Re: [PATCH v2] arm/virt: Add memory hot remove support

[Auger Eric]

Hi Shameer,

On 6/17/20 6:40 PM, Shameerali Kolothum Thodi wrote:
> Hi Eric,
> 
>> -----Original Message-----
>> From: Auger Eric [mailto:eric.auger@redhat.com]
>> Sent: 17 June 2020 14:54
>> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
>> qemu-devel@nongnu.org; qemu-arm@nongnu.org
>> Cc: imammedo@redhat.com; peter.maydell@linaro.org; mst@redhat.com;
>> xuwei (O) <xuwei5@huawei.com>; Zengtao (B) <prime.zeng@hisilicon.com>;
>> Linuxarm <linuxarm@huawei.com>
>> Subject: Re: [PATCH v2] arm/virt: Add memory hot remove support
>>
>> Hi Shameer,
>>
>> On 5/20/20 1:03 PM, Shameer Kolothum wrote:
>>> This adds support for memory hot remove on arm/virt that
>>> uses acpi ged device.
>>>
>>> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
>>> ---
>>> RFC v1 --> v2
>>>   -Rebased on top of latest Qemu master.
>>>   -Dropped "RFC" and tested with kernel 5.7-rc6
>>> ---
>>>  hw/acpi/generic_event_device.c | 28 +++++++++++++++++
>>>  hw/arm/virt.c                  | 56
>> ++++++++++++++++++++++++++++++++--
>>>  2 files changed, 82 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/hw/acpi/generic_event_device.c
>> b/hw/acpi/generic_event_device.c
>>> index b1cbdd86b6..2b3bedcd2f 100644
>>> --- a/hw/acpi/generic_event_device.c
>>> +++ b/hw/acpi/generic_event_device.c
>>> @@ -193,6 +193,32 @@ static void
>> acpi_ged_device_plug_cb(HotplugHandler *hotplug_dev,
>>>      }
>>>  }
>>>
>>> +static void acpi_ged_unplug_request_cb(HotplugHandler *hotplug_dev,
>>> +                                       DeviceState *dev, Error
>> **errp)
>>> +{
>>> +    AcpiGedState *s = ACPI_GED(hotplug_dev);
>>> +
>>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>>> +        acpi_memory_unplug_request_cb(hotplug_dev,
>> &s->memhp_state, dev, errp);
>> is it allowed to unplug NVDIMM? As NVDIMM inherits from PCDIMM, I wonder
>> if we have to handle the case differently (as done in hotplug part).
> 
> True. This patch requires NVDMM check. I think when I sent out the initial RFC
> NVDIMM hot add was not merged and I forgot to update it. My bad.
> 
> But not sure we need to add the check here if we take care that in
> virt_machine_device_unplug_request_cb() as you have noted below. Do we?

