[PATCH 1/2] iommu/fsl: Do not use iommu_group_remove_device() under ops->device_group()

[Jason Gunthorpe <jgg@nvidia.com>]

This API is expected to be used only by POWER and VFIO no-iommu that
manually manage the group lifecycle. It should not be called under
ops->device_group().

This is already buggy as is since the core code does not expect a probed
driver to loose it's iommu_group without also releasing the device.

FSL seems to be trying to block the platform_device that represents the
pci_controller, eg the thing passed to fsl_add_bridge(), from having an
iommu_group.

Instead of creating an iommu_group that we don't want and then later
removing it, just don't create it at all in the first place.

For the 'pci_endpt_partitioning' case every PCI device already gets its
own iommu_group through the standard code, so it is unclear why having a
dedicated group for the controller could be problematic.

For the other case, the controller group was being used to bizarrely
de-duplicate the group in it's hose. Instead just directly create a group
for the hose the first time we encounter it. The code already searches the
entire hose to find any iommu_group. Again, it is unclear why having the
pci_controller inside the same iommu_group as the PCI devices would be
harmful.

In any case, this is a cleaner way to not enable iommu support for the
platform_device.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/fsl_pamu_domain.c | 42 ++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c
index bce37229709965..bf045f58cd50ae 100644
--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c
@@ -11,6 +11,7 @@
 
 #include <linux/platform_device.h>
 #include <sysdev/fsl_pci.h>
+#include <linux/pci.h>
 
 /*
  * Global spinlock that needs to be held while
@@ -379,7 +380,21 @@ static struct iommu_group *get_shared_pci_device_group(struct pci_dev *pdev)
 		bus = bus->parent;
 	}
 
-	return NULL;
+	return iommu_group_alloc();
+}
+
+static int __is_pci_controller_parent(struct device *dev, void *data)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pci_controller *pci_ctl = pci_bus_to_host(pdev->bus);
+
+	return dev == pci_ctl->parent;
+}
+
+static bool is_pci_controller_parent(struct device *dev)
+{
+	return bus_for_each_dev(&pci_bus_type, NULL, NULL,
+				__is_pci_controller_parent);
 }
 
 static struct iommu_group *get_pci_device_group(struct pci_dev *pdev)
@@ -393,30 +408,12 @@ static struct iommu_group *get_pci_device_group(struct pci_dev *pdev)
 	/* We can partition PCIe devices so assign device group to the device */
 	if (pci_endpt_partitioning) {
 		group = pci_device_group(&pdev->dev);
-
-		/*
-		 * PCIe controller is not a paritionable entity
-		 * free the controller device iommu_group.
-		 */
-		if (pci_ctl->parent->iommu_group)
-			iommu_group_remove_device(pci_ctl->parent);
 	} else {
 		/*
 		 * All devices connected to the controller will share the
-		 * PCI controllers device group. If this is the first
-		 * device to be probed for the pci controller, copy the
-		 * device group information from the PCI controller device
-		 * node and remove the PCI controller iommu group.
-		 * For subsequent devices, the iommu group information can
-		 * be obtained from sibling devices (i.e. from the bus_devices
-		 * link list).
+		 * same device group.
 		 */
-		if (pci_ctl->parent->iommu_group) {
-			group = get_device_iommu_group(pci_ctl->parent);
-			iommu_group_remove_device(pci_ctl->parent);
-		} else {
-			group = get_shared_pci_device_group(pdev);
-		}
+		group = get_shared_pci_device_group(pdev);
 	}
 
 	if (!group)
@@ -436,7 +433,8 @@ static struct iommu_group *fsl_pamu_device_group(struct device *dev)
 	 */
 	if (dev_is_pci(dev))
 		group = get_pci_device_group(to_pci_dev(dev));
-	else if (of_get_property(dev->of_node, "fsl,liodn", &len))
+	else if (of_get_property(dev->of_node, "fsl,liodn", &len) &&
+		 !is_pci_controller_parent(dev))
 		group = get_device_iommu_group(dev);
 
 	return group;
-- 
2.40.1