powerpc/powernv/pseries: Rework device adding to IOMMU groups

The powernv platform registers IOMMU groups and adds devices to them
from the pci_controller_ops::setup_bridge() hook except one case when
virtual functions (SRIOV VFs) are added from a bus notifier.

The pseries platform registers IOMMU groups from
the pci_controller_ops::dma_bus_setup() hook and adds devices from
the pci_controller_ops::dma_dev_setup() hook. The very same bus notifier
used for powernv does not add devices for pseries though as
__of_scan_bus() adds devices first, then it does the bus/dev DMA setup.

Both platforms use iommu_add_device() which takes a device and expects
it to have a valid IOMMU table struct with an iommu_table_group pointer
which in turn points the iommu_group struct (which represents
an IOMMU group). Although the helper seems easy to use, it relies on
some pre-existing device configuration and associated data structures
which it does not really need.

This simplifies iommu_add_device() to take the table_group pointer
directly. Pseries already has a table_group pointer handy and the bus
notified is not used anyway. For powernv, this copies the existing bus
notifier, makes it work for powernv only which means an easy way of
getting to the table_group pointer. This was tested on VFs but should
also support physical PCI hotplug.

Since iommu_add_device() receives the table_group pointer directly,
pseries does not do TCE cache invalidation (the hypervisor does) nor
allow multiple groups per a VFIO container (in other words sharing
an IOMMU table between partitionable endpoints), this removes
iommu_table_group_link from pseries.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 3 insertions, 55 deletions

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index cbcc6152b7f5..9d5d109f15c0 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -1078,11 +1078,8 @@ void iommu_release_ownership(struct iommu_table *tbl)
 }
 EXPORT_SYMBOL_GPL(iommu_release_ownership);
 
-int iommu_add_device(struct device *dev)
+int iommu_add_device(struct iommu_table_group *table_group, struct device *dev)
 {
-	struct iommu_table *tbl;
-	struct iommu_table_group_link *tgl;
-
 	/*
 	 * The sysfs entries should be populated before
 	 * binding IOMMU group. If sysfs entries isn't
@@ -1098,32 +1095,10 @@ int iommu_add_device(struct device *dev)
 		return -EBUSY;
 	}
 
-	tbl = get_iommu_table_base(dev);
-	if (!tbl) {
-		pr_debug("%s: Skipping device %s with no tbl\n",
-			 __func__, dev_name(dev));
-		return 0;
-	}
-
-	tgl = list_first_entry_or_null(&tbl->it_group_list,
-			struct iommu_table_group_link, next);
-	if (!tgl) {
-		pr_debug("%s: Skipping device %s with no group\n",
-			 __func__, dev_name(dev));
-		return 0;
-	}
 	pr_debug("%s: Adding %s to iommu group %d\n",
-		 __func__, dev_name(dev),
-		 iommu_group_id(tgl->table_group->group));
-
-	if (PAGE_SIZE < IOMMU_PAGE_SIZE(tbl)) {
-		pr_err("%s: Invalid IOMMU page size %lx (%lx) on %s\n",
-		       __func__, IOMMU_PAGE_SIZE(tbl),
-		       PAGE_SIZE, dev_name(dev));
-		return -EINVAL;
-	}
+		 __func__, dev_name(dev),  iommu_group_id(table_group->group));
 
-	return iommu_group_add_device(tgl->table_group->group, dev);
+	return iommu_group_add_device(table_group->group, dev);
 }
 EXPORT_SYMBOL_GPL(iommu_add_device);
 
@@ -1143,31 +1118,4 @@ void iommu_del_device(struct device *dev)
 	iommu_group_remove_device(dev);
 }
 EXPORT_SYMBOL_GPL(iommu_del_device);
-
-static int tce_iommu_bus_notifier(struct notifier_block *nb,
-                unsigned long action, void *data)
-{
-        struct device *dev = data;
-
-        switch (action) {
-        case BUS_NOTIFY_ADD_DEVICE:
-                return iommu_add_device(dev);
-        case BUS_NOTIFY_DEL_DEVICE:
-                if (dev->iommu_group)
-                        iommu_del_device(dev);
-                return 0;
-        default:
-                return 0;
-        }
-}
-
-static struct notifier_block tce_iommu_bus_nb = {
-        .notifier_call = tce_iommu_bus_notifier,
-};
-
-int __init tce_iommu_bus_notifier_init(void)
-{
-        bus_register_notifier(&pci_bus_type, &tce_iommu_bus_nb);
-        return 0;
-}
 #endif /* CONFIG_IOMMU_API */