[PATCH v3 11/18] iommu: Expose group variants of dma ownership interfaces

Lu Baolu
2021-12-06T02:01:15Z

The vfio needs to set DMA_OWNER_PRIVATE_DOMAIN_USER for the entire group
when attaching it to a vfio container. Expose group variants of setting/
releasing dma ownership for this purpose.

This also exposes the helper iommu_group_dma_owner_unclaimed() for vfio
to report to userspace if the group is viable to user assignment for
compatibility with VFIO_GROUP_FLAGS_VIABLE.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
include/linux/iommu.h | 21 ++++++++++++++++
drivers/iommu/iommu.c | 58 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 79 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 24676b498f38..afcc07bc8d41 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -701,6 +701,10 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle);
int iommu_device_set_dma_owner(struct device *dev, enum iommu_dma_owner owner,
void *owner_cookie);
void iommu_device_release_dma_owner(struct device *dev, enum iommu_dma_owner owner);
+int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
+ void *owner_cookie);
+void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner);
+bool iommu_group_dma_owner_unclaimed(struct iommu_group *group);

#else /* CONFIG_IOMMU_API */

@@ -1117,6 +1121,23 @@ static inline void iommu_device_release_dma_owner(struct device *dev,
enum iommu_dma_owner owner)
{
}
+
+static inline int iommu_group_set_dma_owner(struct iommu_group *group,
+ enum iommu_dma_owner owner,
+ void *owner_cookie)
+{
+ return -EINVAL;
+}
+
+static inline void iommu_group_release_dma_owner(struct iommu_group *group,
+ enum iommu_dma_owner owner)
+{
+}
+
+static inline bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
+{
+ return false;
+}
#endif /* CONFIG_IOMMU_API */

/**
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 0cba04a8ea3b..423197db99a9 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3425,6 +3425,64 @@ static void __iommu_group_release_dma_owner(struct iommu_group *group,
}
}

+/**
+ * iommu_group_set_dma_owner() - Set DMA ownership of a group
+ * @group: The group.
+ * @owner: DMA owner type.
+ * @owner_cookie: Caller specified pointer. Could be used for exclusive
+ * declaration. Could be NULL.
+ *
+ * This is to support backward compatibility for legacy vfio which manages
+ * dma ownership in group level. New invocations on this interface should be
+ * prohibited. Instead, please turn to iommu_device_set_dma_owner().
+ */
+int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
+ void *owner_cookie)
+{
+ int ret;
+
+ mutex_lock(&group->mutex);
+ ret = __iommu_group_set_dma_owner(group, owner, owner_cookie);
+ mutex_unlock(&group->mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_group_set_dma_owner);
+
+/**
+ * iommu_group_release_dma_owner() - Release DMA ownership of a group
+ * @group: The group.
+ * @owner: DMA owner type.
+ *
+ * Release the DMA ownership claimed by iommu_group_set_dma_owner().
+ */
+void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner)
+{
+ mutex_lock(&group->mutex);
+ __iommu_group_release_dma_owner(group, owner);
+ mutex_unlock(&group->mutex);
+}
+EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner);
+
+/**
+ * iommu_group_dma_owner_unclaimed() - Is group dma ownership claimed
+ * @group: The group.
+ *
+ * This provides status check on a given group. It is racey and only for
+ * non-binding status reporting.
+ */
+bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
+{
+ enum iommu_dma_owner owner;
+
+ mutex_lock(&group->mutex);
+ owner = group->dma_owner;
+ mutex_unlock(&group->mutex);
+
+ return owner == DMA_OWNER_NONE;
+}
+EXPORT_SYMBOL_GPL(iommu_group_dma_owner_unclaimed);
+
/**
* iommu_device_set_dma_owner() - Set DMA ownership of a device
* @dev: The device.
--
2.25.1