Don't treat all sysbus devices as hotpluggable

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

Posted by Peter Maydell 4 years, 10 months ago

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>
---
 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);
     }
 
-- 
2.20.1

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

Posted by David Gibson 4 years, 10 months ago

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

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

Posted by Auger Eric 4 years, 10 months ago


On 3/25/21 4:33 PM, 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>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> ---
>  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);
>      }
>  
>

[PATCH for-6.0 1/4] include/hw/boards.h: Document machine_class_allow_dynamic_sysbus_dev()
[PATCH for-6.0 2/4] machine: Provide a function to check the dynamic sysbus whitelist
[PATCH for-6.0 3/4] hw/arm/virt: Only try to add valid dynamic sysbus devices to platform bus
[PATCH for-6.0 4/4] hw/ppc/e500plat: Only try to add valid dynamic sysbus devices to platform bus