Re: [PATCH 00/35] memory: QOM-ify AddressSpace

["Cédric Le Goater" <clg@redhat.com>]

Hello Akihiko,

On 9/17/25 14:56, Akihiko Odaki wrote:
> Based-on: <20250917-subregion-v1-0-bef37d9b4f73@rsg.ci.i.u-tokyo.ac.jp>
> ("[PATCH 00/14] Fix memory region use-after-finalization")
> 
> Make AddressSpaces QOM objects to ensure that they are destroyed when
> their owners are finalized and also to get a unique path for debugging
> output.
> 
> Suggested by BALATON Zoltan:
> https://lore.kernel.org/qemu-devel/cd21698f-db77-eb75-6966-d559fdcab835@eik.bme.hu/
> 
> Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>

I wonder if this is going to fix an issue I was seeing a while ago
in the FSI models. I couldn't find a clean way to avoid corrupting
memory because of how the address_space was created and later on
destroyed. See below,

Thanks,

C.



from hw/fsi/ :
     
     typedef struct OPBus {
         BusState bus;
     
         MemoryRegion mr;
         AddressSpace as;
     } OPBus;
     
     
     typedef struct AspeedAPB2OPBState {
         ...	
         OPBus opb[ASPEED_FSI_NUM];
         ...
     }

     static void fsi_aspeed_apb2opb_realize(DeviceState *dev, Error **errp)
     {
         SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
         AspeedAPB2OPBState *s = ASPEED_APB2OPB(dev);
         int i;
     
         /*
          * TODO: The OPBus model initializes the OPB address space in
          * the .instance_init handler and this is problematic for test
          * device-introspect-test. To avoid a memory corruption and a QEMU
          * crash, qbus_init() should be called from realize(). Something to
          * improve. Possibly, OPBus could also be removed.
          */
         for (i = 0; i < ASPEED_FSI_NUM; i++) {
             qbus_init(&s->opb[i], sizeof(s->opb[i]), TYPE_OP_BUS, DEVICE(s),
                       NULL);
         }
         ....

     static void fsi_opb_init(Object *o)
     {
         OPBus *opb = OP_BUS(o);

         memory_region_init(&opb->mr, 0, TYPE_FSI_OPB, UINT32_MAX);
         address_space_init(&opb->as, &opb->mr, TYPE_FSI_OPB);
    }