Re: [PATCH v3 8/9] hw/ppc: Add a test machine for the IBM PPE42 CPU

["Cédric Le Goater" <clg@redhat.com>]

On 9/8/25 22:00, Glenn Miles wrote:
> Adds a test machine for the IBM PPE42 processor, including a
> DEC, FIT, WDT and 512 KiB of ram.
> 
> The purpose of this machine is only to provide a generic platform
> for testing instructions of the recently  added PPE42 processor
> model which is used extensively in the IBM Power9, Power10 and
> future Power server processors.
> 
> Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
> ---
> 
> Changes from v2:
>    - Moved decrementer changes to distinct commit
>    - Introduced a specific MachineState for the ppe42 Machine
>    - Use qdev_realize to create the machine
>    - Use valid_cpu_types to determine validity of CPU
>    - Changed machine ram limit from 2GB to 512KB
> 
>   MAINTAINERS            |   6 +++
>   hw/ppc/Kconfig         |   9 ++++
>   hw/ppc/meson.build     |   2 +
>   hw/ppc/ppe42_machine.c | 102 +++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 119 insertions(+)
>   create mode 100644 hw/ppc/ppe42_machine.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a07086ed76..52fa303e0a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1531,6 +1531,12 @@ F: include/hw/pci-host/grackle.h
>   F: pc-bios/qemu_vga.ndrv
>   F: tests/functional/test_ppc_mac.py
>   
> +PPE42
> +M: Glenn Miles <milesg@linux.ibm.com>
> +L: qemu-ppc@nongnu.org
> +S: Odd Fixes
> +F: hw/ppc/ppe42_machine.c
> +
>   PReP
>   M: Hervé Poussineau <hpoussin@reactos.org>
>   L: qemu-ppc@nongnu.org
> diff --git a/hw/ppc/Kconfig b/hw/ppc/Kconfig
> index ced6bbc740..3fdea5919c 100644
> --- a/hw/ppc/Kconfig
> +++ b/hw/ppc/Kconfig
> @@ -44,6 +44,15 @@ config POWERNV
>       select SSI_M25P80
>       select PNV_SPI
>   
> +config PPC405
> +    bool
> +    default y
> +    depends on PPC
> +    select M48T59
> +    select PFLASH_CFI02
> +    select PPC4XX
> +    select SERIAL

Does the machine need all the above support ?

> +
>   config PPC440
>       bool
>       default y
> diff --git a/hw/ppc/meson.build b/hw/ppc/meson.build
> index 9893f8adeb..170b90ae7d 100644
> --- a/hw/ppc/meson.build
> +++ b/hw/ppc/meson.build
> @@ -57,6 +57,8 @@ ppc_ss.add(when: 'CONFIG_POWERNV', if_true: files(
>     'pnv_n1_chiplet.c',
>   ))
>   # PowerPC 4xx boards
> +ppc_ss.add(when: 'CONFIG_PPC405', if_true: files(
> +  'ppe42_machine.c'))
>   ppc_ss.add(when: 'CONFIG_PPC440', if_true: files(
>     'ppc440_bamboo.c',
>     'ppc440_uc.c'))
> diff --git a/hw/ppc/ppe42_machine.c b/hw/ppc/ppe42_machine.c
> new file mode 100644
> index 0000000000..2cfce2503f
> --- /dev/null
> +++ b/hw/ppc/ppe42_machine.c
> @@ -0,0 +1,102 @@
> +/*
> + * Test Machine for the IBM PPE42 processor
> + *
> + * Copyright (c) 2025, IBM Corporation.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/units.h"
> +#include "qemu/error-report.h"
> +#include "system/address-spaces.h"
> +#include "hw/boards.h"
> +#include "hw/ppc/ppc.h"
> +#include "system/system.h"
> +#include "system/reset.h"
> +#include "system/kvm.h"
> +#include "qapi/error.h"
> +
> +#define TYPE_PPE42_MACHINE MACHINE_TYPE_NAME("ppe42_machine")
> +typedef MachineClass Ppe42MachineClass;
> +typedef struct Ppe42MachineState Ppe42MachineState;
> +DECLARE_OBJ_CHECKERS(Ppe42MachineState, Ppe42MachineClass,
> +                     PPE42_MACHINE, TYPE_PPE42_MACHINE)
> +
> +struct Ppe42MachineState {
> +    MachineState parent_obj;
> +
> +    PowerPCCPU cpu;
> +};
> +
> +static void main_cpu_reset(void *opaque)
> +{
> +    PowerPCCPU *cpu = opaque;
> +
> +    cpu_reset(CPU(cpu));
> +}
> +
> +static void ppe42_machine_init(MachineState *machine)
> +{
> +    Ppe42MachineState *pms = PPE42_MACHINE(machine);
> +    PowerPCCPU *cpu = &pms->cpu;
> +
> +    if (kvm_enabled()) {
> +        error_report("machine %s does not support the KVM accelerator",
> +                     MACHINE_GET_CLASS(machine)->name);
> +        exit(EXIT_FAILURE);
> +    }
> +
> +    /* init CPU */
> +    object_initialize_child(OBJECT(pms), "cpu", cpu, machine->cpu_type);
> +    if (!qdev_realize(DEVICE(cpu), NULL, &error_fatal)) {
> +        return;
> +    }
> +
> +    qemu_register_reset(main_cpu_reset, cpu);
> +
> +    /* This sets the decrementer timebase */
> +    ppc_booke_timers_init(cpu, 37500000, PPC_TIMER_PPE);
> +
> +    /* RAM */
> +    if (machine->ram_size > 512 * KiB) {
> +        error_report("RAM size more than 512 KiB is not supported");
> +        exit(1);
> +    }

In case of resend, the RAM size could be tested sooner (after kvm_enabled()).

> +    memory_region_add_subregion(get_system_memory(), 0xfff80000, machine->ram);
> +}
> +
> +
> +static void ppe42_machine_class_init(ObjectClass *oc, const void *data)
> +{
> +    MachineClass *mc = MACHINE_CLASS(oc);
> +    static const char * const valid_cpu_types[] = {
> +        POWERPC_CPU_TYPE_NAME("PPE42"),
> +        POWERPC_CPU_TYPE_NAME("PPE42X"),
> +        POWERPC_CPU_TYPE_NAME("PPE42XM"),
> +        NULL,
> +    };
> +
> +    mc->desc = "PPE42 Test Machine";
> +    mc->init = ppe42_machine_init;
> +    mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("PPE42XM");
> +    mc->valid_cpu_types = valid_cpu_types;
> +    mc->default_ram_id = "ram";
> +    mc->default_ram_size = 512 * KiB;
> +}
> +
> +static const TypeInfo ppe42_machine_info = {
> +        .name          = TYPE_PPE42_MACHINE,
> +        .parent        = TYPE_MACHINE,
> +        .instance_size = sizeof(Ppe42MachineState),
> +        .class_init    = ppe42_machine_class_init,
> +        .class_size    = sizeof(Ppe42MachineClass),
> +};
> +
> +static void ppe42_machine_register_types(void)
> +{
> +    type_register_static(&ppe42_machine_info);
> +}
> +
> +type_init(ppe42_machine_register_types);
> +


Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.