1 files changed, 252 insertions, 102 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 857d4c2fd1a2..847ad47a2dfd 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -18,7 +18,6 @@
 #include <linux/errno.h>
 #include <linux/iommu.h>
 #include <linux/idr.h>
-#include <linux/notifier.h>
 #include <linux/err.h>
 #include <linux/pci.h>
 #include <linux/bitops.h>
@@ -40,14 +39,16 @@ struct iommu_group {
 	struct kobject *devices_kobj;
 	struct list_head devices;
 	struct mutex mutex;
-	struct blocking_notifier_head notifier;
 	void *iommu_data;
 	void (*iommu_data_release)(void *iommu_data);
 	char *name;
 	int id;
 	struct iommu_domain *default_domain;
+	struct iommu_domain *blocking_domain;
 	struct iommu_domain *domain;
 	struct list_head entry;
+	unsigned int owner_cnt;
+	void *owner;
 };
 
 struct group_device {
@@ -82,8 +83,8 @@ static int __iommu_attach_device(struct iommu_domain *domain,
 				 struct device *dev);
 static int __iommu_attach_group(struct iommu_domain *domain,
 				struct iommu_group *group);
-static void __iommu_detach_group(struct iommu_domain *domain,
-				 struct iommu_group *group);
+static int __iommu_group_set_domain(struct iommu_group *group,
+				    struct iommu_domain *new_domain);
 static int iommu_create_device_direct_mappings(struct iommu_group *group,
 					       struct device *dev);
 static struct iommu_group *iommu_group_get_for_dev(struct device *dev);
@@ -294,7 +295,11 @@ int iommu_probe_device(struct device *dev)
 	mutex_lock(&group->mutex);
 	iommu_alloc_default_domain(group, dev);
 
-	if (group->default_domain) {
+	/*
+	 * If device joined an existing group which has been claimed, don't
+	 * attach the default domain.
+	 */
+	if (group->default_domain && !group->owner) {
 		ret = __iommu_attach_device(group->default_domain, dev);
 		if (ret) {
 			mutex_unlock(&group->mutex);
@@ -599,6 +604,8 @@ static void iommu_group_release(struct kobject *kobj)
 
 	if (group->default_domain)
 		iommu_domain_free(group->default_domain);
+	if (group->blocking_domain)
+		iommu_domain_free(group->blocking_domain);
 
 	kfree(group->name);
 	kfree(group);
@@ -633,7 +640,6 @@ struct iommu_group *iommu_group_alloc(void)
 	mutex_init(&group->mutex);
 	INIT_LIST_HEAD(&group->devices);
 	INIT_LIST_HEAD(&group->entry);
-	BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);
 
 	ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL);
 	if (ret < 0) {
@@ -906,10 +912,6 @@ rename:
 	if (ret)
 		goto err_put_group;
 
-	/* Notify any listeners about change to group. */
-	blocking_notifier_call_chain(&group->notifier,
-				     IOMMU_GROUP_NOTIFY_ADD_DEVICE, dev);
-
 	trace_add_device_to_group(group->id, dev);
 
 	dev_info(dev, "Adding to iommu group %d\n", group->id);
@@ -951,10 +953,6 @@ void iommu_group_remove_device(struct device *dev)
 
 	dev_info(dev, "Removing from iommu group %d\n", group->id);
 
-	/* Pre-notify listeners that a device is being removed. */
-	blocking_notifier_call_chain(&group->notifier,
-				     IOMMU_GROUP_NOTIFY_DEL_DEVICE, dev);
-
 	mutex_lock(&group->mutex);
 	list_for_each_entry(tmp_device, &group->devices, list) {
 		if (tmp_device->dev == dev) {
@@ -1077,36 +1075,6 @@ void iommu_group_put(struct iommu_group *group)
 EXPORT_SYMBOL_GPL(iommu_group_put);
 
