[PATCH v3 03/15] iommu: Always register bus notifiers

Robin Murphy
2022-07-05T17:08:55Z

The number of bus types that the IOMMU subsystem deals with is small and
manageable, so pull that list into core code as a first step towards
cleaning up all the boilerplate bus-awareness from drivers. Calling
iommu_probe_device() before bus->iommu_ops is set will simply return
-ENODEV and not break the notifier call chain, so there should be no
harm in proactively registering all our bus notifiers at init time.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---

v3: Add host1x_context_bus

drivers/iommu/iommu.c | 53 ++++++++++++++++++++++++++-----------------
1 file changed, 32 insertions(+), 21 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 847ad47a2dfd..514edc0eaa94 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -6,6 +6,7 @@

#define pr_fmt(fmt) "iommu: " fmt

+#include <linux/amba/bus.h>
#include <linux/device.h>
#include <linux/dma-iommu.h>
#include <linux/kernel.h>
@@ -16,11 +17,13 @@
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/errno.h>
+#include <linux/host1x_context_bus.h>
#include <linux/iommu.h>
#include <linux/idr.h>
#include <linux/err.h>
#include <linux/pci.h>
#include <linux/bitops.h>
+#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/fsl/mc.h>
#include <linux/module.h>
@@ -75,6 +78,7 @@ static const char * const iommu_group_resv_type_string[] = {
#define IOMMU_CMD_LINE_DMA_API BIT(0)
#define IOMMU_CMD_LINE_STRICT BIT(1)

+static int iommu_bus_init(struct bus_type *bus);
static int iommu_alloc_default_domain(struct iommu_group *group,
struct device *dev);
static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
@@ -103,6 +107,22 @@ struct iommu_group_attribute iommu_group_attr_##_name = \
static LIST_HEAD(iommu_device_list);
static DEFINE_SPINLOCK(iommu_device_lock);

+static struct bus_type * const iommu_buses[] = {
+ &platform_bus_type,
+#ifdef CONFIG_PCI
+ &pci_bus_type,
+#endif
+#ifdef CONFIG_ARM_AMBA
+ &amba_bustype,
+#endif
+#ifdef CONFIG_FSL_MC_BUS
+ &fsl_mc_bus_type,
+#endif
+#ifdef CONFIG_TEGRA_HOST1X_CONTEXT_BUS
+ &host1x_context_device_bus_type,
+#endif
+};
+
/*
* Use a function instead of an array here because the domain-type is a
* bit-field, so an array would waste memory.
@@ -152,6 +172,10 @@ static int __init iommu_subsys_init(void)
(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
"(set via kernel command line)" : "");

+ /* If the system is so broken that this fails, it will WARN anyway */
+ for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++)
+ iommu_bus_init(iommu_buses[i]);
+
return 0;
}
subsys_initcall(iommu_subsys_init);
@@ -1772,35 +1796,19 @@ int bus_iommu_probe(struct bus_type *bus)
return ret;
}

-static int iommu_bus_init(struct bus_type *bus, const struct iommu_ops *ops)
+static int iommu_bus_init(struct bus_type *bus)
{
struct notifier_block *nb;
int err;

- nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
+ nb = kzalloc(sizeof(*nb), GFP_KERNEL);
if (!nb)
return -ENOMEM;

nb->notifier_call = iommu_bus_notifier;
-
err = bus_register_notifier(bus, nb);
if (err)
- goto out_free;
-
- err = bus_iommu_probe(bus);
- if (err)
- goto out_err;
-
-
- return 0;
-
-out_err:
- /* Clean up */
- bus_for_each_dev(bus, NULL, NULL, remove_iommu_group);
- bus_unregister_notifier(bus, nb);
-
-out_free:
- kfree(nb);
+ kfree(nb);

return err;
}
@@ -1833,9 +1841,12 @@ int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
bus->iommu_ops = ops;

/* Do IOMMU specific setup for this bus-type */
- err = iommu_bus_init(bus, ops);
- if (err)
+ 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;
}
--
2.36.1.dirty