Re: [PATCH 00/22] ACPI PCI Hotplug support on ARM

[Eric Auger <eric.auger@redhat.com>]

Hi Gustavo,

On 5/26/25 7:55 AM, Gustavo Romero wrote:
> Hi Eric,
>
> On 5/14/25 14:00, Eric Auger wrote:
>> This series enables ACPI PCI hotplug/hotunplug on ARM
>> and makes it default for 10.1 machine type. This aligns with
>> x86 q35 machine. Expected benefits should be similar to
>> those listed in [1].
>>
>> It is still possible to disable it using a virt machine
>> option: virt,acpi-pcihp=off and restore the legacy behavior.
>>
>> The infrastructure used in x86 is heavily reused and a
>> huge part of the series consists in moving code from
>> hw/i386/acpi-build.c to a generic place and slightly
>> adapting it to make it usable on ARM. The DSDT table is
>> augmented to support ACPI PCI hotplug elements.
>>
>> On ARM we use use a GED event to notify the OS about
>> hotplug events.
>>
>> I have not noticed any tests/qtest/bios-tables-test failures
>> neither on x86 nor ARM. x86 DSDT table has not changed.
>> ARM DSDT table definitively has but there are no tests
>> impacted. ARM misses hotplug tests that do exist on x86. This
>> most probably should be considered in the future.
>
> I've just posted a v1 for a acpi-pcihp=on test:
>
> https://mail.gnu.org/archive/html/qemu-devel/2025-05/msg05824.html
>
> The odd thing is that I noticed failures in the existing aarch64
> acpi tests in tests/qtest/bios-tables-test. At least the rename
> of the variable 'CTRL' to 'Local0' in the _OSC method should cause
> a mismatch against the current base DSDT? So I had to handle it
> via patches 1/5, 2/5, and 3/5. The diff is in the 3/5 commit body.

Thank you for contributing those tests.

Hum I think my mistake was to have executed the existing tests in KVM
acceleration mode only using
QTEST_QEMU_BINARY=qemu-system-aarch64 tests/qtest/bios-tables-test
direct execution.

The failing tests belong to the TCG category I think.

I will review your tests and if you allow me I may need to include
patches 1 and 3 in my series to prevent existing tests from failing, of
course with all your credits.

Thank you again for reporting the issue!

Eric




>
> Cheers,
> Gustavo
>
>> Best Regards
>>
>> Eric
>>
>> This series can be found at:
>> https://github.com/eauger/qemu/tree/arm-acpi-pcihp-v1
>>
>> previous RFC:
>> https://github.com/eauger/qemu/tree/arm-acpi-pcihp-rfc
>>
>> History:
>> RFC -> v1:
>> - First 3 trivial patches were pulled separately
>> - Fix of the register region size (0x18), ie. ACPI_PCIHP_SIZE
>> - addition of aml_pci_edsm which was not called in RFC
>> - acpi-index feature is now fixed. vms->bus was not set on
>>    acpi_pcihp_init. The init sequence is still hacky though. Suggestions
>>    appreciated.
>>
>> [1] [PATCH v6 0/6] Use ACPI PCI hot-plug for Q35
>> https://lore.kernel.org/all/20210713004205.775386-1-jusual@redhat.com/
>>
>>
>> Eric Auger (22):
>>    hw/i386/acpi-build: Make aml_pci_device_dsm() static
>>    hw/arm/virt: Introduce machine state acpi pcihp flags and props
>>    hw/acpi: Rename and move build_x86_acpi_pci_hotplug to pcihp
>>    hw/pci-host/gpex-acpi: Add native_pci_hotplug arg to
>>      acpi_dsdt_add_pci_osc
>>    hw/pci-host/gpex-acpi: Split host bridge OSC and DSM generation
>>    hw/pci-host/gpex-acpi: Propagate hotplug type info from virt machine
>>      downto gpex
>>    hw/i386/acpi-build: Turn build_q35_osc_method into a generic method
>>    hw/pci-host/gpex-acpi: Use build_pci_host_bridge_osc_method
>>    hw/i386/acpi-build: Introduce build_append_pcihp_resources() helper
>>    hw/acpi/pcihp: Add an AmlRegionSpace arg to build_acpi_pci_hotplug
>>    hw/i386/acpi-build: Move build_append_notification_callback to pcihp
>>    hw/i386/acpi-build: Move build_append_pci_bus_devices/pcihp_slots to
>>      pcihp
>>    hw/i386/acpi-build: Introduce and use acpi_get_pci_host
>>    hw/i386/acpi-build: Move aml_pci_edsm to a generic place
>>    hw/arm/virt-acpi-build: Modify the DSDT ACPI table to enable ACPI PCI
>>      hotplug
>>    hw/acpi/ged: Prepare the device to react to PCI hotplug events
>>    hw/acpi/ged: Call pcihp plug callbacks in hotplug handler
>>      implementation
>>    hw/acpi/ged: Support migration of AcpiPciHpState
>>    hw/core/sysbus: Introduce sysbus_mmio_map_name() helper
>>    hw/arm/virt: Let virt support pci hotplug/unplug GED event
>>    hw/arm/virt: Plug pcihp hotplug/hotunplug callbacks
>>    hw/arm/virt: Use ACPI PCI hotplug by default
>>
>>   hw/i386/acpi-build.h                   |   4 -
>>   include/hw/acpi/aml-build.h            |   2 +
>>   include/hw/acpi/generic_event_device.h |   5 +
>>   include/hw/acpi/pci.h                  |   4 +-
>>   include/hw/acpi/pcihp.h                |  19 +-
>>   include/hw/arm/virt.h                  |   4 +
>>   include/hw/pci-host/gpex.h             |   1 +
>>   include/hw/sysbus.h                    |   1 +
>>   hw/acpi/aml-build.c                    |  50 +++
>>   hw/acpi/generic_event_device.c         |  55 +++
>>   hw/acpi/pci.c                          |  20 +
>>   hw/acpi/pcihp.c                        | 482 ++++++++++++++++++++-
>>   hw/arm/virt-acpi-build.c               |  27 ++
>>   hw/arm/virt.c                          | 107 ++++-
>>   hw/core/sysbus.c                       |  11 +
>>   hw/i386/acpi-build.c                   | 552 +------------------------
>>   hw/pci-host/gpex-acpi.c                |  75 +---
>>   hw/arm/Kconfig                         |   2 +
>>   18 files changed, 806 insertions(+), 615 deletions(-)
>>
>