[PATCH] pseries/iommu: remove iommu device references via bus notifier

[Michael Ellerman]

On Thu, 2015-02-19 at 10:41 -0800, Nishanth Aravamudan wrote:
> After d905c5df9aef ("PPC: POWERNV: move iommu_add_device earlier"), the
> refcnt on the kobject backing the IOMMU group for a PCI device is
> elevated by each call to pci_dma_dev_setup_pSeriesLP() (via
> set_iommu_table_base_and_group). When we go to dlpar a multi-function
> PCI device out:
> 
> 	iommu_reconfig_notifier ->
> 		iommu_free_table ->
> 			iommu_group_put
> 			BUG_ON(tbl->it_group)
> 
> We trip this BUG_ON, because there are still references on the table, so
> it is not freed. Fix this by also adding a bus notifier identical to
> PowerNV for pSeries.

Please put it somewhere common, arch/powerpc/kernel/iommu.c perhaps, and just
add a second machine_init_call() for pseries.

cheers