Patchwork [4/6] iommu: Add a function to find an iommu group by id

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Submitter Alexey Kardashevskiy
Date May 6, 2013, 7:25 a.m.
Message ID <1367825157-27231-5-git-send-email-aik@ozlabs.ru>
Download mbox | patch
Permalink /patch/241593/
State Superseded
Headers show

Comments

Alexey Kardashevskiy - May 6, 2013, 7:25 a.m.
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.

This adds the iommu_group_get_by_id(id) function which performs
this search.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
 include/linux/iommu.h |    1 +
 2 files changed, 30 insertions(+)

Patch

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ddbdaca..5514dfa 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -204,6 +204,35 @@  again:
 }
 EXPORT_SYMBOL_GPL(iommu_group_alloc);
 
+struct iommu_group *iommu_group_get_by_id(int id)
+{
+	struct kobject *group_kobj;
+	struct iommu_group *group;
+	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;
+
+	group = container_of(group_kobj, struct iommu_group, kobj);
+	BUG_ON(group->id != id);
+
+	kobject_get(group->devices_kobj);
+	kobject_put(&group->kobj);
+
+	return group;
+}
+EXPORT_SYMBOL_GPL(iommu_group_get_by_id);
+
 /**
  * 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..00e5d7d 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_get_by_id(int id);
 extern void iommu_domain_free(struct iommu_domain *domain);
 extern int iommu_attach_device(struct iommu_domain *domain,
 			       struct device *dev);