1 files changed, 136 insertions, 202 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 256a38371120..153a3dab568c 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -87,6 +87,7 @@ static const char * const iommu_group_resv_type_string[] = {
 
 static int iommu_bus_notifier(struct notifier_block *nb,
 			      unsigned long action, void *data);
+static void iommu_release_device(struct device *dev);
 static int iommu_alloc_default_domain(struct iommu_group *group,
 				      struct device *dev);
 static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
@@ -453,20 +454,86 @@ err_out:
 
 }
 
-void iommu_release_device(struct device *dev)
+/*
+ * Remove a device from a group's device list and return the group device
+ * if successful.
+ */
+static struct group_device *
+__iommu_group_remove_device(struct iommu_group *group, struct device *dev)
+{
+	struct group_device *device;
+
+	lockdep_assert_held(&group->mutex);
+	list_for_each_entry(device, &group->devices, list) {
+		if (device->dev == dev) {
+			list_del(&device->list);
+			return device;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * Release a device from its group and decrements the iommu group reference
+ * count.
+ */
+static void __iommu_group_release_device(struct iommu_group *group,
+					 struct group_device *grp_dev)
+{
+	struct device *dev = grp_dev->dev;
+
+	sysfs_remove_link(group->devices_kobj, grp_dev->name);
+	sysfs_remove_link(&dev->kobj, "iommu_group");
+
+	trace_remove_device_from_group(group->id, dev);
+
+	kfree(grp_dev->name);
+	kfree(grp_dev);
+	dev->iommu_group = NULL;
+	kobject_put(group->devices_kobj);
+}
+
+static void iommu_release_device(struct device *dev)
 {
+	struct iommu_group *group = dev->iommu_group;
+	struct group_device *device;
 	const struct iommu_ops *ops;
 
-	if (!dev->iommu)
+	if (!dev->iommu || !group)
 		return;
 
 	iommu_device_unlink(dev->iommu->iommu_dev, dev);
 
+	mutex_lock(&group->mutex);
+	device = __iommu_group_remove_device(group, dev);
+
+	/*
+	 * If the group has become empty then ownership must have been released,
+	 * and the current domain must be set back to NULL or the default
+	 * domain.
+	 */
+	if (list_empty(&group->devices))
+		WARN_ON(group->owner_cnt ||
+			group->domain != group->default_domain);
+
+	/*
+	 * release_device() must stop using any attached domain on the device.
+	 * If there are still other devices in the group they are not effected
+	 * by this callback.
+	 *
+	 * The IOMMU driver must set the device to either an identity or
+	 * blocking translation and stop using any domain pointer, as it is
+	 * going to be freed.
+	 */
 	ops = dev_iommu_ops(dev);
 	if (ops->release_device)
 		ops->release_device(dev);
+	mutex_unlock(&group->mutex);
+
+	if (device)
+		__iommu_group_release_device(group, device);
 
-	iommu_group_remove_device(dev);
 	module_put(ops->owner);
 	dev_iommu_free(dev);
 }
@@ -550,7 +617,7 @@ static void iommu_group_remove_file(struct iommu_group *group,
 
 static ssize_t iommu_group_show_name(struct iommu_group *group, char *buf)
 {
-	return sprintf(buf, "%s\n", group->name);
+	return sysfs_emit(buf, "%s\n", group->name);
 }
 
 /**
@@ -663,52 +730,51 @@ static ssize_t iommu_group_show_resv_regions(struct iommu_group *group,
 {
 	struct iommu_resv_region *region, *next;
 	struct list_head group_resv_regions;
-	char *str = buf;
+	int offset = 0;
 
 	INIT_LIST_HEAD(&group_resv_regions);
 	iommu_get_group_resv_regions(group, &group_resv_regions);
 
 	list_for_each_entry_safe(region, next, &group_resv_regions, list) {
-		str += sprintf(str, "0x%016llx 0x%016llx %s\n",
-			       (long long int)region->start,
-			       (long long int)(region->start +
-						region->length - 1),
-			       iommu_group_resv_type_string[region->type]);
+		offset += sysfs_emit_at(buf, offset, "0x%016llx 0x%016llx %s\n",
+					(long long)region->start,
+					(long long)(region->start +
+						    region->length - 1),
+					iommu_group_resv_type_string[region->type]);
 		kfree(region);
 	}
 
