[PATCH v4 05/16] iommu: Move bus setup to IOMMU device registration
From: Robin Murphy <robin.murphy@arm.com>
Date: 2022-08-15 16:20:52
Also in:
linux-iommu, lkml
Subsystem:
iommu subsystem, the rest · Maintainers:
Joerg Roedel, Will Deacon, Linus Torvalds
Move the bus setup to iommu_device_register(). This should allow bus_iommu_probe() to be correctly replayed for multiple IOMMU instances, and leaves bus_set_iommu() as a glorified no-op to be cleaned up next. At this point we can also handle cleanup better than just rolling back the most-recently-touched bus upon failure - which may release devices owned by other already-registered instances, and still leave devices on other buses with dangling pointers to the failed instance. Now it's easy to clean up the exact footprint of a given instance, no more, no less. Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-By: Krishna Reddy <vdumpa@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Tested-by: Matthew Rosato <mjrosato@linux.ibm.com> # s390 Tested-by: Niklas Schnelle <schnelle@linux.ibm.com> # s390 Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- v4: Factor out the ops check in iommu_device_register() to keep the loop even simpler, and comment the nominal change in behaviour drivers/iommu/iommu.c | 55 +++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 25 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index a8d14f2a1035..4db0874a5ed6 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c@@ -188,6 +188,14 @@ static int __init iommu_subsys_init(void) } subsys_initcall(iommu_subsys_init); +static int remove_iommu_group(struct device *dev, void *data) +{ + if (dev->iommu && dev->iommu->iommu_dev == data) + iommu_release_device(dev); + + return 0; +} + /** * iommu_device_register() - Register an IOMMU hardware instance * @iommu: IOMMU handle for the instance
@@ -199,9 +207,18 @@ subsys_initcall(iommu_subsys_init); int iommu_device_register(struct iommu_device *iommu, const struct iommu_ops *ops, struct device *hwdev) { + int err = 0; + /* We need to be able to take module references appropriately */ if (WARN_ON(is_module_address((unsigned long)ops) && !ops->owner)) return -EINVAL; + /* + * Temporarily enforce global restriction to a single driver. This was + * already the de-facto behaviour, since any possible combination of + * existing drivers would compete for at least the PCI or platform bus. + */ + if (iommu_buses[0]->iommu_ops && iommu_buses[0]->iommu_ops != ops) + return -EBUSY; iommu->ops = ops; if (hwdev)
@@ -210,12 +227,22 @@ int iommu_device_register(struct iommu_device *iommu, spin_lock(&iommu_device_lock); list_add_tail(&iommu->list, &iommu_device_list); spin_unlock(&iommu_device_lock); - return 0; + + for (int i = 0; i < ARRAY_SIZE(iommu_buses) && !err; i++) { + iommu_buses[i]->iommu_ops = ops; + err = bus_iommu_probe(iommu_buses[i]); + } + if (err) + iommu_device_unregister(iommu); + return err; } EXPORT_SYMBOL_GPL(iommu_device_register); void iommu_device_unregister(struct iommu_device *iommu) { + for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) + bus_for_each_dev(iommu_buses[i], NULL, iommu, remove_iommu_group); + spin_lock(&iommu_device_lock); list_del(&iommu->list); spin_unlock(&iommu_device_lock);
@@ -1644,13 +1671,6 @@ static int probe_iommu_group(struct device *dev, void *data) return ret; } -static int remove_iommu_group(struct device *dev, void *data) -{ - iommu_release_device(dev); - - return 0; -} - static int iommu_bus_notifier(struct notifier_block *nb, unsigned long action, void *data) {
@@ -1822,27 +1842,12 @@ int bus_iommu_probe(struct bus_type *bus) */ int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops) { - int err; - - if (ops == NULL) { - bus->iommu_ops = NULL; - return 0; - } - - if (bus->iommu_ops != NULL) + if (bus->iommu_ops && ops && bus->iommu_ops != ops) return -EBUSY; bus->iommu_ops = ops; - /* Do IOMMU specific setup for this bus-type */ - err = bus_iommu_probe(bus); - if (err) { - /* Clean up */ - bus_for_each_dev(bus, NULL, NULL, remove_iommu_group); - bus->iommu_ops = NULL; - } - - return err; + return 0; } EXPORT_SYMBOL_GPL(bus_set_iommu);
--
2.36.1.dirty
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