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

[Gustavo Romero <gustavo.romero@linaro.org>]

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.


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(-)
>