On Mon, 2015-02-23 at 10:54 -0800, Nishanth Aravamudan wrote:

On 23.02.2015 [13:27:24 +1100], Michael Ellerman wrote:

quoted

On Sat, 2015-21-02 at 19:00:50 UTC, Nishanth Aravamudan wrote:

quoted

On 20.02.2015 [15:31:29 +1100], Michael Ellerman wrote:

quoted

On Thu, 2015-02-19 at 10:41 -0800, Nishanth Aravamudan wrote:

quoted

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.

How does this look? Only compile-tested with CONFIG_IOMMU_API on/off so
far, waiting for access to the test LPAR (should have it on Monday).

Yeah that looks better, thanks.

It probably doesn't build with CONFIG_PCI=n though, but I don't think
CONFIG_PCI=n builds anyway.

Indeed it doesn't. Started looking at CONFIG_PCI=n and immediately hit
the following:

PCI_MSI depends on PCI

PCI can be manually turned off

PSERIES (and a bunch of other platforms) select PCI_MSI

So you end up with PCI_MSI on and PCI off and the build breaks.

Should the platforms depend on PCI_MSI instead?

No, they don't depend on it, they would just like it if PCI is enabled.

That can be fixed fairly easily by making it:

config PSERIES
	select PCI_MSI if PCI


But you then discover that there are ten other places where the build breaks
for PCI=n.

I'm starting to think we should just force PCI on for PSERIES and be done with
it, we could all spend less of our time chasing build breaks for configurations
no one actually cares about in practice (ie. PSERIES=y PCI=n).

cheers