[PATCH 4/4] test: py: efiloader: test EFI ResetSystem from booted Linux

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

From: Ahmad Fatoum <a.fatoum@barebox.org>

arm64 machine_restart() calls efi_reboot() before falling back to
PSCI whenever EFI runtime services are available, so rebooting the
booted Debian kernel calls barebox's ResetSystem implementation,
which lives entirely in the .efi_runtime code section.

This way, we have a test that verifies we can call into efi_runtime
section both at boot and at runtime.

QEMU would restart the VM on a successful reset, so the test expects the
barebox banner to reappear on the console.

Assisted-by: Claude:fable-5
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 test/py/test_linux_efiloader.py | 57 +++++++++++++++++++++++++++++----
 1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/test/py/test_linux_efiloader.py b/test/py/test_linux_efiloader.py
index a76e55a91e52..eae6703e9d49 100644
--- a/test/py/test_linux_efiloader.py
+++ b/test/py/test_linux_efiloader.py
@@ -26,13 +26,7 @@ def get_dmesg(shell, grep=None):
     return stdout
 
 
-@pytest.mark.lg_feature(['bootable', 'efi', 'testfs'])
-@pytest.mark.parametrize('efiloader', [False, True])
-def test_boot_manual_with_initrd(strategy, barebox, env, efiloader, debian_iso):
-    """Test booting Debian kernel directly without GRUB"""
-
-    barebox.run_check(f"global.bootm.efi={'required' if efiloader else 'disabled'}")
-
+def configure_bootm(strategy, barebox):
     def get_option(strategy, opt):
         config = strategy.target.env.config
         return config.get_target_option(strategy.target.name, opt)
@@ -57,6 +51,16 @@ def test_boot_manual_with_initrd(strategy, barebox, env, efiloader, debian_iso):
     # Speed up subsequent runs a bit
     barebox.run_check("global linux.bootargs.noapparmor=apparmor=0")
 
+
+@pytest.mark.lg_feature(['bootable', 'efi', 'testfs'])
+@pytest.mark.parametrize('efiloader', [False, True])
+def test_boot_manual_with_initrd(strategy, barebox, env, efiloader, debian_iso):
+    """Test booting Debian kernel directly without GRUB"""
+
+    barebox.run_check(f"global.bootm.efi={'required' if efiloader else 'disabled'}")
+
+    configure_bootm(strategy, barebox)
+
     # Boot the kernel - it should use EFI stub by default
     with strategy.boot_kernel(bootm=True) as shell:
         shell.run_check("grep -q apparmor=0 /proc/cmdline")
@@ -127,3 +131,42 @@ def check_efivars_filesystem_not_empty(shell):
     assert ret == 0
 
     assert len(stdout), "EFI variables directory is empty"
+
+
+@pytest.mark.lg_feature(['bootable', 'efi', 'testfs'])
+def test_efi_reset_system(strategy, barebox, env, debian_iso):
+    """Test rebooting Linux via barebox's EFI ResetSystem runtime service
+
+    arm64 machine_restart() calls efi_reboot() before falling back to
+    PSCI whenever EFI runtime services are available, so a reboot from
+    the booted kernel calls into the barebox .efi_runtime code section
+    after ExitBootServices.
+    """
+
+    barebox.run_check("global.bootm.efi=required")
+
+    configure_bootm(strategy, barebox)
+
+    with strategy.boot_kernel(bootm=True) as shell:
+        # ensure the kernel did not give up on EFI runtime services
+        check_expected_efi_messages(shell, env)
+        stdout, _, _ = shell.run("dmesg | grep 'Runtime Services are disabled'")
+        assert stdout == [], "kernel disabled EFI runtime services"
+
+        strategy.console.sendline("reboot -f")
+
+        # QEMU reboots the VM on a successful reset, so barebox comes
+        # back up on the same console
+        _, before, _, _ = strategy.console.expect(
+            [r"barebox 2\d{3}"], timeout=120)
+
+        # A faulting ResetSystem would be caught by the kernel, which
+        # then complains and falls back to PSCI. That also reboots, so
+        # check the console log to tell the two apart.
+        before = before.decode("utf-8", errors="replace")
+        for pattern in ["Synchronous exception in EFI runtime service",
+                        "Unable to handle kernel",
+                        "Internal error",
+                        "Runtime Services are disabled"]:
+            assert pattern not in before, \
+                   f"kernel reported EFI runtime fault: {pattern}"
-- 
2.47.3