build/android/install_emulator_deps.py: run kvm-ok as root when needed.

build/android/install_emulator_deps.py

 #!/usr/bin/env python
 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Installs deps for using SDK emulator for testing.
 
 The script will download the SDK and system images, if they are not present, and
 install and enable KVM, if virtualization has been enabled in the BIOS.
 """
@@ skipping 76 matching lines @@
     True if sdk/system-images/android-<api_level>/x86 exists inside
     EMULATOR_SDK_ROOT.
   """
   api_target = 'android-%d' % api_level
   return os.path.exists(os.path.join(constants.EMULATOR_SDK_ROOT,
                                      'sdk', 'system-images',
                                      api_target, 'x86'))
 
 
 def CheckKVM():
-  """Check if KVM is enabled.
+  """Quickly check whether KVM is enabled.
 
   Returns:
-    True if kvm-ok returns 0 (already enabled)
+    True iff /dev/kvm exists (Linux only).
+  """
+  return os.path.exists('/dev/kvm')
+
+
+def RunKvmOk():
+  """Run kvm-ok as root to check that KVM is properly enabled after installation
+     of the required packages.
+
+  Returns:
+    True iff KVM is enabled (/dev/kvm exists). On failure, returns False
+    but also print detailed information explaining why KVM isn't enabled
+    (e.g. CPU doesn't support it, or BIOS disabled it).
   """
   try:
-    return not cmd_helper.RunCmd(['kvm-ok'])
+    # Note: kvm-ok is in /usr/sbin, so always use 'sudo' to run it.
+    return not cmd_helper.RunCmd(['sudo', 'kvm-ok'])
   except OSError:
     logging.info('kvm-ok not installed')
     return False
 
 
 def GetSDK():
   """Download the SDK and unzip it into EMULATOR_SDK_ROOT."""
   logging.info('Download Android SDK.')
   sdk_url = '%s/%s' % (SDK_BASE_URL, SDK_ZIP)
   try:
@@ skipping 14 matching lines @@
 def InstallKVM():
   """Installs KVM packages."""
   rc = cmd_helper.RunCmd(['sudo', 'apt-get', 'install', 'kvm'])
   if rc:
     logging.critical('ERROR: Did not install KVM. Make sure hardware '
                      'virtualization is enabled in BIOS (i.e. Intel VT-x or '
                      'AMD SVM).')
   # TODO(navabi): Use modprobe kvm-amd on AMD processors.
   rc = cmd_helper.RunCmd(['sudo', 'modprobe', 'kvm-intel'])
   if rc:
-    logging.critical('ERROR: Did not add KVM module to Linux Kernal. Make sure '
+    logging.critical('ERROR: Did not add KVM module to Linux Kernel. Make sure '
                      'hardware virtualization is enabled in BIOS.')
   # Now check to ensure KVM acceleration can be used.
-  rc = cmd_helper.RunCmd(['kvm-ok'])
-  if rc:
+  if not RunKvmOk():
     logging.critical('ERROR: Can not use KVM acceleration. Make sure hardware '
                      'virtualization is enabled in BIOS (i.e. Intel VT-x or '
                      'AMD SVM).')
 
 
 def GetX86Image(api_level=DEFAULT_ANDROID_API_LEVEL):
   """Download x86 system image from Intel's website.
 
   Args:
     api_level: the Android API level to download for.
@@ skipping 100 matching lines @@
 
   # Make sure KVM packages are installed and enabled.
   if CheckKVM():
     logging.info('KVM already installed and enabled.')
   else:
     InstallKVM()
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))