-	return (str - buf);
+	return offset;
 }
 
 static ssize_t iommu_group_show_type(struct iommu_group *group,
 				     char *buf)
 {
-	char *type = "unknown\n";
+	char *type = "unknown";
 
 	mutex_lock(&group->mutex);
 	if (group->default_domain) {
 		switch (group->default_domain->type) {
 		case IOMMU_DOMAIN_BLOCKED:
-			type = "blocked\n";
+			type = "blocked";
 			break;
 		case IOMMU_DOMAIN_IDENTITY:
-			type = "identity\n";
+			type = "identity";
 			break;
 		case IOMMU_DOMAIN_UNMANAGED:
-			type = "unmanaged\n";
+			type = "unmanaged";
 			break;
 		case IOMMU_DOMAIN_DMA:
-			type = "DMA\n";
+			type = "DMA";
 			break;
 		case IOMMU_DOMAIN_DMA_FQ:
-			type = "DMA-FQ\n";
+			type = "DMA-FQ";
 			break;
 		}
 	}
 	mutex_unlock(&group->mutex);
-	strcpy(buf, type);
 
-	return strlen(type);
+	return sysfs_emit(buf, "%s\n", type);
 }
 
 static IOMMU_GROUP_ATTR(name, S_IRUGO, iommu_group_show_name, NULL);
@@ -739,7 +805,7 @@ static void iommu_group_release(struct kobject *kobj)
 	kfree(group);
 }
 
-static struct kobj_type iommu_group_ktype = {
+static const struct kobj_type iommu_group_ktype = {
 	.sysfs_ops = &iommu_group_sysfs_ops,
 	.release = iommu_group_release,
 };
@@ -816,35 +882,6 @@ struct iommu_group *iommu_group_alloc(void)
 }
 EXPORT_SYMBOL_GPL(iommu_group_alloc);
 
-struct iommu_group *iommu_group_get_by_id(int id)
-{
-	struct kobject *group_kobj;
-	struct iommu_group *group;
-	const char *name;
-
-	if (!iommu_group_kset)
-		return NULL;
-
-	name = kasprintf(GFP_KERNEL, "%d", id);
-	if (!name)
-		return NULL;
-
-	group_kobj = kset_find_obj(iommu_group_kset, name);
-	kfree(name);
-
-	if (!group_kobj)
-		return NULL;
-
-	group = container_of(group_kobj, struct iommu_group, kobj);
-	BUG_ON(group->id != id);
-
-	kobject_get(group->devices_kobj);
-	kobject_put(&group->kobj);
-
-	return group;
-}
-EXPORT_SYMBOL_GPL(iommu_group_get_by_id);
-
 /**
  * iommu_group_get_iommudata - retrieve iommu_data registered for a group
  * @group: the group
@@ -1068,7 +1105,7 @@ EXPORT_SYMBOL_GPL(iommu_group_add_device);
 void iommu_group_remove_device(struct device *dev)
 {
 	struct iommu_group *group = dev->iommu_group;
-	struct group_device *tmp_device, *device = NULL;
+	struct group_device *device;
 
 	if (!group)
 		return;
@@ -1076,27 +1113,11 @@ void iommu_group_remove_device(struct device *dev)
 	dev_info(dev, "Removing from iommu group %d\n", group->id);
 
 	mutex_lock(&group->mutex);
-	list_for_each_entry(tmp_device, &group->devices, list) {
-		if (tmp_device->dev == dev) {
-			device = tmp_device;
-			list_del(&device->list);
-			break;
-		}
-	}
+	device = __iommu_group_remove_device(group, dev);
 	mutex_unlock(&group->mutex);
 
-	if (!device)
-		return;
-
-	sysfs_remove_link(group->devices_kobj, device->name);
-	sysfs_remove_link(&dev->kobj, "iommu_group");
-
-	trace_remove_device_from_group(group->id, dev);
-
-	kfree(device->name);
-	kfree(device);
-	dev->iommu_group = NULL;
-	kobject_put(group->devices_kobj);
+	if (device)
+		__iommu_group_release_device(group, device);
 }
 EXPORT_SYMBOL_GPL(iommu_group_remove_device);
 
@@ -2822,11 +2843,10 @@ 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
@@ -2837,124 +2857,63 @@ 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;
-
-	mutex_lock(&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;
+	int ret;
 
-	if (prev_dev != dev) {
-		dev_err_ratelimited(prev_dev, "Cannot change default domain: Device has been changed\n");
-		ret = -EBUSY;
-		goto out;
-	}
+	lockdep_assert_held(&group->mutex);
 
 	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;
 
