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

tools/telemetry/telemetry/core/platform/win_platform_backend.py

Index: tools/telemetry/telemetry/core/platform/win_platform_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/win_platform_backend.py b/tools/telemetry/telemetry/core/platform/win_platform_backend.py
index a3ef7de41bf7235461dce0ea6a06aa28794b496e..6e91b3a91beae84d4966a64eca143a4c9afeb465 100644
--- a/tools/telemetry/telemetry/core/platform/win_platform_backend.py
+++ b/tools/telemetry/telemetry/core/platform/win_platform_backend.py
@@ -2,28 +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 collections
 import contextlib
 import ctypes
-import os
 import platform
 import re
-import socket
-import struct
 import subprocess
-import sys
 import time
-import zipfile
 
 from telemetry import decorators
 from telemetry.core import exceptions
-from telemetry.core import util
 from telemetry.core.platform import desktop_platform_backend
 from telemetry.core.platform import platform_backend
 from telemetry.core.platform.power_monitor import msr_power_monitor
-from telemetry.util import cloud_storage
-from telemetry.util import path
 
 try:
   import pywintypes  # pylint: disable=F0401
@@ -43,34 +34,6 @@
   win32security = None
 
 
-def _InstallWinRing0():
-  """WinRing0 is used for reading MSRs."""
-  executable_dir = os.path.dirname(sys.executable)
-
-  python_is_64_bit = sys.maxsize > 2 ** 32
-  dll_file_name = 'WinRing0x64.dll' if python_is_64_bit else 'WinRing0.dll'
-  dll_path = os.path.join(executable_dir, dll_file_name)
-
-  os_is_64_bit = 'PROGRAMFILES(X86)' in os.environ
-  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)):
-    win_binary_dir = os.path.join(path.GetTelemetryDir(), 'bin', 'win')
-    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, executable_dir)
-        # Install kernel driver.
-        if not os.path.exists(driver_path):
-          zip_file.extract(driver_file_name, executable_dir)
-    finally:
-      os.remove(zip_path)
-
 
 def IsCurrentProcessElevated():
   handle = win32process.GetCurrentProcess()
@@ -80,34 +43,10 @@
         win32security.GetTokenInformation(token, win32security.TokenElevation))
 
 
-def TerminateProcess(process_handle):
-  if not process_handle:
-    return
-  if win32process.GetExitCodeProcess(process_handle) == win32con.STILL_ACTIVE:
-    win32process.TerminateProcess(process_handle, 0)
-  process_handle.close()
-
-
 class WinPlatformBackend(desktop_platform_backend.DesktopPlatformBackend):
   def __init__(self):
     super(WinPlatformBackend, self).__init__()
-    self._msr_server_handle = None
-    self._msr_server_port = None
     self._power_monitor = msr_power_monitor.MsrPowerMonitor(self)
-
-  def __del__(self):
-    self.close()
-
-  def close(self):
-    self.CloseMsrServer()
-
-  def CloseMsrServer(self):
-    if not self._msr_server_handle:
-      return
-
-    TerminateProcess(self._msr_server_handle)
-    self._msr_server_handle = None
-    self._msr_server_port = None
 
   # pylint: disable=W0613
   def StartRawDisplayFrameRateMeasurement(self):
@@ -320,38 +259,3 @@
 
   def StopMonitoringPower(self):
     return self._power_monitor.StopMonitoringPower()
-
-  def _StartMsrServerIfNeeded(self):
-    if self._msr_server_handle:
-      return
-
-    _InstallWinRing0()
-    self._msr_server_port = util.GetUnreservedAvailableLocalPort()
-    # It might be flaky to get a port number without reserving it atomically,
-    # but if the server process chooses a port, we have no way of getting it.
-    # The stdout of the elevated process isn't accessible.
-    parameters = (
-        os.path.join(os.path.dirname(__file__), 'msr_server_win.py'),
-        str(self._msr_server_port),
-    )
-    self._msr_server_handle = self.LaunchApplication(
-        sys.executable, parameters, elevate_privilege=True)
-    # Wait for server to start. connect has a default timeout of 1 second.
-    try:
-      socket.create_connection(('127.0.0.1', self._msr_server_port)).close()
-    except socket.error:
-      self.CloseMsrServer()
-    atexit.register(TerminateProcess, self._msr_server_handle)
-
-  def ReadMsr(self, msr_number):
-    self._StartMsrServerIfNeeded()
-    if not self._msr_server_handle:
-      raise OSError('Unable to start MSR server.')
-
-    sock = socket.create_connection(('127.0.0.1', self._msr_server_port), 0.1)
-    try:
-      sock.sendall(struct.pack('I', msr_number))
-      response = sock.recv(8)
-    finally:
-      sock.close()
-    return struct.unpack('Q', response)[0]