vio.c:__vio_register_driver && LPAR Migration issue

[Tyrel Datwyler]

On 08/02/2018 11:15 AM, Michael Bringmann wrote:
> Hello:
>     I have been observing an anomaly during LPAR migrations between
> a couple of P8 systems.
> 
> This is the problem.  After migrating an LPAR, the PPC mobility code
> receives RTAS requests to delete nodes with platform-/hardware-specific
> attributes when restarting the kernel after a migration.  My example is
> for migration between a P8 Alpine and a P8 Brazos.  Among the nodes
> that I see being deleted are 'ibm,random-v1', 'ibm,compression-v1',
> 'ibm,platform-facilities', and 'ibm,sym-encryption-v1'.  Of these
> nodes, the following are created during initial boot by calls to
> vio_register_driver:
> 
> drivers/char/hw_random/pseries-rng.c
>         ibm,random-v1
> 
> drivers/crypto/nx/nx-842-pseries.c
>         ibm,compression-v1
> 
> drivers/crypto/nx/nx.c
>         ibm,sym-encryption-v1
> 
> After the migration, these nodes are deleted, but nothing recreates
> them.  If I boot the LPAR on the target system, the nodes are added
> again.
> 
> My question is how do we recreate these nodes after migration?

Hmm, I'd have to see the scenario in action, but these should be added back by ibm,update-nodes RTAS call. There is some debug code in driver/of/dynamic.c that can be enabled that will log node/property dynamic reconfiguration events.

-Tyrel

> 
> Thanks.
>