-	/* We can bring up a flush queue without tearing down the domain */
-	if (type == IOMMU_DOMAIN_DMA_FQ && prev_dom->type == IOMMU_DOMAIN_DMA) {
-		ret = iommu_dma_init_fq(prev_dom);
-		if (!ret)
-			prev_dom->type = IOMMU_DOMAIN_DMA_FQ;
-		goto out;
-	}
+	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;
-
-	/*
-	 * Release the mutex here because ops->probe_finalize() call-back of
-	 * some vendor IOMMU drivers calls arm_iommu_attach_device() which
-	 * in-turn might call back into IOMMU core code, where it tries to take
-	 * group->mutex, resulting in a deadlock.
-	 */
-	mutex_unlock(&group->mutex);
-
-	/* Make sure dma_ops is appropriatley set */
-	iommu_group_do_probe_finalize(dev, 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:
-	mutex_unlock(&group->mutex);
-
 	return ret;
 }
 
@@ -2964,7 +2923,7 @@ out:
  * transition. Return failure if this isn't met.
  *
  * We need to consider the race between this and the device release path.
- * device_lock(dev) is used here to guarantee that the device release path
+ * group->mutex is used here to guarantee that the device release path
  * will not be entered at the same time.
  */
 static ssize_t iommu_group_store_type(struct iommu_group *group,
@@ -2991,67 +2950,42 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
 	else
 		return -EINVAL;
 
-	/*
-	 * Lock/Unlock the group mutex here before device lock to
-	 * 1. Make sure that the iommu group has only one device (this is a
-	 *    prerequisite for step 2)
-	 * 2. Get struct *dev which is needed to lock device
-	 */
 	mutex_lock(&group->mutex);
-	if (iommu_group_device_count(group) != 1) {
+	/* We can bring up a flush queue without tearing down the domain. */
+	if (req_type == IOMMU_DOMAIN_DMA_FQ &&
+	    group->default_domain->type == IOMMU_DOMAIN_DMA) {
+		ret = iommu_dma_init_fq(group->default_domain);
+		if (!ret)
+			group->default_domain->type = IOMMU_DOMAIN_DMA_FQ;
 		mutex_unlock(&group->mutex);
-		pr_err_ratelimited("Cannot change default domain: Group has more than one device\n");
-		return -EINVAL;
+
+		return ret ?: count;
+	}
+
+	/* Otherwise, ensure that device exists and no driver is bound. */
+	if (list_empty(&group->devices) || group->owner_cnt) {
+		mutex_unlock(&group->mutex);
+		return -EPERM;
 	}
 
-	/* Since group has only one device */
 	grp_dev = list_first_entry(&group->devices, struct group_device, list);
 	dev = grp_dev->dev;
-	get_device(dev);
+
+	ret = iommu_change_dev_def_domain(group, dev, req_type);
 
 	/*
-	 * Don't hold the group mutex because taking group mutex first and then
-	 * the device lock could potentially cause a deadlock as below. Assume
-	 * two threads T1 and T2. T1 is trying to change default domain of an
-	 * iommu group and T2 is trying to hot unplug a device or release [1] VF
-	 * of a PCIe device which is in the same iommu group. T1 takes group
-	 * mutex and before it could take device lock assume T2 has taken device
-	 * lock and is yet to take group mutex. Now, both the threads will be
-	 * waiting for the other thread to release lock. Below, lock order was
-	 * suggested.
-	 * device_lock(dev);
-	 *	mutex_lock(&group->mutex);
-	 *		iommu_change_dev_def_domain();
-	 *	mutex_unlock(&group->mutex);
-	 * device_unlock(dev);
-	 *
-	 * [1] Typical device release path
-	 * device_lock() from device/driver core code
-	 *  -> bus_notifier()
-	 *   -> iommu_bus_notifier()
-	 *    -> iommu_release_device()
-	 *     -> ops->release_device() vendor driver calls back iommu core code
-	 *      -> mutex_lock() from iommu core code
+	 * Release the mutex here because ops->probe_finalize() call-back of
+	 * some vendor IOMMU drivers calls arm_iommu_attach_device() which
+	 * in-turn might call back into IOMMU core code, where it tries to take
+	 * group->mutex, resulting in a deadlock.
 	 */
 	mutex_unlock(&group->mutex);
 
-	/* Check if the device in the group still has a driver bound to it */
-	device_lock(dev);
-	if (device_is_bound(dev) && !(req_type == IOMMU_DOMAIN_DMA_FQ &&
-	    group->default_domain->type == IOMMU_DOMAIN_DMA)) {
-		pr_err_ratelimited("Device is still bound to driver\n");
-		ret = -EBUSY;
-		goto out;
-	}
-
-	ret = iommu_change_dev_def_domain(group, dev, req_type);
-	ret = ret ?: count;
-
-out:
-	device_unlock(dev);
-	put_device(dev);
+	/* Make sure dma_ops is appropriatley set */
+	if (!ret)
+		__iommu_group_dma_finalize(group);
 
-	return ret;
+	return ret ?: count;
 }
 
 static bool iommu_is_default_domain(struct iommu_group *group)