Re: [Qemu-ppc] [PATCH v3 07/22] memory-device: add and use memory_device_get_region_size()

[David Gibson]

On Mon, Sep 24, 2018 at 11:03:35AM +0200, David Hildenbrand wrote:
> On 21/09/2018 10:38, David Gibson wrote:
> > On Fri, Sep 21, 2018 at 09:15:09AM +0200, David Hildenbrand wrote:
> >>
> >>>>  
> >>>> -    mr = ddc->get_memory_region(dimm, errp);
> >>>> -    if (!mr) {
> >>>> +    value = memory_device_get_region_size(MEMORY_DEVICE(obj), errp);
> >>>
> >>> Given the below, that should be &local_err above, no?
> >>
> >> Yes, very right!
> >>
> >>>
> >>>> +    if (local_err) {
> >>>> +        error_propagate(errp, local_err);
> >>>>          return;
> >>>>      }
> >>>> -    value = memory_region_size(mr);
> >>>>  
> >>>>      visit_type_uint64(v, name, &value, errp);
> >>>>  }
> >>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> >>>> index 4edb6c7d16..b56ce6b7aa 100644
> >>>> --- a/hw/ppc/spapr.c
> >>>> +++ b/hw/ppc/spapr.c
> >>>> @@ -3124,20 +3124,17 @@ static void spapr_memory_plug(HotplugHandler 
> >>>> *hotplug_dev, DeviceState *dev,
> >>>>  {
> >>>>      Error *local_err = NULL;
> >>>>      sPAPRMachineState *ms = SPAPR_MACHINE(hotplug_dev);
> >>>> -    PCDIMMDevice *dimm = PC_DIMM(dev);
> >>>> -    PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> >>>> -    MemoryRegion *mr = ddc->get_memory_region(dimm, &error_abort);
> >>>>      uint64_t size, addr;
> >>>>      uint32_t node;
> >>>>  
> >>>> -    size = memory_region_size(mr);
> >>>> +    size = memory_device_get_region_size(MEMORY_DEVICE(dev), 
> >>>> &error_abort);
> >>>>  
> >>>>      pc_dimm_plug(dev, MACHINE(ms), &local_err);
> >>>>      if (local_err) {
> >>>>          goto out;
> >>>>      }
> >>>>  
> >>>> -    addr = object_property_get_uint(OBJECT(dimm),
> >>>> +    addr = object_property_get_uint(OBJECT(dev),
> >>>>                                      PC_DIMM_ADDR_PROP, &local_err);
> >>>
> >>> It bothers me a bit that we're no longer explicitly forcing this to be
> >>> a DIMM object pointer, but we're still using PC_DIMM_ADDR_PROP.
> >>
> >> Well, OBJECT(PC_DIMM(dev))) looks stange and should not be necessary.
> >>
> >> We could do a g_assert(object_dynamic_cast(dimm, TYPE_PC_DIMM)) above
> >> the function. What do you think?
> >>
> >> We could also do a memory-device::get_addr() instead of going via the
> >> property. What do you think?
> > 
> > I think that's a better idea.
> > 
> 
> Hmm, but looking at spapr_memory_plug(), we already get the node via
> OBJECT(dev). And in spapr_memory_pre_plug(), we get the memdev. We are
> not able to access these properties via the memory device interface.
> 
> So I guess adding assertions
> 
> g_assert(object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM));
> 
> Would be the right thing to do. On the other hand, these two static
> functions are already called "if (object_dynamic_cast(OBJECT(dev),
> TYPE_PC_DIMM))".
> 
> However, I guess I will go another path: Make pc_dimm_plug() and friends
> eat a TYPE_PC_DIMM instead of a TYPE_DEVICE. Then this cast will not go
> away. Problem solved :)

In the short term, yes.  We will want to generalize the PAPR hotplug
code to memory devices other than PC DIMM in the fairly near future,
though.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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