diff --git a/tests/vm/basevm.py b/tests/vm/basevm.py
index db479a65fd..97c6f625c9 100644
--- a/tests/vm/basevm.py
+++ b/tests/vm/basevm.py
@@ -30,15 +30,39 @@ import shutil
 import multiprocessing
 import traceback
 
-SSH_KEY = open(os.path.join(os.path.dirname(__file__),
-               "..", "keys", "id_rsa")).read()
-SSH_PUB_KEY = open(os.path.join(os.path.dirname(__file__),
-                   "..", "keys", "id_rsa.pub")).read()
-
+SSH_KEY_FILE = os.path.join(os.path.dirname(__file__),
+               "..", "keys", "id_rsa")
+SSH_PUB_KEY_FILE = os.path.join(os.path.dirname(__file__),
+                   "..", "keys", "id_rsa.pub")
+
+# This is the standard configuration.
+# Any or all of these can be overridden by
+# passing in a config argument to the VM constructor.
+DEFAULT_CONFIG = {
+    'cpu'             : "max",
+    'machine'         : 'pc',
+    'guest_user'      : "qemu",
+    'guest_pass'      : "qemupass",
+    'root_pass'       : "qemupass",
+    'ssh_key_file'    : SSH_KEY_FILE,
+    'ssh_pub_key_file': SSH_PUB_KEY_FILE,
+    'memory'          : "4G",
+    'extra_args'      : [],
+    'qemu_args'       : "",
+    'dns'             : "",
+    'ssh_port'        : 0,
+    'install_cmds'    : "",
+    'boot_dev_type'   : "block",
+    'ssh_timeout'     : 1,
+}
+BOOT_DEVICE = {
+    'block' :  "-drive file={},if=none,id=drive0,cache=writeback "\
+               "-device virtio-blk,drive=drive0,bootindex=0",
+    'scsi'  :  "-device virtio-scsi-device,id=scsi "\
+               "-drive file={},format=raw,if=none,id=hd0 "\
+               "-device scsi-hd,drive=hd0,bootindex=0",
+}
 class BaseVM(object):
-    GUEST_USER = "qemu"
-    GUEST_PASS = "qemupass"
-    ROOT_PASS = "qemupass"
 
     envvars = [
         "https_proxy",
@@ -61,19 +85,30 @@ class BaseVM(object):
     # 4 is arbitrary, but greater than 2,
     # since we found we need to wait more than twice as long.
     tcg_ssh_timeout_multiplier = 4
-    def __init__(self, debug=False, vcpus=None):
+    def __init__(self, debug=False, vcpus=None, config=None):
         self._guest = None
+        # Allow input config to override defaults.
+        self._config = DEFAULT_CONFIG.copy()
+        if config != None:
+            self._config.update(config)
+        self.validate_ssh_keys()
         self._tmpdir = os.path.realpath(tempfile.mkdtemp(prefix="vm-test-",
                                                          suffix=".tmp",
                                                          dir="."))
         atexit.register(shutil.rmtree, self._tmpdir)
-
-        self._ssh_key_file = os.path.join(self._tmpdir, "id_rsa")
-        open(self._ssh_key_file, "w").write(SSH_KEY)
-        subprocess.check_call(["chmod", "600", self._ssh_key_file])
-
-        self._ssh_pub_key_file = os.path.join(self._tmpdir, "id_rsa.pub")
-        open(self._ssh_pub_key_file, "w").write(SSH_PUB_KEY)
+        # Copy the key files to a temporary directory.
+        # Also chmod the key file to agree with ssh requirements.
+        self._config['ssh_key'] = \
+            open(self._config['ssh_key_file']).read().rstrip()
+        self._config['ssh_pub_key'] = \
+            open(self._config['ssh_pub_key_file']).read().rstrip()
+        self._ssh_tmp_key_file = os.path.join(self._tmpdir, "id_rsa")
+        open(self._ssh_tmp_key_file, "w").write(self._config['ssh_key'])
+        subprocess.check_call(["chmod", "600", self._ssh_tmp_key_file])
+
+        self._ssh_tmp_pub_key_file = os.path.join(self._tmpdir, "id_rsa.pub")
+        open(self._ssh_tmp_pub_key_file,
+             "w").write(self._config['ssh_pub_key'])
 