I think I would, in case the GED were instantiated by another machine
that wouldn't have handled the case.
>  
>>> +    } else {
>>> +        error_setg(errp, "acpi: device unplug request for unsupported
>> device"
>>> +                   " type: %s", object_get_typename(OBJECT(dev)));
>>> +    }
>>> +}
>>> +
>>> +static void acpi_ged_unplug_cb(HotplugHandler *hotplug_dev,
>>> +                               DeviceState *dev, Error **errp)
>>> +{
>>> +    AcpiGedState *s = ACPI_GED(hotplug_dev);
>>> +
>>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>>> +        acpi_memory_unplug_cb(&s->memhp_state, dev, errp);
>>> +    } else {
>>> +        error_setg(errp, "acpi: device unplug for unsupported device"
>>> +                   " type: %s", object_get_typename(OBJECT(dev)));
>>> +    }
>>> +}
>>> +
>>>  static void acpi_ged_send_event(AcpiDeviceIf *adev, AcpiEventStatusBits
>> ev)
>>>  {
>>>      AcpiGedState *s = ACPI_GED(adev);
>>> @@ -318,6 +344,8 @@ static void acpi_ged_class_init(ObjectClass *class,
>> void *data)
>>>      dc->vmsd = &vmstate_acpi_ged;
>>>
>>>      hc->plug = acpi_ged_device_plug_cb;
>>> +    hc->unplug_request = acpi_ged_unplug_request_cb;
>>> +    hc->unplug = acpi_ged_unplug_cb;
>>>
>>>      adevc->send_event = acpi_ged_send_event;
>>>  }
>>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>>> index 37462a6f78..110fa73990 100644
>>> --- a/hw/arm/virt.c
>>> +++ b/hw/arm/virt.c
>>> @@ -2177,11 +2177,62 @@ static void
>> virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
>>>      }
>>>  }
>>>
>>> +static void virt_dimm_unplug_request(HotplugHandler *hotplug_dev,
>>> +                                     DeviceState *dev, Error
>> **errp)
>>> +{
>>> +    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
>>> +    Error *local_err = NULL;
>>> +
>>> +    if (!vms->acpi_dev) {
>>> +        error_setg(errp,
>>> +                   "memory hotplug is not enabled: missing acpi-ged
>> device");
>>> +        goto out;
>>> +    }
>>> +
>>> +    hotplug_handler_unplug_request(HOTPLUG_HANDLER(vms->acpi_dev),
>> dev,
>>> +                                   &local_err);
>>> +out:
>>> +    error_propagate(errp, local_err);
>>> +}
>>> +
>>> +static void virt_dimm_unplug(HotplugHandler *hotplug_dev,
>>> +                             DeviceState *dev, Error **errp)
>>> +{
>>> +    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
>>> +    Error *local_err = NULL;
>>> +
>>> +    hotplug_handler_unplug(HOTPLUG_HANDLER(vms->acpi_dev), dev,
>> &local_err);
>>> +    if (local_err) {
>>> +        goto out;
>>> +    }
>>> +
>>> +    pc_dimm_unplug(PC_DIMM(dev), MACHINE(vms));
>>> +    object_property_set_bool(OBJECT(dev), false, "realized", NULL);
>>> +
>>> + out:
>>> +    error_propagate(errp, local_err);
>>> +}
>>> +
>>>  static void virt_machine_device_unplug_request_cb(HotplugHandler
>> *hotplug_dev,
>>>                                            DeviceState *dev, Error
>> **errp)
>>>  {
>>> -    error_setg(errp, "device unplug request for unsupported device"
>>> -               " type: %s", object_get_typename(OBJECT(dev)));
>>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>> same here. By comparison, in hw/i386/pc.c, it is said
>> "nvdimm device hot unplug is not supported yet."
> 
> Sure. I will change it.
> 
>> what is the situation on ARM?
> 
> I don’t think it supports it. I will check.
OK

Thanks

Eric
> 
> Thanks,
> Shameer
>  
>> Thanks
>>
>> Eric
>>> +        virt_dimm_unplug_request(hotplug_dev, dev, errp);
>>> +    } else {
>>> +        error_setg(errp, "device unplug request for unsupported device"
>>> +                   " type: %s", object_get_typename(OBJECT(dev)));
>>> +    }
>>> +}
>>> +
>>> +static void virt_machine_device_unplug_cb(HotplugHandler *hotplug_dev,
>>> +                                          DeviceState *dev, Error
>> **errp)
>>> +{
>>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>>> +        virt_dimm_unplug(hotplug_dev, dev, errp);
>>> +    } else {
>>> +        error_setg(errp, "virt: device unplug for unsupported device"
>>> +                   " type: %s", object_get_typename(OBJECT(dev)));
>>> +    }
>>>  }
>>>
>>>  static HotplugHandler *virt_machine_get_hotplug_handler(MachineState
>> *machine,
>>> @@ -2262,6 +2313,7 @@ static void virt_machine_class_init(ObjectClass
>> *oc, void *data)
>>>      hc->pre_plug = virt_machine_device_pre_plug_cb;
>>>      hc->plug = virt_machine_device_plug_cb;
>>>      hc->unplug_request = virt_machine_device_unplug_request_cb;
>>> +    hc->unplug = virt_machine_device_unplug_cb;
>>>      mc->numa_mem_supported = true;
>>>      mc->nvdimm_supported = true;
>>>      mc->auto_enable_numa_with_memhp = true;
>>>
>