iommu: Cleanup iommu_change_dev_def_domain()

As the singleton group limitation has been removed, cleanup the code
in iommu_change_dev_def_domain() accordingly.

Documentation is also updated.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230322064956.263419-7-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/Documentation/ABI/testing/sysfs-kernel-iommu_groups b/Documentation/ABI/testing/sysfs-kernel-iommu_groups
index b15af6a5bc08145206553a5faa5270ed586773c2..a42d4383d99939253bf01840c6393f81c87aab17 100644 (file)
--- a/Documentation/ABI/testing/sysfs-kernel-iommu_groups
+++ b/Documentation/ABI/testing/sysfs-kernel-iommu_groups
@@ -53,7 +53,6 @@ Description:  /sys/kernel/iommu_groups/<grp_id>/type shows the type of default
 
                The default domain type of a group may be modified only when
 
-               - The group has only one device.
                - The device in the group is not bound to any device driver.
                  So, the users must unbind the appropriate driver before
                  changing the default domain type.

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6538c72b5ae15f64a85aee53588f7f2592c2bc70..9fccfc69e4c5c954e5650d819b93c3f1db856a54 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2867,11 +2867,10 @@ int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
 
 /*
- * Changes the default domain of an iommu group that has *only* one device
+ * Changes the default domain of an iommu group
  *
  * @group: The group for which the default domain should be changed
- * @prev_dev: The device in the group (this is used to make sure that the device
- *      hasn't changed after the caller has called this function)
+ * @dev: The first device in the group
  * @type: The type of the new default domain that gets associated with the group
  *
  * Returns 0 on success and error code on failure
@@ -2882,103 +2881,63 @@ EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
  *    Please take a closer look if intended to use for other purposes.
  */
 static int iommu_change_dev_def_domain(struct iommu_group *group,
-                                      struct device *prev_dev, int type)
+                                      struct device *dev, int type)
 {
+       struct __group_domain_type gtype = {NULL, 0};
        struct iommu_domain *prev_dom;
-       struct group_device *grp_dev;
-       int ret, dev_def_dom;
-       struct device *dev;
+       int ret;
 
        lockdep_assert_held(&group->mutex);
 
-       if (group->default_domain != group->domain) {
-               dev_err_ratelimited(prev_dev, "Group not assigned to default domain\n");
-               ret = -EBUSY;
-               goto out;
-       }
-
-       /*
-        * iommu group wasn't locked while acquiring device lock in
-        * iommu_group_store_type(). So, make sure that the device count hasn't
-        * changed while acquiring device lock.
-        *
-        * Changing default domain of an iommu group with two or more devices
-        * isn't supported because there could be a potential deadlock. Consider
-        * the following scenario. T1 is trying to acquire device locks of all
-        * the devices in the group and before it could acquire all of them,
-        * there could be another thread T2 (from different sub-system and use
-        * case) that has already acquired some of the device locks and might be
-        * waiting for T1 to release other device locks.
-        */
-       if (iommu_group_device_count(group) != 1) {
-               dev_err_ratelimited(prev_dev, "Cannot change default domain: Group has more than one device\n");
-               ret = -EINVAL;
-               goto out;
-       }
-
-       /* Since group has only one device */
-       grp_dev = list_first_entry(&group->devices, struct group_device, list);
-       dev = grp_dev->dev;
-
-       if (prev_dev != dev) {
-               dev_err_ratelimited(prev_dev, "Cannot change default domain: Device has been changed\n");
-               ret = -EBUSY;
-               goto out;
-       }
-
        prev_dom = group->default_domain;
-       if (!prev_dom) {
-               ret = -EINVAL;
-               goto out;
-       }
-
-       dev_def_dom = iommu_get_def_domain_type(dev);
+       __iommu_group_for_each_dev(group, &gtype,
+                                  probe_get_default_domain_type);
        if (!type) {
                /*
                 * If the user hasn't requested any specific type of domain and
                 * if the device supports both the domains, then default to the
                 * domain the device was booted with
                 */
-               type = dev_def_dom ? : iommu_def_domain_type;
-       } else if (dev_def_dom && type != dev_def_dom) {
-               dev_err_ratelimited(prev_dev, "Device cannot be in %s domain\n",
+               type = gtype.type ? : iommu_def_domain_type;
+       } else if (gtype.type && type != gtype.type) {
+               dev_err_ratelimited(dev, "Device cannot be in %s domain\n",
                                    iommu_domain_type_str(type));
-               ret = -EINVAL;
-               goto out;
+               return -EINVAL;
        }
 
        /*
         * Switch to a new domain only if the requested domain type is different
         * from the existing default domain type
         */
-       if (prev_dom->type == type) {
-               ret = 0;
-               goto out;
-       }
+       if (prev_dom->type == type)
+               return 0;
+
+       group->default_domain = NULL;
+       group->domain = NULL;
 
        /* Sets group->default_domain to the newly allocated domain */
        ret = iommu_group_alloc_default_domain(dev->bus, group, type);
        if (ret)
-               goto out;
+               goto restore_old_domain;
 
-       ret = iommu_create_device_direct_mappings(group, dev);
+       ret = iommu_group_create_direct_mappings(group);
        if (ret)
                goto free_new_domain;
 
-       ret = __iommu_attach_device(group->default_domain, dev);
+       ret = __iommu_attach_group(group->default_domain, group);
        if (ret)
                goto free_new_domain;
 
-       group->domain = group->default_domain;
        iommu_domain_free(prev_dom);
 
        return 0;
 
 free_new_domain:
        iommu_domain_free(group->default_domain);
+restore_old_domain:
        group->default_domain = prev_dom;
        group->domain = prev_dom;
-out:
+
        return ret;
 }