Re: [PATCH v3 26/29] hw/arm/virt: Plug pcihp hotplug/hotunplug callbacks

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Mon, 16 Jun 2025 11:46:55 +0200
Eric Auger <eric.auger@redhat.com> wrote:

Maybe needs a little bit of description.

> Signed-off-by: Eric Auger <eric.auger@redhat.com>

A few trivial things inline.
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> 
> ---
> v2 -> v3:
> - fix cohabitation with virtio-mem-pci device and tested
>   hotplug/unplug of this latter (Igor)
> ---
>  hw/arm/virt.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 69 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 8c882e0794..06b87e1050 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1747,6 +1747,22 @@ static void virt_build_smbios(VirtMachineState *vms)
>      }
>  }
>  
> +static AcpiPciHpState *get_acpi_pcihp_state(VirtMachineState *vms)
> +{
> +    AcpiGedState *acpi_ged_state;
> +    AcpiPciHpState *pcihp_state;
> +
> +    if (!vms->acpi_dev) {
> +        return NULL;
> +    }
> +    acpi_ged_state = ACPI_GED(vms->acpi_dev);
> +    pcihp_state = &acpi_ged_state->pcihp_state;
> +    if (pcihp_state->use_acpi_hotplug_bridge) {
> +        return pcihp_state;
> +    }
> +    return NULL;

Really trivial but if this isn't going to gain extra stuff I'd consider
the NULL return the 'error' path and prefer that out of line for consistency.
That is.

    if(!pcihp_state->use_acpi_hotplug_bridge) {
        return NULL;
    }

    return pcihp_state;


That just ends up a tiny bit more consistent with the !vms->acpi_dev test
earlier in the function.

> +}
> +
>  static
>  void virt_machine_done(Notifier *notifier, void *data)
>  {
> @@ -2907,6 +2923,13 @@ static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>  {
>      VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
>  

Maybe add a comment on why this is not in the if/else stack.  I assume
because a few of those are also TYPE_PCI_DEVICE.
Something in the patch description would also work for me.

> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> +        if (get_acpi_pcihp_state(vms)) {
> +            acpi_pcihp_device_pre_plug_cb(HOTPLUG_HANDLER(vms->acpi_dev),
> +                                          dev, errp);
> +        }
> +    }
> +
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_memory_pre_plug(hotplug_dev, dev, errp);
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
> @@ -2961,6 +2984,15 @@ static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
>          }
>      }
>  
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> +        AcpiPciHpState *pcihp_state = get_acpi_pcihp_state(vms);
> +
> +        if (pcihp_state) {
> +            acpi_pcihp_device_plug_cb(HOTPLUG_HANDLER(vms->acpi_dev),
> +                                      pcihp_state, dev, errp);
> +        }
> +    }
> +
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_memory_plug(hotplug_dev, dev, errp);
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
> @@ -3017,12 +3049,27 @@ out:
>  static void virt_machine_device_unplug_request_cb(HotplugHandler *hotplug_dev,
>                                            DeviceState *dev, Error **errp)
>  {
> +    bool supported = false;
> +
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_dimm_unplug_request(hotplug_dev, dev, errp);
> +        supported = true;
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
>          virtio_md_pci_unplug_request(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev),
>                                       errp);
> -    } else {
> +        supported = true;
> +    }
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> +        VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> +        AcpiPciHpState *pcihp_state = get_acpi_pcihp_state(vms);
> +
> +        if (pcihp_state) {
> +            acpi_pcihp_device_unplug_request_cb(HOTPLUG_HANDLER(vms->acpi_dev),
> +                                                pcihp_state, dev, errp);
> +            supported = true;
> +        }
> +    }
> +    if (!supported) {
>          error_setg(errp, "device unplug request for unsupported device"
>                     " type: %s", object_get_typename(OBJECT(dev)));
>      }
> @@ -3031,11 +3078,27 @@ static void virt_machine_device_unplug_request_cb(HotplugHandler *hotplug_dev,
>  static void virt_machine_device_unplug_cb(HotplugHandler *hotplug_dev,
>                                            DeviceState *dev, Error **errp)
>  {
> +    bool supported = false;
> +
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_dimm_unplug(hotplug_dev, dev, errp);
> +        supported = true;
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
>          virtio_md_pci_unplug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
> -    } else {
> +        supported = true;
> +    }
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> +        VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> +
> +        AcpiPciHpState *pcihp_state = get_acpi_pcihp_state(vms);
> +
> +        if (pcihp_state) {
> +            acpi_pcihp_device_unplug_cb(HOTPLUG_HANDLER(vms->acpi_dev),
> +                                        pcihp_state, dev, errp);
> +            supported = true;
> +        }
> +    }
> +    if (!supported) {
>          error_setg(errp, "virt: device unplug for unsupported device"
>                     " type: %s", object_get_typename(OBJECT(dev)));
>      }