As IOMMU groups are exposed to the user space by their numbers,
the user space can use them in various kernel APIs so the kernel
might need an API to find a group by its ID.
As an example, QEMU VFIO on PPC64 platform needs it to associate
a logical bus number (LIOBN) with a specific IOMMU group in order
to support in-kernel handling of DMA map/unmap requests.
The patch adds the iommu_group_find(id) function which performs
such search.
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
drivers/iommu/iommu.c | 26 ++++++++++++++++++++++++++
include/linux/iommu.h | 1 +
2 files changed, 27 insertions(+)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b0afd3d..6340cac 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -205,6 +205,32 @@ printk("%s %u grp %d\n", __func__, __LINE__,
iommu_group_id(group));
}
EXPORT_SYMBOL_GPL(iommu_group_alloc);
+struct iommu_group *iommu_group_find(int id)
+{
+ struct kobject *group_kobj;
+ struct iommu_group *grp;
+ const char *name;
+
+ if (!iommu_group_kset)
+ return NULL;
+
+ name = kasprintf(GFP_KERNEL, "%d", id);
+ if (!name)
+ return NULL;
+
+ group_kobj = kset_find_obj(iommu_group_kset, name);
+ kfree(name);
+
+ if (!group_kobj)
+ return NULL;
+
+ grp = container_of(group_kobj, struct iommu_group, kobj);
+ BUG_ON(grp->id != id);
+
+ return grp;
+}
+EXPORT_SYMBOL_GPL(iommu_group_find);
+
/**
* iommu_group_get_iommudata - retrieve iommu_data registered for a group
* @group: the group
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index f3b99e1..20281d5 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -113,6 +113,7 @@ struct iommu_ops {
extern int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops);
extern bool iommu_present(struct bus_type *bus);
extern struct iommu_domain *iommu_domain_alloc(struct bus_type *bus);
+extern struct iommu_group *iommu_group_find(int id);
extern void iommu_domain_free(struct iommu_domain *domain);
extern int iommu_attach_device(struct iommu_domain *domain,
struct device *dev);
--
1.7.10.4
--
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