Re: [PATCH 3/3] hw/acpi/cpu_hotplug: Convert 'Object *device' -> 'DeviceState *parent'

[Philippe Mathieu-Daudé]

On 28/2/23 22:41, Michael S. Tsirkin wrote:
> On Fri, Feb 03, 2023 at 05:30:21PM +0100, Philippe Mathieu-Daudé wrote:
> > ACPI CPU hotplug parent can't be any QOM object, it must be a QDev.
> > Convert AcpiCpuHotplug::device field as QDev to enforce this.
> > Rename 'owner' and 'device' variables as 'parent'.
> >
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>
>
> So instead of plain gpe->device we now have OBJECT all over
> the place. Why is this an improvement?

From QOM PoV, in this prototype change:

  void legacy_acpi_cpu_hotplug_init(MemoryRegion *container,
- Object *owner,
+ DeviceState *parent,

we promote the parent/owner argument from generic Object to
Device, which is more restrictive.

Thus now you can not pass any QOM object, it has to be a QDev.

> > ---
> >   hw/acpi/acpi-cpu-hotplug-stub.c |  2 +-
> >   hw/acpi/cpu_hotplug.c           | 18 +++++++++---------
> >   hw/acpi/ich9.c                  |  5 +++--
> >   hw/acpi/piix4.c                 |  2 +-
> >   include/hw/acpi/cpu_hotplug.h   |  4 ++--
> >   5 files changed, 16 insertions(+), 15 deletions(-)
> >
> > diff --git a/hw/acpi/acpi-cpu-hotplug-stub.c b/hw/acpi/acpi-cpu-hotplug-stub.c
> > index cbd7a6ec00..0fcc1ec8ea 100644
> > --- a/hw/acpi/acpi-cpu-hotplug-stub.c
> > +++ b/hw/acpi/acpi-cpu-hotplug-stub.c
> > @@ -13,7 +13,7 @@ void acpi_switch_to_modern_cphp(AcpiCpuHotplug *gpe,
> >       return;
> >   }
> >   
> > -void legacy_acpi_cpu_hotplug_init(MemoryRegion *container, Object *owner,
> > +void legacy_acpi_cpu_hotplug_init(MemoryRegion *container, DeviceState *parent,
> >                                     AcpiCpuHotplug *gpe, uint16_t base)
> >   {
> >       return;
> > diff --git a/hw/acpi/cpu_hotplug.c b/hw/acpi/cpu_hotplug.c
> > index 636e985c50..b8c9081738 100644
> > --- a/hw/acpi/cpu_hotplug.c
> > +++ b/hw/acpi/cpu_hotplug.c
> > @@ -41,8 +41,8 @@ static void cpu_status_write(void *opaque, hwaddr addr, 
> > uint64_t data,
> >        */
> >       if (addr == 0 && data == 0) {
> >           AcpiCpuHotplug *gpe = opaque;
> > -        object_property_set_bool(gpe->device, "cpu-hotplug-legacy", false,
> > -                                 &error_abort);
> > +        object_property_set_bool(OBJECT(gpe->parent), "cpu-hotplug-legacy",
> > +                                 false, &error_abort);
> >       }
> >   }
> >   
> > @@ -66,8 +66,8 @@ static void acpi_set_cpu_present_bit(AcpiCpuHotplug *gpe, CPUState *cpu)
> >   
> >       cpu_id = k->get_arch_id(cpu);
> >       if ((cpu_id / 8) >= ACPI_GPE_PROC_LEN) {
> > -        object_property_set_bool(gpe->device, "cpu-hotplug-legacy", false,
> > -                                 &error_abort);
> > +        object_property_set_bool(OBJECT(gpe->parent), "cpu-hotplug-legacy",
> > +                                 false, &error_abort);
> >           return;
> >       }
> >   
> > @@ -81,15 +81,15 @@ void legacy_acpi_cpu_plug_cb(HotplugHandler *hotplug_dev, AcpiCpuHotplug *gpe,
> >       acpi_send_event(DEVICE(hotplug_dev), ACPI_CPU_HOTPLUG_STATUS);
> >   }
> >   
> > -void legacy_acpi_cpu_hotplug_init(MemoryRegion *container, Object *owner,
> > +void legacy_acpi_cpu_hotplug_init(MemoryRegion *container, DeviceState *parent,
> >                                     AcpiCpuHotplug *gpe, uint16_t base)
> >   {
> >       CPUState *cpu;
> >   
> > -    memory_region_init_io(&gpe->io, owner, &AcpiCpuHotplug_ops,
> > +    memory_region_init_io(&gpe->io, OBJECT(parent), &AcpiCpuHotplug_ops,
> >                             gpe, "acpi-cpu-hotplug", ACPI_GPE_PROC_LEN);
