[Fuchsia] Replace no-kvm flag with allow-no-kvm.

Remove require_kvm arg from GetDeploymentTargetForArgs.
Replace useless no-kvm flag with allow-no-kvm.

Bug: 1000906
Change-Id: I6d85d351e4089384721d85f697909b4d9280fe53
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2071136
Commit-Queue: Chong Gu <chonggu@google.com>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744367}

build/fuchsia/common_args.py

@@ -78,10 +78,11 @@ def AddCommonArgs(arg_parser):
   common_args.add_argument('--memory', type=int, default=2048,
                            help='Sets the RAM size (MB) if launching in a VM'),
   common_args.add_argument(
-      '--no-kvm',
-      action='store_true',
-      default=False,
-      help='Disable KVM virtualization.')
+      '--allow-no-kvm',
+      action='store_false',
+      dest='require_kvm',
+      default=True,
+      help='Do not require KVM acceleration for emulators.')
   common_args.add_argument(
       '--os_check', choices=['check', 'update', 'ignore'],
       default='update',
@@ -120,7 +121,7 @@ def ConfigureLogging(args):
       logging.DEBUG if args.verbose else logging.WARN)
 
 
-def GetDeploymentTargetForArgs(args, require_kvm=False):
+def GetDeploymentTargetForArgs(args):
   """Constructs a deployment target object using parameters taken from
   command line arguments."""
   if args.system_log_file == '-':
@@ -150,10 +151,12 @@ def GetDeploymentTargetForArgs(args, require_kvm=False):
                          'os_check':args.os_check })
     return DeviceTarget(**target_args)
   else:
-    target_args.update({ 'cpu_cores':args.qemu_cpu_cores,
-                         'require_kvm':not args.no_kvm,
-                         'emu_type':args.device,
-                         'ram_size_mb':args.memory })
+    target_args.update({
+        'cpu_cores': args.qemu_cpu_cores,
+        'require_kvm': args.require_kvm,
+        'emu_type': args.device,
+        'ram_size_mb': args.memory
+    })
     if args.device == 'qemu':
       return QemuTarget(**target_args)
     else:

build/fuchsia/qemu_target.py

@@ -20,6 +20,7 @@ import tempfile
 from common import GetHostArchFromPlatform, GetEmuRootForPlatform
 from common import EnsurePathExists
 from qemu_image import ExecQemuImgWithRetry
+from target import FuchsiaTargetException
 
 
 # Virtual networking configuration data for QEMU.
@@ -46,13 +47,16 @@ class QemuTarget(emu_target.EmuTarget):
     return self._emu_type
 
   def _IsKvmEnabled(self):
-    if self._require_kvm:
-      if (sys.platform.startswith('linux') and
-          os.access('/dev/kvm', os.R_OK | os.W_OK)):
-        if self._target_cpu == 'arm64' and platform.machine() == 'aarch64':
-          return True
-        if self._target_cpu == 'x64' and platform.machine() == 'x86_64':
+    kvm_supported = sys.platform.startswith('linux') and \
+                    os.access('/dev/kvm', os.R_OK | os.W_OK)
+    same_arch = \
+        (self._target_cpu == 'arm64' and platform.machine() == 'aarch64') or \
+        (self._target_cpu == 'x64' and platform.machine() == 'x86_64')
+    if kvm_supported and same_arch:
       return True
+    elif self._require_kvm:
+      raise FuchsiaTargetException('KVM required but unavailable.')
+    else:
       return False
 
   def _BuildQemuConfig(self):
@@ -210,5 +214,3 @@ def _EnsureBlobstoreQcowAndReturnPath(output_dir, target_arch):
     blobstore_hash_file.write(current_blobstore_hash)
 
   return qcow_path
-
-

build/fuchsia/test_runner.py

@@ -116,10 +116,7 @@ def main():
   if args.child_args:
     child_args.extend(args.child_args)
 
-  # KVM is required on x64 test bots.
-  require_kvm = args.test_launcher_bot_mode and args.target_cpu == 'x64'
-
-  with GetDeploymentTargetForArgs(args, require_kvm=require_kvm) as target:
+  with GetDeploymentTargetForArgs(args) as target:
     target.Start()
 
     if args.test_launcher_filter_file: