iommu: Introduce iommu_request_dm_for_dev()
This function can be called by an IOMMU driver to request
that a device's default domain is direct mapped.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 224c6dd..3b1a255 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1538,3 +1538,56 @@
if (ops && ops->put_dm_regions)
ops->put_dm_regions(dev, list);
}
+
+/* Request that a device is direct mapped by the IOMMU */
+int iommu_request_dm_for_dev(struct device *dev)
+{
+ struct iommu_domain *dm_domain;
+ struct iommu_group *group;
+ int ret;
+
+ /* Device must already be in a group before calling this function */
+ group = iommu_group_get_for_dev(dev);
+ if (!group)
+ return -EINVAL;
+
+ mutex_lock(&group->mutex);
+
+ /* Check if the default domain is already direct mapped */
+ ret = 0;
+ if (group->default_domain &&
+ group->default_domain->type == IOMMU_DOMAIN_IDENTITY)
+ goto out;
+
+ /* Don't change mappings of existing devices */
+ ret = -EBUSY;
+ if (iommu_group_device_count(group) != 1)
+ goto out;
+
+ /* Allocate a direct mapped domain */
+ ret = -ENOMEM;
+ dm_domain = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_IDENTITY);
+ if (!dm_domain)
+ goto out;
+
+ /* Attach the device to the domain */
+ ret = __iommu_attach_group(dm_domain, group);
+ if (ret) {
+ iommu_domain_free(dm_domain);
+ goto out;
+ }
+
+ /* Make the direct mapped domain the default for this group */
+ if (group->default_domain)
+ iommu_domain_free(group->default_domain);
+ group->default_domain = dm_domain;
+
+ pr_info("Using direct mapping for device %s\n", dev_name(dev));
+
+ ret = 0;
+out:
+ mutex_unlock(&group->mutex);
+ iommu_group_put(group);
+
+ return ret;
+}