         self.debug = debug
         self._stderr = sys.stderr
@@ -82,11 +117,14 @@ class BaseVM(object):
             self._stdout = sys.stdout
         else:
             self._stdout = self._devnull
+        netdev = "user,id=vnet,hostfwd=:127.0.0.1:{}-:22"
         self._args = [ \
-            "-nodefaults", "-m", "4G",
-            "-cpu", "max",
-            "-netdev", "user,id=vnet,hostfwd=:127.0.0.1:0-:22" +
-                       (",ipv6=no" if not self.ipv6 else ""),
+            "-nodefaults", "-m", self._config['memory'],
+            "-cpu", self._config['cpu'],
+            "-netdev",
+            netdev.format(self._config['ssh_port']) +
+            (",ipv6=no" if not self.ipv6 else "") +
+            (",dns=" + self._config['dns'] if self._config['dns'] else ""),
             "-device", "virtio-net-pci,netdev=vnet",
             "-vnc", "127.0.0.1:0,to=20"]
         if vcpus and vcpus > 1:
@@ -97,6 +135,45 @@ class BaseVM(object):
             logging.info("KVM not available, not using -enable-kvm")
         self._data_args = []
 
+        if self._config['qemu_args'] != None:
+            qemu_args = self._config['qemu_args']
+            qemu_args = qemu_args.replace('\n',' ').replace('\r','')
+            # Remove any empty strings from list.
+            self._config['extra_args'] = [x for x in qemu_args.split(' ') if x]
+
+    def validate_ssh_keys(self):
+        """Check to see if the ssh key files exist."""
+        if 'ssh_key_file' not in self._config or\
+           not os.path.exists(self._config['ssh_key_file']):
+            raise Exception("ssh key file not found.")
+        if 'ssh_pub_key_file' not in self._config or\
+           not os.path.exists(self._config['ssh_pub_key_file']):
+               raise Exception("ssh pub key file not found.")
+
+    def wait_boot(self, wait_string=None):
+        """Wait for the standard string we expect
+           on completion of a normal boot.
+           The user can also choose to override with an
+           alternate string to wait for."""
+        if wait_string is None:
+            if self.login_prompt is None:
+                raise Exception("self.login_prompt not defined")
+            wait_string = self.login_prompt
+        # Intentionally bump up the default timeout under TCG,
+        # since the console wait below takes longer.
+        timeout = self.socket_timeout
+        if not kvm_available(self.arch):
+            timeout *= 8
+        self.console_init(timeout=timeout)
+        self.console_wait(wait_string)
+
+    def __getattr__(self, name):
+        # Support direct access to config by key.
+        # for example, access self._config['cpu'] by self.cpu
+        if name.lower() in self._config.keys():
+            return self._config[name.lower()]
+        return object.__getattribute__(self, name)
+
     def _download_with_cache(self, url, sha256sum=None, sha512sum=None):
         def check_sha256sum(fname):
             if not sha256sum:
@@ -128,8 +205,9 @@ class BaseVM(object):
                    "-t",
                    "-o", "StrictHostKeyChecking=no",
                    "-o", "UserKnownHostsFile=" + os.devnull,
-                   "-o", "ConnectTimeout=1",
-                   "-p", self.ssh_port, "-i", self._ssh_key_file]
+                   "-o",
+                   "ConnectTimeout={}".format(self._config["ssh_timeout"]),
+                   "-p", self.ssh_port, "-i", self._ssh_tmp_key_file]
         # If not in debug mode, set ssh to quiet mode to
         # avoid printing the results of commands.
         if not self.debug:
@@ -178,15 +256,15 @@ class BaseVM(object):
                             "virtio-blk,drive=%s,serial=%s,bootindex=1" % (name, name)]
 
