telemetry/telemetry/core/platform/power_monitor/msr_power_monitor.py
@@ -2,12 +2,19 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import atexit
+import ctypes
 import logging
+import os
 import platform
 import re
+import sys
+import zipfile
 
 from telemetry import decorators
 from telemetry.core.platform import power_monitor
+from telemetry.util import cloud_storage
+from telemetry.util import path
 
 
 MSR_RAPL_POWER_UNIT = 0x606
@@ -17,6 +24,100 @@
 MSR_DRAM_ENERGY_STATUS = 0x619
 IA32_PACKAGE_THERM_STATUS = 0x1b1
 IA32_TEMPERATURE_TARGET = 0x1a2
+
+
+WINRING0_STATUS_MESSAGES = (
+    'No error',
+    'Unsupported platform',
+    'Driver not loaded. You may need to run as Administrator',
+    'Driver not found',
+    'Driver unloaded by other process',
+    'Driver not loaded because of executing on Network Drive',
+    'Unknown error',
+)
+
+
+# The DLL initialization is global, so put it in a global variable.
+_winring0 = None
+
+
+class WinRing0Error(OSError):
+  pass
+
+
+@decorators.Cache
+def WinRing0Path():
+  python_is_64_bit = sys.maxsize > 2 ** 32
+  win_binary_dir = os.path.join(path.GetTelemetryDir(), 'bin', 'win')
+  dll_file_name = 'WinRing0x64.dll' if python_is_64_bit else 'WinRing0.dll'
+  dll_path = os.path.join(win_binary_dir, dll_file_name)
+
+  os_is_64_bit = 'PROGRAMFILES(X86)' in os.environ
+  executable_dir = os.path.dirname(sys.executable)
+  driver_file_name = 'WinRing0x64.sys' if os_is_64_bit else 'WinRing0.sys'
+  driver_path = os.path.join(executable_dir, driver_file_name)
+
+  # Check for WinRing0 and download if needed.
+  if not (os.path.exists(dll_path) and os.path.exists(driver_path)):
+    zip_path = os.path.join(win_binary_dir, 'winring0.zip')
+    cloud_storage.GetIfChanged(zip_path, bucket=cloud_storage.PUBLIC_BUCKET)
+    try:
+      with zipfile.ZipFile(zip_path, 'r') as zip_file:
+        # Install DLL.
+        if not os.path.exists(dll_path):
+          zip_file.extract(dll_file_name, win_binary_dir)
+        # Install kernel driver.
+        if not os.path.exists(driver_path):
+          zip_file.extract(driver_file_name, executable_dir)
+    finally:
+      os.remove(zip_path)
+
+  return dll_path
+
+
+def _Initialize():
+  global _winring0
+  if not _winring0:
+    winring0 = ctypes.WinDLL(WinRing0Path())
+    if not winring0.InitializeOls():
+      winring0_status = winring0.GetDllStatus()
+      raise WinRing0Error(winring0_status,
+                          'Unable to initialize WinRing0: %s' %
+                          WINRING0_STATUS_MESSAGES[winring0_status])
+    _winring0 = winring0
+    atexit.register(_Deinitialize)
+
+
+def _Deinitialize():
+  global _winring0
+  if _winring0:
+    _winring0.DeinitializeOls()
+    _winring0 = None
+
+
+def _ReadMsr(msr_number):
+  low = ctypes.c_uint()
+  high = ctypes.c_uint()
+  _winring0.Rdmsr(ctypes.c_uint(msr_number),
+                  ctypes.byref(low), ctypes.byref(high))
+  return high.value << 32 | low.value
+
+
+@decorators.Cache
+def _EnergyMultiplier():
+  return 0.5 ** ((_ReadMsr(MSR_RAPL_POWER_UNIT) >> 8) & 0x1f)
+
+
+def _PackageEnergyJoules():
+  return _ReadMsr(MSR_PKG_ENERGY_STATUS) * _EnergyMultiplier()
+
+
+def _TemperatureCelsius():
+  tcc_activation_temp = _ReadMsr(IA32_TEMPERATURE_TARGET) >> 16 & 0x7f
+  if tcc_activation_temp <= 0:
+    tcc_activation_temp = 105
+  package_temp_headroom = _ReadMsr(IA32_PACKAGE_THERM_STATUS) >> 16 & 0x7f
+  return tcc_activation_temp - package_temp_headroom
 
 
 def _JoulesToMilliwattHours(value_joules):
@@ -48,15 +149,16 @@
       return False
 
     try:
-      if self._PackageEnergyJoules() <= 0:
-        logging.info('Cannot monitor power: no energy readings.')
-        return False
+      _Initialize()
+    except OSError:
+      return False
 
-      if self._TemperatureCelsius() <= 0:
-        logging.info('Cannot monitor power: no temperature readings.')
-        return False
-    except OSError as e:
-      logging.info('Cannot monitor power: %s' % e)
+    if _PackageEnergyJoules() <= 0:
+      logging.info('Cannot monitor power: no energy readings.')
+      return False
+
+    if _TemperatureCelsius() <= 0:
+      logging.info('Cannot monitor power: no temperature readings.')
       return False
 
     return True
@@ -64,15 +166,16 @@
   def StartMonitoringPower(self, browser):
     assert self._start_energy_j is None and self._start_temp_c is None, (
         'Called StartMonitoringPower() twice.')
-    self._start_energy_j = self._PackageEnergyJoules()
-    self._start_temp_c = self._TemperatureCelsius()
+    _Initialize()
+    self._start_energy_j = _PackageEnergyJoules()
+    self._start_temp_c = _TemperatureCelsius()
 
   def StopMonitoringPower(self):
     assert not(self._start_energy_j is None or self._start_temp_c is None), (
         'Called StopMonitoringPower() before StartMonitoringPower().')
 
-    energy_consumption_j = self._PackageEnergyJoules() - self._start_energy_j
-    average_temp_c = (self._TemperatureCelsius() + self._start_temp_c) / 2.
+    energy_consumption_j = _PackageEnergyJoules() - self._start_energy_j
+    average_temp_c = (_TemperatureCelsius() + self._start_temp_c) / 2.
     assert energy_consumption_j >= 0, ('Negative energy consumption. (Starting '
                                        'energy was %s.)' % self._start_energy_j)
 
@@ -88,20 +191,3 @@
             },
         },
     }
-
-  @decorators.Cache
-  def _EnergyMultiplier(self):
-    return 0.5 ** ((self._backend.ReadMsr(MSR_RAPL_POWER_UNIT) >> 8) & 0x1f)
-
-  def _PackageEnergyJoules(self):
-    return (self._backend.ReadMsr(MSR_PKG_ENERGY_STATUS) *
-            self._EnergyMultiplier())
-
-  def _TemperatureCelsius(self):
-    tcc_activation_temp = (
-        self._backend.ReadMsr(IA32_TEMPERATURE_TARGET) >> 16 & 0x7f)
-    if tcc_activation_temp <= 0:
-      tcc_activation_temp = 105
-    package_temp_headroom = (
-        self._backend.ReadMsr(IA32_PACKAGE_THERM_STATUS) >> 16 & 0x7f)
-    return tcc_activation_temp - package_temp_headroom