Re: [PATCH v2] tests/functional: Add PCI hotplug test for aarch64

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, May 12, 2025 at 01:36:33PM +0100, Gustavo Romero wrote:
> Add a functional test, aarch64_hotplug_pci, to exercise PCI hotplug and
> hot-unplug on arm64. Currently, the aarch64 'virt' machine uses the PCIe
> native controller and does not support ACPI-based hotplugging. However,
> since support is planned, this test sets 'acpi=force' and specifies an
> EDK2 firmware image in advance. This is harmless and prepares for future
> ACPI support.

Based on what's written here, it sounds like 'acpi=force' will result
in this test case changing from exercising PCI hotplug, to exercising
ACPI hotplug at some arbitrary point in the future. This isn't what
I'd call a harmless future change.

If the 'virt' machine ever switches from PCI to ACPI hotplug, this
will have to be tied to a machine type version. As such QEMU will
need to support /both/ PCI and ACPI hotplug for a long period of
time, and by implication we would need to be testing both.

I'd think this test should be written to exclusively test the current
PCI hotplug, and at a future date when ACPI hotplug is introduced,
then a 2nd test method can be addded, albeit with a lot of common
code shared.

> 
> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
> ---
>  MAINTAINERS                                  |  5 ++
>  tests/functional/meson.build                 |  1 +
>  tests/functional/test_aarch64_hotplug_pci.py | 73 ++++++++++++++++++++
>  3 files changed, 79 insertions(+)
>  create mode 100755 tests/functional/test_aarch64_hotplug_pci.py
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 23174b4ca7..9ebb768214 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2065,6 +2065,11 @@ S: Supported
>  F: include/hw/pci/pcie_doe.h
>  F: hw/pci/pcie_doe.c
>  
> +ARM PCI Hotplug
> +M: Gustavo Romero <gustavo.romero@linaro.org>
> +S: Supported
> +F: tests/functional/test_aarch64_hotplug_pci.py
> +
>  ACPI/SMBIOS
>  M: Michael S. Tsirkin <mst@redhat.com>
>  M: Igor Mammedov <imammedo@redhat.com>
> diff --git a/tests/functional/meson.build b/tests/functional/meson.build
> index 52b4706cfe..2d68840fa2 100644
> --- a/tests/functional/meson.build
> +++ b/tests/functional/meson.build
> @@ -83,6 +83,7 @@ tests_aarch64_system_quick = [
>  tests_aarch64_system_thorough = [
>    'aarch64_aspeed_ast2700',
>    'aarch64_aspeed_ast2700fc',
> +  'aarch64_hotplug_pci',
>    'aarch64_imx8mp_evk',
>    'aarch64_raspi3',
>    'aarch64_raspi4',
> diff --git a/tests/functional/test_aarch64_hotplug_pci.py b/tests/functional/test_aarch64_hotplug_pci.py
> new file mode 100755
> index 0000000000..05c92d7a45
> --- /dev/null
> +++ b/tests/functional/test_aarch64_hotplug_pci.py
> @@ -0,0 +1,73 @@
> +#!/usr/bin/env python3
> +#
> +# The test hotplugs a PCI device and checks it on a Linux guest.
> +#
> +# Copyright (c) 2025 Linaro Ltd.
> +#
> +# Author:
> +#  Gustavo Romero <gustavo.romero@linaro.org>
> +#
> +# This work is licensed under the terms of the GNU GPL, version 2 or
> +# later.  See the COPYING file in the top-level directory.
> +
> +from os import path
> +from qemu_test import LinuxKernelTest, Asset, exec_command_and_wait_for_pattern
> +from qemu_test import BUILD_DIR
> +
> +class HotplugPCI(LinuxKernelTest):
> +
> +    ASSET_KERNEL = Asset(
> +        ('https://ftp.debian.org/debian/dists/stable/main/installer-arm64/'
> +         'current/images/netboot/debian-installer/arm64/linux'),
> +        '3821d4db56d42c6a4eac62f31846e35465940afd87746b4cfcdf5c9eca3117b2')
> +
> +    ASSET_INITRD = Asset(
> +        ('https://ftp.debian.org/debian/dists/stable/main/installer-arm64/'
> +         'current/images/netboot/debian-installer/arm64/initrd.gz'),
> +        '2583ec22b45265ad69e82f198674f53d4cd85be124fe012eedc2fd91156bc4b4')
> +
> +    def test_hotplug_pci(self):
> +
> +        self.set_machine('virt')
> +        self.vm.add_args('-m', '512M')
> +        self.vm.add_args('-cpu', 'cortex-a57')
> +        self.vm.add_args('-append',
> +                         'console=ttyAMA0,115200 acpi=force init=/bin/sh')
> +        self.vm.add_args('-device',
> +                         'pcie-root-port,bus=pcie.0,chassis=1,slot=1,id=pcie.1')
> +        self.vm.add_args('-bios', path.join(BUILD_DIR, 'pc-bios',
> +                         'edk2-aarch64-code.fd'))
> +
> +        # BusyBox prompt
> +        prompt = "~ #"
> +        self.launch_kernel(self.ASSET_KERNEL.fetch(),
> +                           self.ASSET_INITRD.fetch(),
> +                           wait_for=prompt)
> +
> +        # Check for initial state: 2 network adapters, lo and enp0s1.
> +        exec_command_and_wait_for_pattern(self,
> +                                          'ls -l /sys/class/net | wc -l',
> +                                          '2')
> +
> +        # Hotplug one network adapter to the root port, i.e. pcie.1 bus.
> +        self.vm.cmd('device_add',
> +                    driver='virtio-net-pci',
> +                    bus='pcie.1',
> +                    addr=0,
> +                    id='na')
> +        # Wait for the kernel to recognize the new device.
> +        self.wait_for_console_pattern('virtio-pci')
> +        self.wait_for_console_pattern('virtio_net')
> +
> +        # Check if there is a new network adapter.
> +        exec_command_and_wait_for_pattern(self,
> +                                          'ls -l /sys/class/net | wc -l',
> +                                          '3')
> +
> +        self.vm.cmd('device_del', id='na')
> +        exec_command_and_wait_for_pattern(self,
> +                                          'ls -l /sys/class/net | wc -l',
> +                                          '2')
> +
> +if __name__ == '__main__':
> +    LinuxKernelTest.main()
> -- 
> 2.43.0
> 
> 

With regards,
Daniel
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