     def boot(self, img, extra_args=[]):
-        args = self._args + [
-            "-device", "VGA",
-            "-drive", "file=%s,if=none,id=drive0,cache=writeback" % img,
-            "-device", "virtio-blk,drive=drive0,bootindex=0"]
-        args += self._data_args + extra_args
+        boot_dev = BOOT_DEVICE[self._config['boot_dev_type']]
+        boot_params = boot_dev.format(img)
+        args = self._args + boot_params.split(' ')
+        args += self._data_args + extra_args + self._config['extra_args']
+        args += ["-device", "VGA"]
         logging.debug("QEMU args: %s", " ".join(args))
         qemu_bin = os.environ.get("QEMU", "qemu-system-" + self.arch)
         guest = QEMUMachine(binary=qemu_bin, args=args)
-        guest.set_machine('pc')
+        guest.set_machine(self._config['machine'])
         guest.set_console()
         try:
             guest.launch()
@@ -294,7 +372,8 @@ class BaseVM(object):
         self.console_send(command)
 
     def console_ssh_init(self, prompt, user, pw):
-        sshkey_cmd = "echo '%s' > .ssh/authorized_keys\n" % SSH_PUB_KEY.rstrip()
+        sshkey_cmd = "echo '%s' > .ssh/authorized_keys\n" \
+                     % self._config['ssh_pub_key'].rstrip()
         self.console_wait_send("login:",    "%s\n" % user)
         self.console_wait_send("Password:", "%s\n" % pw)
         self.console_wait_send(prompt,      "mkdir .ssh\n")
@@ -353,23 +432,23 @@ class BaseVM(object):
                           "local-hostname: {}-guest\n".format(name)])
         mdata.close()
         udata = open(os.path.join(cidir, "user-data"), "w")
-        print("guest user:pw {}:{}".format(self.GUEST_USER,
-                                           self.GUEST_PASS))
+        print("guest user:pw {}:{}".format(self._config['guest_user'],
+                                           self._config['guest_pass']))
         udata.writelines(["#cloud-config\n",
                           "chpasswd:\n",
                           "  list: |\n",
-                          "    root:%s\n" % self.ROOT_PASS,
-                          "    %s:%s\n" % (self.GUEST_USER,
-                                           self.GUEST_PASS),
+                          "    root:%s\n" % self._config['root_pass'],
+                          "    %s:%s\n" % (self._config['guest_user'],
+                                           self._config['guest_pass']),
                           "  expire: False\n",
                           "users:\n",
-                          "  - name: %s\n" % self.GUEST_USER,
+                          "  - name: %s\n" % self._config['guest_user'],
                           "    sudo: ALL=(ALL) NOPASSWD:ALL\n",
                           "    ssh-authorized-keys:\n",
-                          "    - %s\n" % SSH_PUB_KEY.rstrip(),
+                          "    - %s\n" % self._config['ssh_pub_key'],
                           "  - name: root\n",
                           "    ssh-authorized-keys:\n",
-                          "    - %s\n" % SSH_PUB_KEY.rstrip(),
+                          "    - %s\n" % self._config['ssh_pub_key'],
                           "locale: en_US.UTF-8\n"])
         proxy = os.environ.get("http_proxy")
         if not proxy is None:
@@ -422,15 +501,17 @@ def parse_args(vmcls):
     parser.disable_interspersed_args()
     return parser.parse_args()
 
-def main(vmcls):
+def main(vmcls, config=None):
     try:
+        if config == None:
+            config = {}
         args, argv = parse_args(vmcls)
         if not argv and not args.build_qemu and not args.build_image:
             print("Nothing to do?")
             return 1
         logging.basicConfig(level=(logging.DEBUG if args.debug
                                    else logging.WARN))
-        vm = vmcls(debug=args.debug, vcpus=args.jobs)
+        vm = vmcls(debug=args.debug, vcpus=args.jobs, config=config)
         if args.build_image:
             if os.path.exists(args.image) and not args.force:
                 sys.stderr.writelines(["Image file exists: %s\n" % args.image,
