Commit 71cf1def authored Jan 18, 2013 by Nishanth Aravamudan Committed by Benjamin Herrenschmidt Jan 29, 2013

pseries/iommu: Ensure TCEs are cleared with non-huge DDW

There are now two kinds of DMA windows that might be presented by
PowerVM DDW support -- huge windows (that can map all of system memory
regardless of the LPAR configuration) and non-huge windows (which
can't). They are implemented slightly differently in PowerVM, and thus
have different characteristics. The most obvious is that slot isolate
doesn't clear the TCEs/window for us with non-huge windows. Thus, when a
DLPAR operation occurs on a slot using a non-huge window, TCEs are still
present (the notifier chain doesn't currently remove them explicitly)
and the DLPAR fails. Fix this by calling remove_ddw() first, which will
unmap the DDW TCEs.

Note: a corresponding change to drmgr is needed to actually successfully
DLPAR, such that the device-tree update (which causes the notifier chain
to fire) occurs before slot isolate.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

parent 22b38298

arch/powerpc/platforms/pseries/iommu.c

+1 −10

Original line number	Diff line number	Diff line
		@@ -1296,6 +1296,7 @@ static int iommu_reconfig_notifier(struct notifier_block *nb, unsigned long acti

		switch (action) {
		case OF_RECONFIG_DETACH_NODE:
		remove_ddw(np);
		if (pci && pci->iommu_table)
		iommu_free_table(pci->iommu_table, np->full_name);

		@@ -1308,16 +1309,6 @@ static int iommu_reconfig_notifier(struct notifier_block *nb, unsigned long acti
		}
		}
		spin_unlock(&direct_window_list_lock);

		/*
		* Because the notifier runs after isolation of the
		* slot, we are guaranteed any DMA window has already
		* been revoked and the TCEs have been marked invalid,
		* so we don't need a call to remove_ddw(np). However,
		* if an additional notifier action is added before the
		* isolate call, we should update this code for
		* completeness with such a call.
		*/
		break;
		default:
		err = NOTIFY_DONE;