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>
(cherry picked from commit d290f1e70d85a9a4d124594c6a3d769329960bdc)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 13bdd49f5334022c2426e430d5d6dc8fdb73a5ff..e025b5a8b42d2b6c313058bbc7c60990fc07399a 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1538,3 +1538,56 @@ void iommu_put_dm_regions(struct device *dev, struct list_head *list)
        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;
+}

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index b944b2be4fa26ef663ec31291926ac38973ab318..dc767f7c3704639da944153e8bdae7cf40cd804d 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -225,6 +225,7 @@ extern void iommu_set_fault_handler(struct iommu_domain *domain,
 
 extern void iommu_get_dm_regions(struct device *dev, struct list_head *list);
 extern void iommu_put_dm_regions(struct device *dev, struct list_head *list);
+extern int iommu_request_dm_for_dev(struct device *dev);
 
 extern int iommu_attach_group(struct iommu_domain *domain,
                              struct iommu_group *group);
@@ -411,6 +412,11 @@ static inline void iommu_put_dm_regions(struct device *dev,
 {
 }
 
+static inline int iommu_request_dm_for_dev(struct device *dev)
+{
+       return -ENODEV;
+}
+
 static inline int iommu_attach_group(struct iommu_domain *domain,
                                     struct iommu_group *group)
 {