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authorAlexey Kardashevskiy <aik@ozlabs.ru>2013-03-25 03:23:49 +0400
committerJoerg Roedel <joro@8bytes.org>2013-04-24 21:56:51 +0400
commitaa16bea929aed6ea854b55d2be8306a9fb40e694 (patch)
tree2a2cead5f2b1123b4b4b13d307d6db035e2c13fe /drivers/iommu
parent61e015ac5b4d46c2054a78d9bc82c840274929a0 (diff)
downloadlinux-aa16bea929aed6ea854b55d2be8306a9fb40e694.tar.xz
iommu: Add a function to find an iommu group by id
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_get_by_id(id) function which performs such search. v2: fixed reference counting. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Acked-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Joerg Roedel <joro@8bytes.org>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/iommu.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b972d430d92b..db01af01ce0a 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