From: Ani Sinha <anisinha@redhat.com>
A new functional test is added that exercises the code changes related to
closing of the old KVM VM file descriptor and opening a new one upon VM reset.
This normally happens when confidential guests are reset but for
non-confidential guests, we use a special machine specific debug/test parameter
'x-change-vmfd-on-reset' to enable this behavior.
Only specific code changes related to re-initialisation of SEV-ES, SEV-SNP and
TDX platforms are not exercised in this test as they require hardware that
supports running confidential guests.
Signed-off-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/20260225035000.385950-34-anisinha@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
MAINTAINERS | 1 +
tests/functional/x86_64/meson.build | 1 +
tests/functional/x86_64/test_rebuild_vmfd.py | 136 +++++++++++++++++++
3 files changed, 138 insertions(+)
create mode 100755 tests/functional/x86_64/test_rebuild_vmfd.py
diff --git a/MAINTAINERS b/MAINTAINERS
index a8e1546de1e..83c05112a33 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -157,6 +157,7 @@ M: Ani Sinha <anisinha@redhat.com>
M: Paolo Bonzini <pbonzini@redhat.com>
S: Maintained
F: stubs/kvm.c
+F: tests/functional/x86_64/test_rebuild_vmfd.py
Guest CPU cores (TCG)
---------------------
diff --git a/tests/functional/x86_64/meson.build b/tests/functional/x86_64/meson.build
index beab4f304ba..05e4914c772 100644
--- a/tests/functional/x86_64/meson.build
+++ b/tests/functional/x86_64/meson.build
@@ -37,4 +37,5 @@ tests_x86_64_system_thorough = [
'vhost_user_bridge',
'virtio_balloon',
'virtio_gpu',
+ 'rebuild_vmfd',
]
diff --git a/tests/functional/x86_64/test_rebuild_vmfd.py b/tests/functional/x86_64/test_rebuild_vmfd.py
new file mode 100755
index 00000000000..5a8e5fd89b4
--- /dev/null
+++ b/tests/functional/x86_64/test_rebuild_vmfd.py
@@ -0,0 +1,136 @@
+#!/usr/bin/env python3
+#
+# Functional tests exercising guest KVM file descriptor change on reset.
+#
+# Copyright © 2026 Red Hat, Inc.
+#
+# Author:
+# Ani Sinha <anisinha@redhat.com>
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import os
+from qemu.machine import machine
+
+from qemu_test import QemuSystemTest, Asset, exec_command_and_wait_for_pattern
+from qemu_test import wait_for_console_pattern
+
+class KVMGuest(QemuSystemTest):
+
+ # ASSET UKI was generated using
+ # https://gitlab.com/kraxel/edk2-tests/-/blob/unittest/tools/make-supermin.sh
+ ASSET_UKI = Asset('https://gitlab.com/anisinha/misc-artifacts/'
+ '-/raw/main/uki.x86-64.efi?ref_type=heads',
+ 'e0f806bd1fa24111312e1fe849d2ee69808d4343930a5'
+ 'dc8c1688da17c65f576')
+ # ASSET_OVMF comes from /usr/share/edk2/ovmf/OVMF.stateless.fd of a
+ # fedora core 43 distribution which in turn comes from the
+ # edk2-ovmf-20251119-3.fc43.noarch rpm of that distribution.
