testimage: allow using kvm when running qemux86* machines

Using kvm can provide significant speedups when running qemux86* machines
on an x86* host. Enabled by using the new QEMU_USE_KVM variable.

[YOCTO #9298]

(From OE-Core rev: ebac2c8d1fcd09ebce0659a4abb445e4f1c18571)

Signed-off-by: Bill Randle <william.c.randle@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/qemurunner.py

@@ -29,7 +29,7 @@ re_control_char = re.compile('[%s]' % re.escape("".join(control_chars)))
 
 class QemuRunner:
 
-    def __init__(self, machine, rootfs, display, tmpdir, deploy_dir_image, logfile, boottime, dump_dir, dump_host_cmds):
+    def __init__(self, machine, rootfs, display, tmpdir, deploy_dir_image, logfile, boottime, dump_dir, dump_host_cmds, use_kvm):
 
         # Popen object for runqemu
         self.runqemu = None
@@ -49,6 +49,7 @@ class QemuRunner:
         self.boottime = boottime
         self.logged = False
         self.thread = None
+        self.use_kvm = use_kvm
 
         self.runqemutime = 60
         self.host_dumper = HostDumper(dump_host_cmds, dump_dir)
@@ -133,7 +134,13 @@ class QemuRunner:
         self.origchldhandler = signal.getsignal(signal.SIGCHLD)
         signal.signal(signal.SIGCHLD, self.handleSIGCHLD)
 
-        launch_cmd = 'runqemu tcpserial=%s %s %s %s' % (self.serverport, self.machine, self.rootfs, self.qemuparams)
+        launch_cmd = 'runqemu '
+        if self.use_kvm:
+            logger.info('Using kvm for runqemu')
+            launch_cmd += 'kvm '
+        else:
+            logger.info('Not using kvm for runqemu')
+        launch_cmd += 'tcpserial=%s %s %s %s' % (self.serverport, self.machine, self.rootfs, self.qemuparams)
         # FIXME: We pass in stdin=subprocess.PIPE here to work around stty
         # blocking at the end of the runqemu script when using this within
         # oe-selftest (this makes stty error out immediately). There ought