[PATCH] iommu: add a function to find an iommu group by id

[PATCH] iommu: add a function to find an iommu group by id

[Alexey Kardashevskiy]

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 <aik@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

Re: [PATCH] iommu: add a function to find an iommu group by id

[Alex Williamson]

On Thu, 2013-03-21 at 18:48 +1100, Alexey Kardashevskiy wrote:
> 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 <aik@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);

Don't you need to do some reference counting here?  Otherwise there's no
guarantee the returned pointer is still valid by the time it's used.
The interface should probably be iommu_group_get_by_id().  Thanks,

Alex

> +
>  /**
>   * 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);

Re: [PATCH] iommu: add a function to find an iommu group by id

[Alex Williamson]

On Thu, 2013-03-21 at 18:48 +1100, Alexey Kardashevskiy wrote:
> 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 <aik-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>
> ---
>  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);

Don't you need to do some reference counting here?  Otherwise there's no
guarantee the returned pointer is still valid by the time it's used.
The interface should probably be iommu_group_get_by_id().  Thanks,

Alex

> +
>  /**
>   * 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);

[PATCH] iommu: add a function to find an iommu group by id

[Alexey Kardashevskiy]

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.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 drivers/iommu/iommu.c |   28 ++++++++++++++++++++++++++++
 include/linux/iommu.h |    1 +
 2 files changed, 29 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1065a1a..531cbb5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -204,6 +204,34 @@ again:
 }
 EXPORT_SYMBOL_GPL(iommu_group_alloc);
 
+struct iommu_group *iommu_group_get_by_id(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);
+
+	kobject_get(grp->devices_kobj);
+
+	return grp;
+}
+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);
-- 
1.7.10.4

[PATCH] iommu: add a function to find an iommu group by id

[Alexey Kardashevskiy]

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.

Signed-off-by: Alexey Kardashevskiy <aik-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>
---
 drivers/iommu/iommu.c |   28 ++++++++++++++++++++++++++++
 include/linux/iommu.h |    1 +
 2 files changed, 29 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1065a1a..531cbb5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -204,6 +204,34 @@ again:
 }
 EXPORT_SYMBOL_GPL(iommu_group_alloc);
 
+struct iommu_group *iommu_group_get_by_id(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);
+
+	kobject_get(grp->devices_kobj);
+
+	return grp;
+}
+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);
-- 
1.7.10.4

Re: [PATCH] iommu: add a function to find an iommu group by id

[Alex Williamson]

On Fri, 2013-03-22 at 17:49 +1100, Alexey Kardashevskiy wrote:
> 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.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---

v2: <describe what changed>

>  drivers/iommu/iommu.c |   28 ++++++++++++++++++++++++++++
>  include/linux/iommu.h |    1 +
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1065a1a..531cbb5 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -204,6 +204,34 @@ again:
>  }
>  EXPORT_SYMBOL_GPL(iommu_group_alloc);
>  
> +struct iommu_group *iommu_group_get_by_id(int id)
> +{
> +	struct kobject *group_kobj;
> +	struct iommu_group *grp;

This is named "group" everywhere else in this file.

> +	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);

This does a kobject_get on group->kobj

> +	kfree(name);
> +
> +	if (!group_kobj)
> +		return NULL;
> +
> +	grp = container_of(group_kobj, struct iommu_group, kobj);
> +	BUG_ON(grp->id != id);
> +

Here you want to exchange one reference for another, so first do the
get:

> +	kobject_get(grp->devices_kobj);

Now you need to release the get from the find:

kobject_put(&group->kobj)

> +
> +	return grp;
> +}
> +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);

Re: [PATCH] iommu: add a function to find an iommu group by id

[Alex Williamson]

On Fri, 2013-03-22 at 17:49 +1100, Alexey Kardashevskiy wrote:
> 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.
> 
> Signed-off-by: Alexey Kardashevskiy <aik-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>
> ---

v2: <describe what changed>

>  drivers/iommu/iommu.c |   28 ++++++++++++++++++++++++++++
>  include/linux/iommu.h |    1 +
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1065a1a..531cbb5 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -204,6 +204,34 @@ again:
>  }
>  EXPORT_SYMBOL_GPL(iommu_group_alloc);
>  
> +struct iommu_group *iommu_group_get_by_id(int id)
> +{
> +	struct kobject *group_kobj;
> +	struct iommu_group *grp;

This is named "group" everywhere else in this file.

