Re: [PATCH] powerpc/pseries: Only register vio drivers if vio bus exists

[Paul Menzel <pmenzel@molgen.mpg.de>]

Dear Michael,


Am 16.03.21 um 02:09 schrieb Michael Ellerman:
> The vio bus is a fake bus, which we use on pseries LPARs (guests) to
> discover devices provided by the hypervisor. There's no need or sense
> in creating the vio bus on bare metal systems.
> 
> Which is why commit 4336b9337824 ("powerpc/pseries: Make vio and
> ibmebus initcalls pseries specific") made the initialisation of the
> vio bus only happen in LPARs.
> 
> However as a result of that commit we now see errors at boot on bare
> metal systems:
> 
>    Driver 'hvc_console' was unable to register with bus_type 'vio' because the bus was not initialized.
>    Driver 'tpm_ibmvtpm' was unable to register with bus_type 'vio' because the bus was not initialized.
> 
> This happens because those drivers are built-in, and are calling
> vio_register_driver(). It in turn calls driver_register() with a
> reference to vio_bus_type, but we haven't registered vio_bus_type with
> the driver core.
> 
> Fix it by also guarding vio_register_driver() with a check to see if
> we are on pseries.
> 
> Fixes: 4336b9337824 ("powerpc/pseries: Make vio and ibmebus initcalls pseries specific")
> Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
>   arch/powerpc/platforms/pseries/vio.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
> index 9cb4fc839fd5..429053d0402a 100644
> --- a/arch/powerpc/platforms/pseries/vio.c
> +++ b/arch/powerpc/platforms/pseries/vio.c
> @@ -1285,6 +1285,10 @@ static int vio_bus_remove(struct device *dev)
>   int __vio_register_driver(struct vio_driver *viodrv, struct module *owner,
>   			  const char *mod_name)
>   {
> +	// vio_bus_type is only initialised for pseries
> +	if (!machine_is(pseries))
> +		return -ENODEV;
> +
>   	pr_debug("%s: driver %s registering\n", __func__, viodrv->name);
>   
>   	/* fill in 'struct driver' fields */

Thank you. The errors are gone now.

Tested-by: Paul Menzel <pmenzel@molgen.mpg.de> # IBM S822L (POWER8)

As it fixes a commit from Linux 5.8, should it be tagged for the stable 
releases, or is it going to be picked up automatically due to the Fixes tag?


Kind regards,

Paul