[PATCH v3 2/4] iommu: Add iommu_aux_at(de)tach_group()

Lu Baolu
2020-07-14T06:02:01Z

This adds two new aux-domain APIs for a use case like vfio/mdev where
sub-devices derived from an aux-domain capable device are created and
put in an iommu_group.

/**
* iommu_aux_attach_group - attach an aux-domain to an iommu_group which
* contains sub-devices (for example mdevs) derived
* from @dev.
* @domain: an aux-domain;
* @group: an iommu_group which contains sub-devices derived from @dev;
* @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
*
* Returns 0 on success, or an error value.
*/
int iommu_aux_attach_group(struct iommu_domain *domain,
struct iommu_group *group,
struct device *dev)

/**
* iommu_aux_detach_group - detach an aux-domain from an iommu_group
*
* @domain: an aux-domain;
* @group: an iommu_group which contains sub-devices derived from @dev;
* @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
*
* @domain must have been attached to @group via iommu_aux_attach_group().
*/
void iommu_aux_detach_group(struct iommu_domain *domain,
struct iommu_group *group,
struct device *dev)

It also adds a flag in the iommu_group data structure to identify
an iommu_group with aux-domain attached from those normal ones.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/iommu.c | 58 +++++++++++++++++++++++++++++++++++++++++++
include/linux/iommu.h | 17 +++++++++++++
2 files changed, 75 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index e1fdd3531d65..cad5a19ebf22 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -45,6 +45,7 @@ struct iommu_group {
struct iommu_domain *default_domain;
struct iommu_domain *domain;
struct list_head entry;
+ unsigned int aux_domain_attached:1;
};

struct group_device {
@@ -2759,6 +2760,63 @@ int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
}
EXPORT_SYMBOL_GPL(iommu_aux_get_pasid);

+/**
+ * iommu_aux_attach_group - attach an aux-domain to an iommu_group which
+ * contains sub-devices (for example mdevs) derived
+ * from @dev.
+ * @domain: an aux-domain;
+ * @group: an iommu_group which contains sub-devices derived from @dev;
+ * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
+ *
+ * Returns 0 on success, or an error value.
+ */
+int iommu_aux_attach_group(struct iommu_domain *domain,
+ struct iommu_group *group, struct device *dev)
+{
+ int ret = -EBUSY;
+
+ mutex_lock(&group->mutex);
+ if (group->domain)
+ goto out_unlock;
+
+ ret = iommu_aux_attach_device(domain, dev);
+ if (!ret) {
+ group->domain = domain;
+ group->aux_domain_attached = true;
+ }
+
+out_unlock:
+ mutex_unlock(&group->mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_aux_attach_group);
+
+/**
+ * iommu_aux_detach_group - detach an aux-domain from an iommu_group
+ *
+ * @domain: an aux-domain;
+ * @group: an iommu_group which contains sub-devices derived from @dev;
+ * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
+ *
+ * @domain must have been attached to @group via iommu_aux_attach_group().
+ */
+void iommu_aux_detach_group(struct iommu_domain *domain,
+ struct iommu_group *group, struct device *dev)
+{
+ mutex_lock(&group->mutex);
+
+ if (WARN_ON(!group->aux_domain_attached || group->domain != domain))
+ goto out_unlock;
+
+ iommu_aux_detach_device(domain, dev);
+ group->aux_domain_attached = false;
+ group->domain = NULL;
+
+out_unlock:
+ mutex_unlock(&group->mutex);
+}
+EXPORT_SYMBOL_GPL(iommu_aux_detach_group);
+
/**
* iommu_sva_bind_device() - Bind a process address space to a device
* @dev: the device
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5657d4fef9f2..9506551139ab 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -635,6 +635,10 @@ bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features f);
int iommu_aux_attach_device(struct iommu_domain *domain, struct device *dev);
void iommu_aux_detach_device(struct iommu_domain *domain, struct device *dev);
int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev);
+int iommu_aux_attach_group(struct iommu_domain *domain,
+ struct iommu_group *group, struct device *dev);
+void iommu_aux_detach_group(struct iommu_domain *domain,
+ struct iommu_group *group, struct device *dev);

struct iommu_sva *iommu_sva_bind_device(struct device *dev,
struct mm_struct *mm,
@@ -1023,6 +1027,19 @@ iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
return -ENODEV;
}

+static inline int
+iommu_aux_attach_group(struct iommu_domain *domain,
+ struct iommu_group *group, struct device *dev)
+{
+ return -ENODEV;
+}
+
+static inline void
+iommu_aux_detach_group(struct iommu_domain *domain,
+ struct iommu_group *group, struct device *dev)
+{
+}
+
static inline struct iommu_sva *
iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
{
--
2.17.1