Re: [Qemu-devel] [PATCH v4] i386, acpi: check acpi_memory_hotplug capacity in pre_plug

[Wei Yang]

On Thu, Feb 21, 2019 at 03:45:51PM +0100, Igor Mammedov wrote:
>On Tue, 19 Feb 2019 16:08:26 +0800
>Wei Yang <address@hidden> wrote:
>
>> Currently we do device realization like below:
>> 
>>    hotplug_handler_pre_plug()
>>    dc->realize()
>>    hotplug_handler_plug()
>> 
>> Before we do device realization and plug, we should allocate necessary
>> resources and check if memory-hotplug-support property is enabled.
>> 
>> At the piix4 and ich9, the memory-hotplug-support property is checked at
>> plug stage. This means that device has been realized and mapped into guest
>> address space 'pc_dimm_plug()' by the time acpi plug handler is called,
>> where it might fail and crash QEMU due to reaching g_assert_not_reached()
>> (piix4) or error_abort (ich9).
>> 
>> Fix it by checking if memory hotplug is enabled at pre_plug stage
>> where we can gracefully abort hotplug request.
>> 
>> Signed-off-by: Wei Yang <address@hidden>
>> CC: Igor Mammedov <address@hidden>
>> CC: Eric Blake <address@hidden>
>patch refuses to be applied to current master

Let me fetch the latest code.

>
>> 
>> ---
>> v4:
>>    * fix code alignment of piix4_device_pre_plug_cb
>> v3:
>>    * replace acpi_memory_hotplug with memory-hotplug-support in changelog
>>    * fix code alignment of ich9_pm_device_pre_plug_cb
>>    * print which device type memory-hotplug-support is disabled in
>>      ich9_pm_device_pre_plug_cb and piix4_device_pre_plug_cb
>> v2:
>>    * (address@hidden)
>>      - Almost the whole third paragraph
>>    * apply this change to ich9
>>    * use hotplug_handler_pre_plug() instead of open-coding check
>> ---
>>  hw/acpi/ich9.c         | 15 +++++++++++++--
>>  hw/acpi/piix4.c        | 15 +++++++++++++--
>>  hw/i386/pc.c           |  5 +++++
>>  hw/isa/lpc_ich9.c      |  1 +
>>  include/hw/acpi/ich9.h |  2 ++
>>  5 files changed, 34 insertions(+), 4 deletions(-)
>> 
>> diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
>> index c5d8646abc..e53dfe1ee3 100644
>> --- a/hw/acpi/ich9.c
>> +++ b/hw/acpi/ich9.c
>> @@ -483,13 +483,24 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs 
>> *pm, Error **errp)
>>                               NULL);
>>  }
>>  
>> +void ich9_pm_device_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState 
>> *dev,
>> +                                Error **errp)
>> +{
>> +    ICH9LPCState *lpc = ICH9_LPC_DEVICE(hotplug_dev);
>> +
>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
>> +        !lpc->pm.acpi_memory_hotplug.is_enabled)
>> +        error_setg(errp,
>> +                   "memory hotplug is not enabled: 
>> %s.memory-hotplug-support "
>> +                   "is not set", object_get_typename(OBJECT(lpc)));
>> +}
>> +
>>  void ich9_pm_device_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
>>                              Error **errp)
>>  {
>>      ICH9LPCState *lpc = ICH9_LPC_DEVICE(hotplug_dev);
>>  
>> -    if (lpc->pm.acpi_memory_hotplug.is_enabled &&
>> -        object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>>          if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
>>              nvdimm_acpi_plug_cb(hotplug_dev, dev);
>>          } else {
>> diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
>> index e330f24c71..699aca630e 100644
>> --- a/hw/acpi/piix4.c
>> +++ b/hw/acpi/piix4.c
>> @@ -370,13 +370,23 @@ static void piix4_pm_powerdown_req(Notifier *n, void 
>> *opaque)
>>      acpi_pm1_evt_power_down(&s->ar);
>>  }
>>  
>> +static void piix4_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>> +                                     DeviceState *dev, Error **errp)
>> +{
>> +    PIIX4PMState *s = PIIX4_PM(hotplug_dev);
>> +
>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
>> +        !s->acpi_memory_hotplug.is_enabled)
>> +        error_setg(errp,
>> +                   "memory hotplug is not enabled: 
>> %s.memory-hotplug-support "
>> +                   "is not set", object_get_typename(OBJECT(s)));
>> +}
>>  static void piix4_device_plug_cb(HotplugHandler *hotplug_dev,
>>                                   DeviceState *dev, Error **errp)
>>  {
>>      PIIX4PMState *s = PIIX4_PM(hotplug_dev);
>>  
>> -    if (s->acpi_memory_hotplug.is_enabled &&
>> -        object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>>          if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
>>              nvdimm_acpi_plug_cb(hotplug_dev, dev);
>>          } else {
>> @@ -702,6 +712,7 @@ static void piix4_pm_class_init(ObjectClass *klass, void 
>> *data)
>>       */
>>      dc->user_creatable = false;
>>      dc->hotpluggable = false;
>> +    hc->pre_plug = piix4_device_pre_plug_cb;
>>      hc->plug = piix4_device_plug_cb;
>>      hc->unplug_request = piix4_device_unplug_request_cb;
>>      hc->unplug = piix4_device_unplug_cb;
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index 0f61314b79..0b11ebe2c9 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -1674,6 +1674,11 @@ static void pc_memory_pre_plug(HotplugHandler 
>> *hotplug_dev, DeviceState *dev,
>>          return;
>>      }
>>  
>> +    /*
>> +     * Check acpi_dev memory-hotplug-support property
>> +     */
>I'd drop this comment, it's internal businesses of acpi_dev
>

Will drop this in next version.

>> +    hotplug_handler_pre_plug(pcms->acpi_dev, dev, errp);
>> +
>>      if (is_nvdimm && !pcms->acpi_nvdimm_state.is_enabled) {
>>          error_setg(errp, "nvdimm is not enabled: missing 'nvdimm' in '-M'");
>>          return;
>> diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
>> index e692b9fdc1..ac44aa53be 100644
>> --- a/hw/isa/lpc_ich9.c
>> +++ b/hw/isa/lpc_ich9.c
>> @@ -805,6 +805,7 @@ static void ich9_lpc_class_init(ObjectClass *klass, void 
>> *data)
>>       * pc_q35_init()
>>       */
>>      dc->user_creatable = false;
>> +    hc->pre_plug = ich9_pm_device_pre_plug_cb;
>>      hc->plug = ich9_pm_device_plug_cb;
>>      hc->unplug_request = ich9_pm_device_unplug_request_cb;
>>      hc->unplug = ich9_pm_device_unplug_cb;
>> diff --git a/include/hw/acpi/ich9.h b/include/hw/acpi/ich9.h
>> index 59aeb06393..428af0b0be 100644
>> --- a/include/hw/acpi/ich9.h
>> +++ b/include/hw/acpi/ich9.h
>> @@ -74,6 +74,8 @@ extern const VMStateDescription vmstate_ich9_pm;
>>  
>>  void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm, Error **errp);
>>  
>> +void ich9_pm_device_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState 
>> *dev,
>> +                            Error **errp);
>wrong alignment?
>

Hmm... you are right. Will fix it.

>>  void ich9_pm_device_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
>>                              Error **errp);
>>  void ich9_pm_device_unplug_request_cb(HotplugHandler *hotplug_dev,

-- 
Wei Yang
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