> +	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);

This does a kobject_get on group->kobj

> +	kfree(name);
> +
> +	if (!group_kobj)
> +		return NULL;
> +
> +	grp = container_of(group_kobj, struct iommu_group, kobj);
> +	BUG_ON(grp->id != id);
> +

Here you want to exchange one reference for another, so first do the
get:

> +	kobject_get(grp->devices_kobj);

Now you need to release the get from the find:

kobject_put(&group->kobj)

> +
> +	return grp;
> +}
> +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);

Re: [PATCH] iommu: add a function to find an iommu group by id

[Joerg Roedel]

On Mon, Mar 25, 2013 at 10:23:49AM +1100, Alexey Kardashevskiy wrote:
> 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>

Applied to core branch, thanks Alexey.

Re: [PATCH] iommu: add a function to find an iommu group by id

[Joerg Roedel]

On Mon, Mar 25, 2013 at 10:23:49AM +1100, Alexey Kardashevskiy wrote:
> 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-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>

Applied to core branch, thanks Alexey.

Re: [PATCH] iommu: add a function to find an iommu group by id

[Don Dutile]

On 03/25/2013 10:28 AM, Alex Williamson wrote:
> On Mon, 2013-03-25 at 10:23 +1100, Alexey Kardashevskiy wrote:
>> 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.
>
> Subject: [PATCH v3]....
>
> v2 was the last one, where's the changelog for v3?
>> v2: fixed reference counting.
>>
and changed function name...

>> Signed-off-by: Alexey Kardashevskiy<aik@ozlabs.ru>
>> ---
>
> Acked-by: Alex Williamson<alex.williamson@redhat.com>
>
>>   drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
>>   include/linux/iommu.h |    1 +
>>   2 files changed, 30 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 1065a1a..0de83eb 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);
>
>
>
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [PATCH] iommu: add a function to find an iommu group by id

[Don Dutile]

On 03/25/2013 10:28 AM, Alex Williamson wrote:
> On Mon, 2013-03-25 at 10:23 +1100, Alexey Kardashevskiy wrote:
>> 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.
>
> Subject: [PATCH v3]....
>
> v2 was the last one, where's the changelog for v3?
>> v2: fixed reference counting.
>>
and changed function name...

>> Signed-off-by: Alexey Kardashevskiy<aik-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>
>> ---
>
> Acked-by: Alex Williamson<alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>
>>   drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
>>   include/linux/iommu.h |    1 +
>>   2 files changed, 30 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 1065a1a..0de83eb 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);
>
>
>
> _______________________________________________
> iommu mailing list
> iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [PATCH] iommu: add a function to find an iommu group by id

[Alex Williamson]

On Mon, 2013-03-25 at 10:23 +1100, Alexey Kardashevskiy wrote:
> 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.

Subject: [PATCH v3]....

v2 was the last one, where's the changelog for v3?
> v2: fixed reference counting.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---

Acked-by: Alex Williamson <alex.williamson@redhat.com>

>  drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
>  include/linux/iommu.h |    1 +
>  2 files changed, 30 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1065a1a..0de83eb 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);

Re: [PATCH] iommu: add a function to find an iommu group by id

[Alex Williamson]

On Mon, 2013-03-25 at 10:23 +1100, Alexey Kardashevskiy wrote:
> 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.

Subject: [PATCH v3]....

v2 was the last one, where's the changelog for v3?
> v2: fixed reference counting.
> 
> Signed-off-by: Alexey Kardashevskiy <aik-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>
> ---

Acked-by: Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

>  drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
>  include/linux/iommu.h |    1 +
>  2 files changed, 30 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1065a1a..0de83eb 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);

[PATCH] iommu: add a function to find an iommu group by id

[Alexey Kardashevskiy]

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>
---
 drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
 include/linux/iommu.h |    1 +
 2 files changed, 30 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1065a1a..0de83eb 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);
-- 
1.7.10.4

[PATCH] iommu: add a function to find an iommu group by id

[Alexey Kardashevskiy]

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-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>
---
 drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
 include/linux/iommu.h |    1 +
 2 files changed, 30 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1065a1a..0de83eb 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);
-- 
1.7.10.4