tests: Adjust path for swtpm state to use path under /var/tmp/

To avoid AppArmor-related test failures when functional test are run from
somewhere under /mnt, adjust the path to swtpm's state to use an AppArmor-
supported path, such as /var/tmp, which is provided by the python function
tempfile.TemporaryDirectory().

An update to swtpm's AppArmor profile is also being done to support /var/tmp.

Link: https://lore.kernel.org/qemu-devel/CAFEAcA8A=kWLtTZ+nua-MpzqkaEjW5srOYZruZnE2tB6vmoMig@mail.gmail.com/
Link: https://github.com/stefanberger/swtpm/pull/944
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Fixes: f04cb2d00d ("tests/functional: Convert most Aspeed machine tests")
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

tests/functional/test_arm_aspeed.py

@@ -227,11 +227,14 @@ class AST2x00Machine(LinuxKernelTest):
 
         image_path = self.ASSET_BR2_202302_AST2600_TPM_FLASH.fetch()
 
-        socket_dir = tempfile.TemporaryDirectory(prefix="qemu_")
-        socket = os.path.join(socket_dir.name, 'swtpm-socket')
+        tpmstate_dir = tempfile.TemporaryDirectory(prefix="qemu_")
+        socket = os.path.join(tpmstate_dir.name, 'swtpm-socket')
 
+        # We must put the TPM state dir in /tmp/, not the build dir,
+        # because some distros use AppArmor to lock down swtpm and
+        # restrict the set of locations it can access files in.
         subprocess.run(['swtpm', 'socket', '-d', '--tpm2',
-                        '--tpmstate', f'dir={self.vm.temp_dir}',
+                        '--tpmstate', f'dir={tpmstate_dir.name}',
                         '--ctrl', f'type=unixio,path={socket}'])
 
         self.vm.add_args('-chardev', f'socket,id=chrtpm,path={socket}')