> >       memory_region_add_subregion(container, base, &gpe->io);
> > -    gpe->device = owner;
> > +    gpe->parent = parent;
> >   
> >       CPU_FOREACH(cpu) {
> >           acpi_set_cpu_present_bit(gpe, cpu);
> > @@ -100,10 +100,10 @@ void acpi_switch_to_modern_cphp(AcpiCpuHotplug *gpe,
> >                                   CPUHotplugState *cpuhp_state,
> >                                   uint16_t io_port)
> >   {
> > -    MemoryRegion *container = pci_address_space_io(PCI_DEVICE(gpe->device));
> > +    MemoryRegion *container = pci_address_space_io(PCI_DEVICE(gpe->parent));
> >   
> >       memory_region_del_subregion(container, &gpe->io);
> > -    cpu_hotplug_hw_init(container, gpe->device, cpuhp_state, io_port);
> > +    cpu_hotplug_hw_init(container, OBJECT(gpe->parent), cpuhp_state, io_port);
> >   }
> >   
> >   void build_legacy_cpu_hotplug_aml(Aml *ctx, MachineState *machine,
> > diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
> > index 4f8385b894..6c9a737479 100644
> > --- a/hw/acpi/ich9.c
> > +++ b/hw/acpi/ich9.c
> > @@ -197,7 +197,7 @@ static bool vmstate_test_use_cpuhp(void *opaque)
> >   static int vmstate_cpuhp_pre_load(void *opaque)
> >   {
> >       ICH9LPCPMRegs *s = opaque;
> > -    Object *obj = OBJECT(s->gpe.device);
> > +    Object *obj = OBJECT(s->gpe.parent);
> >       object_property_set_bool(obj, "cpu-hotplug-legacy", false, &error_abort);
> >       return 0;
> >   }
> > @@ -338,7 +338,8 @@ void ich9_pm_init(PCIDevice *lpc_pci, ICH9LPCPMRegs *pm,
> >       qemu_register_powerdown_notifier(&pm->powerdown_notifier);
> >   
> >       legacy_acpi_cpu_hotplug_init(pci_address_space_io(lpc_pci),
> > -        OBJECT(lpc_pci), &pm->gpe, ICH9_CPU_HOTPLUG_IO_BASE);
> > +                                 DEVICE(lpc_pci), &pm->gpe,
> > +                                 ICH9_CPU_HOTPLUG_IO_BASE);
> >   
> >       if (pm->acpi_memory_hotplug.is_enabled) {
> >           acpi_memory_hotplug_init(pci_address_space_io(lpc_pci), 
> > OBJECT(lpc_pci),
> > diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
> > index 5595fe5be5..3a61d89f92 100644
> > --- a/hw/acpi/piix4.c
> > +++ b/hw/acpi/piix4.c
> > @@ -571,7 +571,7 @@ static void piix4_acpi_system_hot_add_init(MemoryRegion 
> > *container,
> >       object_property_add_bool(OBJECT(s), "cpu-hotplug-legacy",
> >                                piix4_get_cpu_hotplug_legacy,
> >                                piix4_set_cpu_hotplug_legacy);
> > -    legacy_acpi_cpu_hotplug_init(container, OBJECT(s), &s->gpe,
> > +    legacy_acpi_cpu_hotplug_init(container, DEVICE(s), &s->gpe,
> >                                    PIIX4_CPU_HOTPLUG_IO_BASE);
> >   
> >       if (s->acpi_memory_hotplug.is_enabled) {
> > diff --git a/include/hw/acpi/cpu_hotplug.h b/include/hw/acpi/cpu_hotplug.h
> > index 5ff24ec417..b2f990f0b8 100644
> > --- a/include/hw/acpi/cpu_hotplug.h
> > +++ b/include/hw/acpi/cpu_hotplug.h
> > @@ -20,7 +20,7 @@
> >   #include "hw/acpi/cpu.h"
> >   
> >   typedef struct AcpiCpuHotplug {
> > -    Object *device;
> > +    DeviceState *parent;
> >       MemoryRegion io;
> >       uint8_t sts[ACPI_GPE_PROC_LEN];
> >   } AcpiCpuHotplug;
> > @@ -28,7 +28,7 @@ typedef struct AcpiCpuHotplug {
> >   void legacy_acpi_cpu_plug_cb(HotplugHandler *hotplug_dev, AcpiCpuHotplug *gpe,
> >                                DeviceState *dev, Error **errp);
> >   
> > -void legacy_acpi_cpu_hotplug_init(MemoryRegion *container, Object *owner,
> > +void legacy_acpi_cpu_hotplug_init(MemoryRegion *container, DeviceState *parent,
> >                                     AcpiCpuHotplug *gpe, uint16_t base);
> >   
> >   void acpi_switch_to_modern_cphp(AcpiCpuHotplug *gpe,
> > --
> > 2.38.1