env_process: improve the nested virtualization support

This patch adds the support to run nested VMs in threads and pass
on the params from one level to next level which means currently
the tests in each level would run with the default params of the
test but with this support user can pass the customised params
specific to levels or specific to VMs in the levels while starting
the tests.

Signed-off-by: Balamuruhan S <bala24@linux.vnet.ibm.com>

virttest/env_process.py

@@ -8,6 +8,7 @@
 import shutil
 import sys
 import copy
+import ast
 import multiprocessing
 try:
     from urllib.request import ProxyHandler, build_opener, install_opener
@@ -66,6 +67,8 @@
 #: information from the output produced by `qemu -version`
 QEMU_VERSION_RE = r"QEMU (?:PC )?emulator version\s([0-9]+\.[0-9]+\.[0-9]+)\s?\((.*?)\)"
 
+THREAD_ERROR = False
+
 
 def preprocess_image(test, params, image_name, vm_process_status=None):
     """
@@ -1096,21 +1099,40 @@ def preprocess(test, params, env):
 
     # start test in nested guest
     if params.get("run_nested_guest_test", "no") == "yes":
+        def thread_func(obj):
+            """
+            Thread method to trigger nested VM test
+
+            :param obj: AvocadoGuest Object of the VM
+            """
+            global THREAD_ERROR
+            try:
+                obj.run_avocado()
+            except Exception as info:
+                logging.error(info)
+                THREAD_ERROR = True
         nest_params = params.copy()
         current_level = nest_params.get("nested_guest_level", "L1")
         max_level = nest_params.get("nested_guest_max_level", "L1")
-        nest_timeout = int(nest_params.get("nested_guest_timeout", "3600"))
-        install_type = nest_params.get("avocado_guest_install_type", "git")
-        nest_vms = env.get_all_vms()
-        # Have buffer memory 1G for VMs to work seamlessly
-        nest_memory = (int(nest_params.get("mem")) // len(nest_vms)) - 1024
-        if nest_memory < 512:
-            raise exceptions.TestCancel("Memory is not sufficient for "
-                                        "VMs to boot and perform nested "
-                                        "virtualization tests")
-        # set memory for the nested VM
-        nest_params["vt_extra_params"] = "mem=\"%s\"" % nest_memory
         if current_level != max_level:
+            threads = []
+            nest_timeout = int(nest_params.get("nested_guest_timeout", "3600"))
+            install_type = nest_params.get("avocado_guest_install_type", "git")
+            nest_vms = env.get_all_vms()
+            # Have buffer memory 1G for VMs to work seamlessly
+            nest_memory = (int(nest_params.get("mem")) // len(nest_vms)) - 1024
+            if nest_memory < 512:
+                raise exceptions.TestCancel("Memory is not sufficient for "
+                                            "VMs to boot and perform nested "
+                                            "virtualization tests")
+            # set memory for the nested VM
+            nest_params["vt_extra_params"] = "mem=\"%s\"" % nest_memory
+            # pass the params current level to next level
+            nested_params = nest_params.get("nested_params", {})
+            nest_params["vt_extra_params"] += " nested_params=\"%s\"" % nested_params
+            # update the current level's param with nested params sent
+            # from previous level
+            nest_params.update(ast.literal_eval(nested_params))
             next_level = "L%s" % (int(current_level[-1]) + 1)
             logging.debug("Test is running in Guest level: %s", current_level)
             for vm in nest_vms:
@@ -1130,9 +1152,15 @@ def preprocess(test, params, env):
                                               avocado_vt=True,
                                               reinstall=False,
                                               add_args=avocadotestargs)
-                if not obj.run_avocado():
-                    raise exceptions.TestFail("Test inside nested guest "
-                                              "reported failure")
+                thread = threading.Thread(target=thread_func, args=(obj,))
+                threads.append(thread)
+            for thread in threads:
+                thread.start()
+            for thread in threads:
+                thread.join()
+            if THREAD_ERROR:
+                raise exceptions.TestFail("Test inside nested guest "
+                                          "reported failure")
     return params