test: add functional tests for booting secret free VMs

Add a test that we can boot VMs and initrds with secret freedom
enabled.

Signed-off-by: Patrick Roy <roypat@amazon.co.uk>

Author: roypat

tests/integration_tests/functional/test_secret_freedom.py

@@ -0,0 +1,75 @@
+# Copyright 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""Test secret-freedom related functionality."""
+
+import pytest
+
+from framework import defs
+from framework.microvm import Serial
+from framework.properties import global_props
+from integration_tests.performance.test_initrd import INITRD_FILESYSTEM
+
+pytestmark = [
+    pytest.mark.skipif(
+        global_props.host_linux_version_metrics != "next",
+        reason="Secret Freedom is only supported on the in-dev upstream kernels for now",
+    ),
+    pytest.mark.skipif(
+        global_props.instance == "m6g.metal",
+        reason="Secret Freedom currently only works on ARM hardware conforming to at least ARMv8.4 as absense of ARM64_HAS_STAGE2_FWB causes kernel panics because of dcache flushing during stage2 page table entry installation",
+    ),
+]
+
+
+def test_secret_free_boot(microvm_factory, guest_kernel, rootfs):
+    """Tests that a VM can boot, e.g. some basic I/O works through userspace bounce buffers"""
+    vm = microvm_factory.build(guest_kernel, rootfs)
+    vm.spawn()
+    vm.memory_monitor = None
+    vm.basic_config(secret_free=True)
+    vm.add_net_iface()
+    vm.start()
+
+
+def test_secret_free_initrd(microvm_factory, guest_kernel):
+    """
+    Test that we can boot a secret hidden initrd (e.g. a VM with no I/O devices)
+    """
+    fs = defs.ARTIFACT_DIR / "initramfs.cpio"
+    uvm = microvm_factory.build(guest_kernel)
+    uvm.initrd_file = fs
+    uvm.help.enable_console()
+    uvm.spawn()
+    uvm.memory_monitor = None
+
+    uvm.basic_config(
+        add_root_device=False,
+        vcpu_count=1,
+        boot_args="console=ttyS0 reboot=k panic=1 pci=off",
+        use_initrd=True,
+        secret_free=True,
+    )
+
+    uvm.start()
+    serial = Serial(uvm)
+    serial.open()
+    serial.rx(token="# ")
+    serial.tx("mount |grep rootfs")
+    serial.rx(token=f"rootfs on / type {INITRD_FILESYSTEM}")
+
+
+def test_secret_free_snapshot_creation(microvm_factory, guest_kernel, rootfs):
+    """Test that snapshot creation works for secret hidden VMs"""
+    vm = microvm_factory.build(guest_kernel, rootfs)
+    vm.spawn()
+    vm.memory_monitor = None
+    vm.basic_config(secret_free=True)
+    vm.add_net_iface()
+    vm.start()
+
+    snapshot = vm.snapshot_full()
+
+    # After restoration, the VM will not be secret hidden anymore, as that's not supported yet.
+    # But we can at least test that in principle, the snapshot creation worked.
+    vm = microvm_factory.build_from_snapshot(snapshot)
+    vm.ssh.check_output("true")