Re: [PATCH for-6.0 4/4] hw/ppc/e500plat: Only try to add valid dynamic sysbus devices to platform bus

[David Gibson]

On Thu, Mar 25, 2021 at 03:33:10PM +0000, Peter Maydell wrote:
> The e500plat machine device plug callback currently calls
> platform_bus_link_device() for any sysbus device.  This is overly
> broad, because platform_bus_link_device() will unconditionally grab
> the IRQs and MMIOs of the device it is passed, whether it was
> intended for the platform bus or not.  Restrict hotpluggability of
> sysbus devices to only those devices on the dynamic sysbus whitelist.
> 
> We were mostly getting away with this because the board creates the
> platform bus as the last device it creates, and so the hotplug
> callback did not do anything for all the sysbus devices created by
> the board itself.  However if the user plugged in a device which
> itself uses a sysbus device internally we would have mishandled this
> and probably asserted. An example of this is:
>  qemu-system-ppc64 -M ppce500 -device macio-oldworld
> 
> This isn't a sensible command because the macio-oldworld device
> is really specific to the 'g3beige' machine, but we now fail
> with a reasonable error message rather than asserting:
> qemu-system-ppc64: Device heathrow is not supported by this machine yet.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Acked-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/ppc/e500plat.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc/e500plat.c b/hw/ppc/e500plat.c
> index bddd5e7c48f..fc911bbb7bd 100644
> --- a/hw/ppc/e500plat.c
> +++ b/hw/ppc/e500plat.c
> @@ -48,7 +48,9 @@ static void e500plat_machine_device_plug_cb(HotplugHandler 
> *hotplug_dev,
>      PPCE500MachineState *pms = PPCE500_MACHINE(hotplug_dev);
>  
>      if (pms->pbus_dev) {
> -        if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +        MachineClass *mc = MACHINE_GET_CLASS(pms);
> +
> +        if (device_is_dynamic_sysbus(mc, dev)) {
>              platform_bus_link_device(pms->pbus_dev, SYS_BUS_DEVICE(dev));
>          }
>      }
> @@ -58,7 +60,9 @@ static
>  HotplugHandler *e500plat_machine_get_hotpug_handler(MachineState *machine,
>                                                      DeviceState *dev)
>  {
> -    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +    MachineClass *mc = MACHINE_GET_CLASS(machine);
> +
> +    if (device_is_dynamic_sysbus(mc, dev)) {
>          return HOTPLUG_HANDLER(machine);
>      }
>  

-- 
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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