Re: [Qemu-devel] [RESEND PATCH v3 5/8] pc-dimm: Add pc_dimm_unrealize() for memory hot unplug support.

[zhanghailiang]

On 2014/9/4 21:28, Igor Mammedov wrote:
> On Wed, 27 Aug 2014 16:08:36 +0800
> Tang Chen<address@hidden>  wrote:
>
> > From: Hu Tao<address@hidden>
> >
> > Implement unrealize function for pc-dimm device. It delete subregion from
> s/delete/removes/
>
> > hotplug region, and delete ram address range from guest ram list.
> >
> > Signed-off-by: Hu Tao<address@hidden>
> > Signed-off-by: Tang Chen<address@hidden>
> > ---
> >   hw/mem/pc-dimm.c | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> >
> > diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> > index 20fe0dc..34109a2 100644
> > --- a/hw/mem/pc-dimm.c
> > +++ b/hw/mem/pc-dimm.c
> > @@ -270,12 +270,22 @@ static MemoryRegion 
> > *pc_dimm_get_memory_region(PCDIMMDevice *dimm)
> >       return host_memory_backend_get_memory(dimm->hostmem,&error_abort);
> >   }
> >
> > +static void pc_dimm_unrealize(DeviceState *dev, Error **errp)
> > +{
> > +    PCDIMMDevice *dimm = PC_DIMM(dev);
> > +    MemoryRegion *mr = pc_dimm_get_memory_region(dimm);
> > +
> > +    memory_region_del_subregion(mr->container, mr);
> usually MemoryRegion is treated as opaque and it's fields
> accessed via memory_region_foo() helpers.
>
> > +    vmstate_unregister_ram(mr, dev);
> these 2 lines look like a job for PCMachine which did original mapping/vmstate 
> registration

Actually, this patch also fix the bug *when hotplug memory failing in
the place where after pc_dimm_plug but before the end of device_set_realized,
it does not clear the work done by pc_dimm_plug*.

For there is no callback like pc_dimm_plug_fail_cb for us to call when fail,
Maybe pc_dimm_unrealize is the only place where we can do the clear work...

Thanks,
zhanghailiang

> > +}
> > +
> >   static void pc_dimm_class_init(ObjectClass *oc, void *data)
> >   {
> >       DeviceClass *dc = DEVICE_CLASS(oc);
> >       PCDIMMDeviceClass *ddc = PC_DIMM_CLASS(oc);
> >
> >       dc->realize = pc_dimm_realize;
> > +    dc->unrealize = pc_dimm_unrealize;
> >       dc->props = pc_dimm_properties;
> >
> >       ddc->get_memory_region = pc_dimm_get_memory_region;