+ ASSET_OVMF = Asset('https://gitlab.com/anisinha/misc-artifacts/'
+ '-/raw/main/OVMF.stateless.fd?ref_type=heads',
+ '58a4275aafa8774bd6b1540adceae4ea434b8db75b476'
+ '11839ff47be88cfcf22')
+
+ def common_vm_setup(self, kvm_args=None, cpu_args=None):
+ self.set_machine('q35')
+ self.require_accelerator("kvm")
+
+ self.vm.set_console()
+ if kvm_args:
+ self.vm.add_args("-accel", "kvm,%s" %kvm_args)
+ else:
+ self.vm.add_args("-accel", "kvm")
+ self.vm.add_args("-smp", "2")
+ if cpu_args:
+ self.vm.add_args("-cpu", "host,%s" %cpu_args)
+ else:
+ self.vm.add_args("-cpu", "host")
+ self.vm.add_args("-m", "2G")
+ self.vm.add_args("-nographic", "-nodefaults")
+
+
+ self.uki_path = self.ASSET_UKI.fetch()
+ self.ovmf_path = self.ASSET_OVMF.fetch()
+
+ self.vm.add_args('-kernel', self.uki_path)
+ self.vm.add_args("-bios", self.ovmf_path)
+ # enable KVM VMFD change on reset for a non-coco VM
+ self.vm.add_args("-machine", "q35,x-change-vmfd-on-reset=on")
+
+ # enable tracing of basic vmfd change function
+ self.vm.add_args("--trace", "kvm_reset_vmfd")
+
+ def launch_vm(self):
+ try:
+ self.vm.launch()
+ except machine.VMLaunchFailure as e:
+ if "Xen HVM guest support not present" in e.output:
+ self.skipTest("KVM Xen support is not present "
+ "(need v5.12+ kernel with CONFIG_KVM_XEN)")
+ elif "Property 'kvm-accel.xen-version' not found" in e.output:
+ self.skipTest("QEMU not built with CONFIG_XEN_EMU support")
+ else:
+ raise e
+
+ self.log.info('VM launched')
+ console_pattern = 'bash-5.1#'
+ wait_for_console_pattern(self, console_pattern)
+ self.log.info('VM ready with a bash prompt')
+
+ def vm_console_reset(self):
+ exec_command_and_wait_for_pattern(self, '/usr/sbin/reboot -f',
+ 'reboot: machine restart')
+ console_pattern = '# --- Hello world ---'
+ wait_for_console_pattern(self, console_pattern)
+ self.vm.shutdown()
+
+ def vm_qmp_reset(self):
+ self.vm.qmp('system_reset')
+ console_pattern = '# --- Hello world ---'
+ wait_for_console_pattern(self, console_pattern)
+ self.vm.shutdown()
+
+ def check_logs(self):
+ self.assertRegex(self.vm.get_log(),
+ r'kvm_reset_vmfd')
+ self.assertRegex(self.vm.get_log(),
+ r'virtual machine state has been rebuilt')
+
+ def test_reset_console(self):
+ self.common_vm_setup()
+ self.launch_vm()
+ self.vm_console_reset()
+ self.check_logs()
+
+ def test_reset_qmp(self):
+ self.common_vm_setup()
+ self.launch_vm()
+ self.vm_qmp_reset()
+ self.check_logs()
+
+ def test_reset_kvmpit(self):
+ self.common_vm_setup()
+ self.vm.add_args("--trace", "kvmpit_post_vmfd_change")
+ self.launch_vm()
+ self.vm_console_reset()
+ self.assertRegex(self.vm.get_log(),
+ r'kvmpit_post_vmfd_change')
+
+ def test_reset_xen_emulation(self):
+ self.common_vm_setup("xen-version=0x4000a,kernel-irqchip=split")
+ self.launch_vm()
+ self.vm_console_reset()
+ self.check_logs()
+
+ def test_reset_hyperv_vmbus(self):
+ self.common_vm_setup(None, "hv-syndbg,hv-relaxed,hv_time,hv-synic,"
+ "hv-vpindex,hv-runtime,hv-stimer")
+ self.vm.add_args("-device", "vmbus-bridge,irq=15")
+ self.vm.add_args("-trace", "vmbus_handle_vmfd_change")
+ self.launch_vm()
+ self.vm_console_reset()
+ self.assertRegex(self.vm.get_log(),
+ r'vmbus_handle_vmfd_change')
+
+if __name__ == '__main__':
+ QemuSystemTest.main()
--
2.53.0