Re: [PATCH 1/5] hw/ppc/spapr_iommu: Register machine reset handler

[Philippe Mathieu-Daudé]

On 4/27/21 3:45 AM, David Gibson wrote:
> On Sat, Apr 24, 2021 at 06:22:25PM +0200, Philippe Mathieu-Daudé wrote:
>> The TYPE_SPAPR_TCE_TABLE device is bus-less, thus isn't reset
>> automatically.  Register a reset handler to get reset with the
>> machine.
>>
>> It doesn't seem to be an issue because it is that way since the
>> device QDev'ifycation 8 years ago, in commit a83000f5e3f
>> ("spapr-tce: make sPAPRTCETable a proper device").
>> Still, correct to have a proper API usage.
> 
> So, the reason this works now is that we explicitly call
> device_reset() on the TCE table from the TCE tables "owner", either a
> PHB (spapr_phb_reset()) or a VIO device (spapr_vio_quiesce_one()).
> 
> I think we want either that, or the register_reset(), not both.

rtas_quiesce() seems to call a DeviceClass::reset() on the
children of TYPE_SPAPR_VIO_BUS:

Abstract TYPE_VIO_SPAPR_DEVICE has the TYPE_SPAPR_VIO_BUS bus_type,
and registers the spapr_vio_busdev_reset() handler, which calls
spapr_vio_quiesce_one()...

So either we already have 2 resets, or the bus is never reset?

The bus is created in spapr_machine_init():

    /* Set up VIO bus */
    spapr->vio_bus = spapr_vio_bus_init();

TYPE_SPAPR_MACHINE class registers spapr_machine_reset(), which
manually calls qemu_devices_reset() and spapr_drc_reset_all(),
but I can't understand if a callee resets vio_bus...