diff --git a/tests/vm/basevm.py b/tests/vm/basevm.py
index ec92c8f105..08a8989ac0 100755
--- a/tests/vm/basevm.py
+++ b/tests/vm/basevm.py
@@ -31,6 +31,7 @@ import tempfile
 import shutil
 import multiprocessing
 import traceback
+import yaml
 
 SSH_KEY_FILE = os.path.join(os.path.dirname(__file__),
                "..", "keys", "id_rsa")
@@ -396,6 +397,61 @@ class BaseVM(object):
     def qmp(self, *args, **kwargs):
         return self._guest.qmp(*args, **kwargs)
 
+
+def parse_config(config, args):
+    """ Parse yaml config and populate our config structure.
+        The yaml config allows the user to override the
+        defaults for VM parameters.  In many cases these
+        defaults can be overridden without rebuilding the VM."""
+    if args.config:
+        config_file = args.config
+    elif 'QEMU_CONFIG' in os.environ:
+        config_file = os.environ['QEMU_CONFIG']
+    else:
+        return config
+    if not os.path.exists(config_file):
+        raise Exception("config file {} does not exist".format(config_file))
+    with open(config_file) as f:
+        yaml_dict = yaml.safe_load(f)
+    if 'target-conf' in yaml_dict:
+        target_dict = yaml_dict['target-conf']
+        if 'username' in target_dict and target_dict['username'] != 'root':
+            config['guest_user'] = target_dict['username']
+        if 'password' in target_dict:
+            config['root_pass'] = target_dict['password']
+            config['guest_pass'] = target_dict['password']
+        if any (k in target_dict for k in ("ssh_key","ssh_pub_key")) and \
+           not all (k in target_dict for k in ("ssh_key","ssh_pub_key")):
+            missing_key = "ssh_pub_key" \
+              if 'ssh_key' in target_dict else "ssh_key"
+            raise Exception("both ssh_key and ssh_pub_key required. "
+                            "{} key is missing.".format(missing_key))
+        if 'ssh_key' in target_dict:
+            config['ssh_key_file'] = target_dict['ssh_key']
+            if not os.path.exists(config['ssh_key_file']):
+                raise Exception("ssh key file not found.")
+        if 'ssh_pub_key' in target_dict:
+            config['ssh_pub_key_file'] = target_dict['ssh_pub_key']
+            if not os.path.exists(config['ssh_pub_key_file']):
+                raise Exception("ssh pub key file not found.")
+        if 'machine' in target_dict:
+            config['machine'] = target_dict['machine']
+        if 'qemu_args' in target_dict:
+            qemu_args = target_dict['qemu_args']
+            qemu_args = qemu_args.replace('\n', ' ').replace('\r', '')
+            config['extra_args'] = qemu_args.split(' ')
+        if 'memory' in target_dict:
+            config['memory'] = target_dict['memory']
+        if 'dns' in target_dict:
+            config['dns'] = target_dict['dns']
+        if 'cpu' in target_dict:
+            config['cpu'] = target_dict['cpu']
+        if 'ssh_port' in target_dict:
+            config['ssh_port'] = target_dict['ssh_port']
+        if 'install_cmds' in target_dict:
+            config['install_cmds'] = target_dict['install_cmds']
+    return config
+
 def parse_args(vmcls):
 
     def get_default_jobs():
@@ -430,6 +486,9 @@ def parse_args(vmcls):
                       help="Interactively run command")
     parser.add_option("--snapshot", "-s", action="store_true",
                       help="run tests with a snapshot")
+    parser.add_option("--config", "-c", default=None,
+                      help="Provide config yaml for configuration. "\
+                           "See config_example.yaml for example.")
     parser.disable_interspersed_args()
     return parser.parse_args()
 
@@ -441,6 +500,7 @@ def main(vmcls, config=None):
         if not argv and not args.build_qemu and not args.build_image:
             print("Nothing to do?")
             return 1
+        config = parse_config(config, args)
         logging.basicConfig(level=(logging.DEBUG if args.debug
                                    else logging.WARN))
         vm = vmcls(debug=args.debug, vcpus=args.jobs, config=config)
diff --git a/tests/vm/config_example.yml b/tests/vm/config_example.yml
new file mode 100644
index 0000000000..0a1fec3824
--- /dev/null
+++ b/tests/vm/config_example.yml
@@ -0,0 +1,52 @@
+#
+# Example yaml for use by any of the scripts in tests/vm.
+# Can be provided as an environment variable QEMU_CONFIG
+#
+target-conf:
+
+    # If any of the below are not provided, we will just use the qemu defaults.
+
+    # Login username (has to be sudo enabled)
+    #username: qemu
+
+    # Password is used by root and default login user.
+    #password: "qemupass"
+
+    # If one key is provided, both must be provided.
+    #ssh_key: /complete/path/of/your/keyfile/id_rsa
+    #ssh_pub_key: /complete/path/of/your/keyfile/id_rsa.pub
+
+    cpu: max
+    machine: virt,gic_version=3
+    memory: 16G
+
+    # The below is an example for how to configure NUMA topology with
+    # 4 NUMA nodes and 2 different NUMA distances.
+    qemu_args: "-smp cpus=16,sockets=2,cores=8
+                -object memory-backend-ram,size=4G,policy=bind,host-nodes=0,id=ram-node0
+                -object memory-backend-ram,size=4G,policy=bind,host-nodes=0,id=ram-node1
+                -object memory-backend-ram,size=4G,policy=bind,host-nodes=1,id=ram-node2
+                -object memory-backend-ram,size=4G,policy=bind,host-nodes=1,id=ram-node3
+                -numa node,memdev=ram-node0,cpus=0-3,nodeid=0 -numa node,memdev=ram-node1,cpus=4-7,nodeid=1
+                -numa node,memdev=ram-node2,cpus=8-11,nodeid=2 -numa node,memdev=ram-node3,cpus=12-15,nodeid=3
+                -numa dist,src=0,dst=1,val=15 -numa dist,src=2,dst=3,val=15
+                -numa dist,src=0,dst=2,val=20 -numa dist,src=0,dst=3,val=20
+                -numa dist,src=1,dst=2,val=20 -numa dist,src=1,dst=3,val=20"
+
+    # By default we do not set the DNS.
+    # You override the defaults by setting the below.
+    #dns: 1.234.567.89
+
+    # By default we will use a "block" device, but
+    # you can also boot from a "scsi" device.
+    # Just keep in mind your scripts might need to change
+    # As you will have /dev/sda instead of /dev/vda (for block device)
+    #boot_dev_type: "scsi"
+
+    # By default the ssh port is not fixed.
+    # A fixed ssh port makes it easier for automated tests.
+    #ssh_port: 5555
+
+    # To install a different set of packages, provide a command to issue
+    #install_cmds: "apt-get update ; apt-get build-dep -y qemu"
+
