Re: [Qemu-devel] [PATCH v2] i386, acpi: check acpi_memory_hotplug capacity in pre_plug

[Wei Yang <richard.weiyang@gmail.com>]

On Mon, Feb 18, 2019 at 01:56:02PM +0100, Igor Mammedov wrote:
>On Mon, 18 Feb 2019 12:13:24 +0000
>Wei Yang <richard.weiyang@gmail.com> wrote:
>
>> On Mon, Feb 18, 2019 at 10:50:34AM +0100, Igor Mammedov wrote:
>> >On Mon, 18 Feb 2019 09:13:33 +0800
>> >Wei Yang <richardw.yang@linux.intel.com> 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 acpi_memory_hotplug property is checked in
>> >                             ^^^^^^^ is field name and not a property so
>> >s/acpi_memory_hotplug/memory-hotplug-support/
>> >s/in/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).
>> >
>> >
>> >> This patch abstract the check on acpi_memory_hotplug capacity in
>> >> pre_plug stage.
>> >maybe better would be:
>> >"Fix it by checking if memory hotplug is enabled at pre_plug stage
>> >where we can gracefully abort hotplug request."
>> >
>> >> [changelog rephrase from imammedo@redhat.com]
>> >this provides zero information for a commit reader,
>> >it should go under --- to chagelog
>> > 
>> 
>> Ok, maybe different community has different convention.
>> 
>> Linux kernel mm subsystem maintainer suggest me to add above line.
>> 
>> >> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>> >> CC: Igor Mammedov <imammedo@redhat.com>
>> >> CC: Eric Blake <eblake@redhat.com>
>> >> 
>> >> ---
>> >> v2:
>> >>    * rephrase change log
>> >one usually adds commenter's name here
>> >   * like this (someone@foo.bar)
>> >or
>> >   * (someone@foo.bar)
>> >     - entry 1
>> >     - entry 2
>> >   * (someone-else@foo.bar)
>> >     - ...
>> >
>> 
>> Well, I would change to this style.
>> 
>> >>    * apply this change to ich9
>> >>    * use hotplug_handler_pre_plug() instead of open-coding check
>> >> ---
>> >>  hw/acpi/ich9.c         | 14 ++++++++++++--
>> >>  hw/acpi/piix4.c        | 14 ++++++++++++--
>> >>  hw/i386/pc.c           |  5 +++++
>> >>  hw/isa/lpc_ich9.c      |  1 +
>> >>  include/hw/acpi/ich9.h |  2 ++
>> >>  5 files changed, 32 insertions(+), 4 deletions(-)
>> >> 
>> >> diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
>> >> index c5d8646abc..906a10f09a 100644
>> >> --- a/hw/acpi/ich9.c
>> >> +++ b/hw/acpi/ich9.c
>> >> @@ -483,13 +483,23 @@ 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)
>> >broken alignment?
>> >
>> >run /scripts/checkpatch.pl on patches before submitting them
>> 
>> I copied this from ich9_pm_device_plug_cb(), so thought this is the
>> correct style.
>> 
>> Will adjust this according to checkpatch.pl.
>
>see CODING_STYLE
>

Went throught this file, but not find the description of function
definition's second line.

I guess it should start after '(', right?

>> 
>> >
>> >> +{
>> >> +    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: ICH9 memory hotplug disabled");
>> >I'd give a hint where it's disabled, something like
>> >
>> >"memory hotplug is not enabled: %s.memory-hotplug-support is not set", object_get_typename(lpc)
>> >
>> >the same for piix4
>> >
>> >> +}
>> >> +
>> >>  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..c97b747496 100644
>> >> --- a/hw/acpi/piix4.c
>> >> +++ b/hw/acpi/piix4.c
>> >> @@ -370,13 +370,22 @@ 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: PIIX4 memory hotplug disabled");
>> >> +}
>> >>  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 +711,7 @@ 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 734d3268fa..59c8ccf0ff 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
>> >> +     */
>> >> +    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);
>> >>  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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