CPI: Add test case to check hypervisor bit of cpi info

libvirt/tests/cfg/guest_kernel_debugging/cpi_info.cfg

@@ -16,4 +16,7 @@
         - long_system_name:
             test_case_name = long_system_name
             test_system_name = "VERYLONGSYSTEMNAME123456789"
+        - nested_kvm_cpi:
+            test_case_name = nested_kvm_cpi
+            kvm_module_parameters = 'nested=1'
 

libvirt/tests/src/guest_kernel_debugging/cpi_info.py

@@ -1,7 +1,9 @@
 import logging as log
 import re
+import time
 
 from virttest import utils_misc, virsh
+from virttest import utils_package
 from virttest.utils_cpi import (
     CPIChecker,
     get_cpi_config,
@@ -298,6 +300,100 @@ def test_long_system_name(long_system_name):
 
         logging.info("Long system name validation test passed")
 
+    def test_nested_kvm_cpi():
+        """
+        Test case 4: Test CPI system_level behavior in nested KVM environment
+
+        Steps:
+        1. L2 guest: Check /sys/firmware/cpi/system_level and verify hypervisor_bit is '0'
+        2. L2 guest: enable nested and Boot L3 guest
+        3. L2 guest: Check /sys/firmware/cpi/system_level and verify hypervisor_bit is '1'
+        """
+        logging.info("=== Test Case 4: Nested KVM CPI ===")
+
+        def check_and_enable_nested(session):
+            current_nested = None
+            try:
+                # Check on L2 guest
+                current_nested = (session.cmd_output(
+                    "cat /sys/module/kvm/parameters/nested",
+                    timeout=30).strip())
+                logging.info(f"Current nested status: {current_nested}")
+            except Exception as e:
+                logging.warning(
+                    f"Failed to check current nested status: {e}")
+
+            # Reload kvm module with nested=1 if not already enabled
+            if current_nested != "1":
+                logging.info("Reloading kvm module with nested=1")
+                try:
+                    # Reload kvm modules with nested enabled on L2 guest
+                    session.cmd_output(
+                        "modprobe -r kvm ; modprobe kvm nested=1",
+                        timeout=30)
+                    # Verify nested is enabled
+                    new_status = session.cmd_output(
+                        "cat /sys/module/kvm/parameters/nested",
+                        timeout=30).strip()
+                    if new_status != "1":
+                        test.fail("Failed to enable nested virtualization")
+                    logging.info(
+                        "Nested virtualization enabled successfully")
+                except Exception as e:
+                    test.fail(f"Failed to reload kvm module: {e}")
+            else:
+                logging.info("Nested virtualization already enabled")
+
+        logging.info("Step 1: Checking CPI system_level on L2 guest")
+        session = None
+        try:
+            # Login L2 guest
+            session = vm.wait_for_login(timeout=60)
+
+            checker = CPIChecker(vm, serial=serial)
+            system_level = checker.get_cpi_field("system_level")
+            parsed = checker._parse_system_level(system_level)
+            if parsed['hypervisor_bit'] != 0:
+                test.fail(f"L2 hypervisor_bit should be 0, but actual is "
+                          f"{parsed['hypervisor_bit']}")
+
+            logging.info("Step 2: Enable nested on L2 guest and Boot L3 guest")
+            check_and_enable_nested(session)
+
+            # install qemu-kvm on L2
+            logging.info("Installing qemu-kvm")
+            utils_package.package_install("qemu-kvm", session=session)
+
+            logging.info("Starting L3 guest")
+            start_cmd = \
+                "/usr/libexec/qemu-kvm -machine s390-ccw-virtio -no-shutdown &"
+            try:
+                session.sendline(start_cmd)
+            except Exception as e:
+                logging.error(f"Failed to start L3 guest: {e}")
+                test.fail(f"Failed to start L3 guest: {e}")
+
+            # wait L3 guest to boot up
+            logging.info("waiting for L3 guest to boot")
+            time.sleep(5)
+            # Verify qemu-kvm process is running
+            qemu_status = session.cmd_status("pgrep -f qemu-kvm")
+            if qemu_status != 0:
+                test.fail("L3 guest (qemu-kvm) process not found")
+
+            logging.info("Step 3: Checking CPI system_level on L2 guest")
+            system_level = checker.get_cpi_field("system_level")
+            parsed = checker._parse_system_level(system_level)
+            if parsed['hypervisor_bit'] != 1:
+                test.fail(f"L2 hypervisor_bit should be 1, but actual is "
+                          f"{parsed['hypervisor_bit']}")
+        finally:
+            if session is not None:
+                try:
+                    session.close()
+                except Exception as e:
+                    logging.warning(f"Failed to close session: {e}")
+
     def cleanup_cpi_config():
         """
         Clean up CPI configuration by restoring from backup
@@ -315,6 +411,8 @@ def cleanup_cpi_config():
             test_managedsave()
         elif test_case_name == "long_system_name":
             test_long_system_name(test_system_name)
+        elif test_case_name == "nested_kvm_cpi":
+            test_nested_kvm_cpi()
         else:
             test.error(f"Unknown test case: {test_case_name}")