ci: add qemu test mechanism

Add a mechanism to test behaviours don't relate to hardware. These can
be effectively tested without need of the target platform using qemu.

This uses Python and pytest. Specific tests to follow.

For now, this is just the raw test that will need to be run manually,
and depends on the developer already having built a disk-ufs.img by
hand using the instructions in README.md. Automation and integration
into GitHub Actions will follow. How-to documentation would be useful
but would be superseded by that automation and integration, so this is
omitted for now.

Signed-off-by: Robie Basak <[email protected]>

Author: basak-qcom

ci/qemu_test.py

@@ -0,0 +1,62 @@
+"""Tests that are entirely qemu based, so do not require test hardware"""
+
+# Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+# SPDX-License-Identifier: BSD-3-Clause
+
+import os
+import signal
+import subprocess
+import tempfile
+
+import pexpect
+import pytest
+
+
+@pytest.fixture
+def vm():
+    """A pexpect.spawn object attached to the serial console of a VM freshly
+    booting with a CoW base of disk-ufs.img"""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        qcow_path = os.path.join(tmpdir, "disk1.qcow")
+        subprocess.run(
+            [
+                "qemu-img",
+                "create",
+                "-b",
+                os.path.join(os.getcwd(), "disk-ufs.img"),
+                "-f",
+                "qcow",
+                "-F",
+                "raw",
+                qcow_path,
+            ],
+            check=True,
+        )
+        child = pexpect.spawn(
+            "qemu-system-aarch64",
+            [
+                "-cpu",
+                "cortex-a57",
+                "-m",
+                "2048",
+                "-M",
+                "virt",
+                "-drive",
+                f"if=none,file={qcow_path},format=qcow,id=disk1",
+                "-device",
+                "virtio-scsi-pci,id=scsi1",
+                "-device",
+                "scsi-hd,bus=scsi1.0,drive=disk1,physical_block_size=4096,logical_block_size=4096",
+                "-nographic",
+                "-bios",
+                "/usr/share/AAVMF/AAVMF_CODE.fd",
+            ],
+        )
+        yield child
+
+        # No need to be nice; that would take time
+        child.kill(signal.SIGKILL)
+
+        # If this blocks then we have a problem. Better to hang than build up
+        # excess qemu processes that won't die.
+        child.wait()