Noble 24.04 minor improvements (#272)

* tests : qemu : output the qemu command to a script

this will allow users to run manually the guest after the test
this capability is useful for debugging purposes

* tests : qemu : shutdown the VM properly at qemu stop

right now, we use proc.terminate() to send SIGTERM to qemu process
this tends to corrupt the rootfs
this will prevent us from running the guest again with this rootfs
try to stop the VM (shutdown) properly first and terminate() it
later if necessary

tests/lib/Qemu.py

@@ -27,6 +27,7 @@
 import tempfile
 import time
 import sys
+import stat
 
 import util
 
@@ -73,6 +74,17 @@ def args(self):
             return ['-nographic']
         return []
 
+class QemuSerial():
+    def __init__(self, serial_file : str = None):
+        self.serial_file = serial_file
+    def args(self):
+        if self.serial_file:
+            return [
+                '-chardev', f'file,id=c1,path={self.serial_file},signal=off',
+                '-device', 'isa-serial,chardev=c1'
+            ]
+        return ['-serial', 'stdio']
+
 class QemuUserConfig:
     def __init__(self):
         self.nodefaults = True
@@ -229,6 +241,7 @@ def __init__(
                         'config': QemuUserConfig(),
                         'memory': QemuMemory(memory),
                         'ovmf' : QemuOvmf(machine),
+                        'serial' : QemuSerial(f'{self.workdir}/serial.log'),
                         'machine' : QemuMachineType(machine)}
         self.command = ['-pidfile', f'{self.workdir}/qemu.pid']
 
@@ -238,13 +251,6 @@ def get_command(self):
             _args.extend(p.args())
         return _args + self.command
 
-    def add_serial_to_file(self):
-        # serial to file
-        self.command = self.command + [
-            '-chardev', f'file,id=c1,path={self.workdir}/serial.log,signal=off',
-            '-device', 'isa-serial,chardev=c1'
-        ]
-
     def add_qemu_run_log(self):
         # serial to file
         self.command = self.command + [
@@ -346,6 +352,9 @@ def wait_for_state(self, s, retries=5):
     def wakeup(self):
         self.send_command("system_wakeup")
 
+    def powerdown(self):
+        self.send_command("system_powerdown")
+
     def __del__(self):
         if self.socket is not None:
             self.socket.close()
@@ -467,6 +476,15 @@ class QemuMachineService:
     QEMU_MACHINE_MONITOR = enum.auto()
     QEMU_MACHINE_QMP = enum.auto()
 
+# run script to run the guest
+# this is used for debugging purpose and allow users
+# to run the guest manually
+qemu_run_script = """
+#!/bin/bash
+echo "To connect to the VM : ssh -p {fwd_port} root@localhost"
+{cmd_str}
+"""
+
 class QemuMachine:
     debug_enabled = False
     # hold all qemu instances
@@ -498,7 +516,6 @@ def __init__(self,
             self.fwd_port = util.tcp_port_available()
             self.qcmd.add_port_forward(self.fwd_port)
         self.qcmd.add_qemu_run_log()
-        self.qcmd.add_serial_to_file()
 
         self.proc = None
         self.out = None
@@ -572,6 +589,8 @@ def run(self):
         """
         cmd = self.qcmd.get_command()
         print(' '.join(cmd))
+        script=f'{self.workdir_name}/run.sh'
+        self.write_cmd_to_file(script)
         self.proc = subprocess.Popen(cmd,
                                     stdout=subprocess.PIPE,
                                     stderr=subprocess.PIPE)
@@ -580,11 +599,7 @@ def run_and_wait(self):
         """
         Run qemu and wait for its start (by waiting for monitor file's availability)
         """
-        cmd = self.qcmd.get_command()
-        print(' '.join(cmd))
-        self.proc = subprocess.Popen(cmd,
-                                    stdout=subprocess.PIPE,
-                                    stderr=subprocess.PIPE)
+        self.run()
         QemuMonitor(self)
 
     def communicate(self):
@@ -602,13 +617,28 @@ def stop(self):
         """
         if self.proc is None:
             return
-        # self.proc.returncode== None -> not yet terminated
-        if self.proc.returncode is None:
-            try:
-                self.proc.terminate()
-                self.communicate()
-            except Exception as e:
-                print(f'Exception {e}')
+        if self.proc.returncode is not None:
+            return
+
+        # self.proc.returncode == None -> not yet terminated
+
+        # try to shutdown the VM properly, this is important to avoid
+        # rootfs corruption if we want to run the guest again
+        mon = QemuMonitor(self)
+        mon.powerdown()
+        try:
+            self.communicate()
+            return
+        except Exception as e:
+            pass
+
+        print('Qemu process did not shutdown properly, terminate it ...')
+        # terminate qemu process (SIGTERM)
+        try:
+            self.proc.terminate()
+            self.communicate()
+        except Exception as e:
+            print(f'Exception {e}')
 
     def reboot(self):
         """
@@ -623,6 +653,33 @@ def reboot(self):
         # run the VM again
         self.run()
 
+    def write_cmd_to_file(self, fname : str):
+        """
+        Write the qemu command to a executable bash script
+        """
+        # force -serial to stdio to be able to have the console on stdio
+        cur_serial = self.qcmd.plugins['serial']
+        self.qcmd.plugins['serial'] = QemuSerial()
+
+        cmd = self.qcmd.get_command()
+        with open(fname, 'w+') as run_script:
+            cmd_str=''
+            for el in cmd:
+                # escape qemu object with quotes
+                # for example : -object "{'qom-type': 'tdx-guest', 'id': 'tdx'}"
+                if el.startswith('{') and el.endswith('}'):
+                    cmd_str += f'\"{el}\" '
+                else:
+                    cmd_str += f'{el} '
+                script_contents = qemu_run_script.format(fwd_port=self.fwd_port,
+                                                         cmd_str=cmd_str)
+            run_script.write(script_contents)
+        f = pathlib.Path(fname)
+        f.chmod(f.stat().st_mode | stat.S_IEXEC)
+
+        # restore serial config
+        self.qcmd.plugins['serial'] = cur_serial
+
     def __del__(self):
         """
         Make sure we stop the qemu process if it is still running