Re: [PATCH v3 20/29] hw/acpi/ged: Prepare the device to react to PCI hotplug events

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 16 Jun 2025 11:46:49 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> QEMU will notify the OS about PCI hotplug/hotunplug events through
> GED interrupts. Let the GED device handle a new PCI hotplug event.
> On its occurrence it calls the \\_SB.PCI0.PCNT method with the BLCK
> mutex held.
> 
> The GED device uses a dedicated MMIO region that will be mapped
> by the machine code.


> At this point the GED still does not support PCI device hotplug in
> its TYPE_HOTPLUG_HANDLER implementation. This will come in a
> subsequent patch.

looks out of order, perhaps it should be before this patch

> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> 
> ---
> v2 -> v3:
> - pcihp_init and reset are put in ged code instead of machine code
>   (Igor)
> 
> v1 -> v2:
> - Introduce ACPI_PCIHP_REGION_NAME
> ---
>  include/hw/acpi/generic_event_device.h |  4 ++++
>  hw/acpi/generic_event_device.c         | 26 ++++++++++++++++++++++++++
>  hw/acpi/pcihp.c                        |  1 -
>  3 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/include/hw/acpi/generic_event_device.h b/include/hw/acpi/generic_event_device.h
> index f5ffa67a39..ec8e1abe0a 100644
> --- a/include/hw/acpi/generic_event_device.h
> +++ b/include/hw/acpi/generic_event_device.h
> @@ -102,6 +102,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(AcpiGedState, ACPI_GED)
>  #define ACPI_GED_PWR_DOWN_EVT      0x2
>  #define ACPI_GED_NVDIMM_HOTPLUG_EVT 0x4
>  #define ACPI_GED_CPU_HOTPLUG_EVT    0x8
> +#define ACPI_GED_PCI_HOTPLUG_EVT    0x10
>  
>  typedef struct GEDState {
>      MemoryRegion evt;
> @@ -109,6 +110,8 @@ typedef struct GEDState {
>      uint32_t     sel;
>  } GEDState;
>  
> +#define ACPI_PCIHP_REGION_NAME "pcihp container"
> +
>  struct AcpiGedState {
>      SysBusDevice parent_obj;
>      MemHotplugState memhp_state;
> @@ -116,6 +119,7 @@ struct AcpiGedState {
>      CPUHotplugState cpuhp_state;
>      MemoryRegion container_cpuhp;
>      AcpiPciHpState pcihp_state;
> +    MemoryRegion container_pcihp;
>      GEDState ged_state;
>      uint32_t ged_event_bitmap;
>      qemu_irq irq;
> diff --git a/hw/acpi/generic_event_device.c b/hw/acpi/generic_event_device.c
> index ef1c1ec51f..b4eefb0106 100644
> --- a/hw/acpi/generic_event_device.c
> +++ b/hw/acpi/generic_event_device.c
> @@ -12,6 +12,7 @@
>  #include "qemu/osdep.h"
>  #include "qapi/error.h"
>  #include "hw/acpi/acpi.h"
> +#include "hw/acpi/pcihp.h"
>  #include "hw/acpi/generic_event_device.h"
>  #include "hw/pci/pci.h"
>  #include "hw/irq.h"
> @@ -27,6 +28,7 @@ static const uint32_t ged_supported_events[] = {
>      ACPI_GED_PWR_DOWN_EVT,
>      ACPI_GED_NVDIMM_HOTPLUG_EVT,
>      ACPI_GED_CPU_HOTPLUG_EVT,
> +    ACPI_GED_PCI_HOTPLUG_EVT,
>  };
>  
>  /*
> @@ -122,6 +124,12 @@ void build_ged_aml(Aml *table, const char *name, HotplugHandler *hotplug_dev,
>                             aml_notify(aml_name("\\_SB.NVDR"),
>                                        aml_int(0x80)));
>                  break;
> +            case ACPI_GED_PCI_HOTPLUG_EVT:
> +                aml_append(if_ctx,
> +                           aml_acquire(aml_name("\\_SB.PCI0.BLCK"), 0xFFFF));
> +                aml_append(if_ctx, aml_call0("\\_SB.PCI0.PCNT"));
> +                aml_append(if_ctx, aml_release(aml_name("\\_SB.PCI0.BLCK")));
> +                break;
>              default:
>                  /*
>                   * Please make sure all the events in ged_supported_events[]
> @@ -300,6 +308,8 @@ static void acpi_ged_send_event(AcpiDeviceIf *adev, AcpiEventStatusBits ev)
>          sel = ACPI_GED_NVDIMM_HOTPLUG_EVT;
>      } else if (ev & ACPI_CPU_HOTPLUG_STATUS) {
>          sel = ACPI_GED_CPU_HOTPLUG_EVT;
> +    } else if (ev & ACPI_PCI_HOTPLUG_STATUS) {
> +        sel = ACPI_GED_PCI_HOTPLUG_EVT;
>      } else {
>          /* Unknown event. Return without generating interrupt. */
>          warn_report("GED: Unsupported event %d. No irq injected", ev);
> @@ -433,6 +443,12 @@ static void acpi_ged_realize(DeviceState *dev, Error **errp)
>              cpu_hotplug_hw_init(&s->container_cpuhp, OBJECT(dev),
>                                  &s->cpuhp_state, 0);
>              break;
> +        case ACPI_GED_PCI_HOTPLUG_EVT:
> +            memory_region_init(&s->container_pcihp, OBJECT(dev),
> +                               ACPI_PCIHP_REGION_NAME, ACPI_PCIHP_SIZE);
> +            sysbus_init_mmio(sbd, &s->container_pcihp);
> +            acpi_pcihp_init(OBJECT(s), &s->pcihp_state,
> +                            s->pcihp_state.root, &s->container_pcihp, 0);
>          }
>          ged_events--;
>      }
> @@ -474,6 +490,15 @@ static void acpi_ged_initfn(Object *obj)
>      sysbus_init_mmio(sbd, &ged_st->regs);
>  }
>  
> +static void ged_reset(DeviceState *dev)
> +{
> +    AcpiGedState *s = ACPI_GED(dev);
> +
> +    if (s->pcihp_state.use_acpi_hotplug_bridge) {
> +        acpi_pcihp_reset(&s->pcihp_state);
> +    }
> +}
> +
>  static void acpi_ged_class_init(ObjectClass *class, const void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(class);
> @@ -488,6 +513,7 @@ static void acpi_ged_class_init(ObjectClass *class, const void *data)
>      hc->plug = acpi_ged_device_plug_cb;
>      hc->unplug_request = acpi_ged_unplug_request_cb;
>      hc->unplug = acpi_ged_unplug_cb;
> +    device_class_set_legacy_reset(dc, ged_reset);
>  
>      adevc->ospm_status = acpi_ged_ospm_status;
>      adevc->send_event = acpi_ged_send_event;
> diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
> index e79a24b821..36492aa0d9 100644
> --- a/hw/acpi/pcihp.c
> +++ b/hw/acpi/pcihp.c
> @@ -43,7 +43,6 @@
>  #include "qobject/qnum.h"
>  #include "trace.h"
>  
> -#define ACPI_PCIHP_SIZE 0x0018
>  #define PCI_UP_BASE 0x0000
>  #define PCI_DOWN_BASE 0x0004
>  #define PCI_EJ_BASE 0x0008