 /**
- * iommu_group_register_notifier - Register a notifier for group changes
- * @group: the group to watch
- * @nb: notifier block to signal
- *
- * This function allows iommu group users to track changes in a group.
- * See include/linux/iommu.h for actions sent via this notifier.  Caller
- * should hold a reference to the group throughout notifier registration.
- */
-int iommu_group_register_notifier(struct iommu_group *group,
-				  struct notifier_block *nb)
-{
-	return blocking_notifier_chain_register(&group->notifier, nb);
-}
-EXPORT_SYMBOL_GPL(iommu_group_register_notifier);
-
-/**
- * iommu_group_unregister_notifier - Unregister a notifier
- * @group: the group to watch
- * @nb: notifier block to signal
- *
- * Unregister a previously registered group notifier block.
- */
-int iommu_group_unregister_notifier(struct iommu_group *group,
-				    struct notifier_block *nb)
-{
-	return blocking_notifier_chain_unregister(&group->notifier, nb);
-}
-EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier);
-
-/**
  * iommu_register_device_fault_handler() - Register a device fault handler
  * @dev: the device
  * @handler: the fault handler
@@ -1651,14 +1619,8 @@ static int remove_iommu_group(struct device *dev, void *data)
 static int iommu_bus_notifier(struct notifier_block *nb,
 			      unsigned long action, void *data)
 {
-	unsigned long group_action = 0;
 	struct device *dev = data;
-	struct iommu_group *group;
 
-	/*
-	 * ADD/DEL call into iommu driver ops if provided, which may
-	 * result in ADD/DEL notifiers to group->notifier
-	 */
 	if (action == BUS_NOTIFY_ADD_DEVICE) {
 		int ret;
 
@@ -1669,34 +1631,6 @@ static int iommu_bus_notifier(struct notifier_block *nb,
 		return NOTIFY_OK;
 	}
 
-	/*
-	 * Remaining BUS_NOTIFYs get filtered and republished to the
-	 * group, if anyone is listening
-	 */
-	group = iommu_group_get(dev);
-	if (!group)
-		return 0;
-
-	switch (action) {
-	case BUS_NOTIFY_BIND_DRIVER:
-		group_action = IOMMU_GROUP_NOTIFY_BIND_DRIVER;
-		break;
-	case BUS_NOTIFY_BOUND_DRIVER:
-		group_action = IOMMU_GROUP_NOTIFY_BOUND_DRIVER;
-		break;
-	case BUS_NOTIFY_UNBIND_DRIVER:
-		group_action = IOMMU_GROUP_NOTIFY_UNBIND_DRIVER;
-		break;
-	case BUS_NOTIFY_UNBOUND_DRIVER:
-		group_action = IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER;
-		break;
-	}
-
-	if (group_action)
-		blocking_notifier_call_chain(&group->notifier,
-					     group_action, dev);
-
-	iommu_group_put(group);
 	return 0;
 }
 
@@ -1913,6 +1847,29 @@ bool iommu_present(struct bus_type *bus)
 }
 EXPORT_SYMBOL_GPL(iommu_present);
 
+/**
+ * device_iommu_capable() - check for a general IOMMU capability
+ * @dev: device to which the capability would be relevant, if available
+ * @cap: IOMMU capability
+ *
+ * Return: true if an IOMMU is present and supports the given capability
+ * for the given device, otherwise false.
+ */
+bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
+{
+	const struct iommu_ops *ops;
+
+	if (!dev->iommu || !dev->iommu->iommu_dev)
+		return false;
+
+	ops = dev_iommu_ops(dev);
+	if (!ops->capable)
+		return false;
+
+	return ops->capable(cap);
+}
+EXPORT_SYMBOL_GPL(device_iommu_capable);
+
 bool iommu_capable(struct bus_type *bus, enum iommu_cap cap)
 {
 	if (!bus->iommu_ops || !bus->iommu_ops->capable)
@@ -1983,6 +1940,24 @@ void iommu_domain_free(struct iommu_domain *domain)
 }
 EXPORT_SYMBOL_GPL(iommu_domain_free);
 
+/*
+ * Put the group's domain back to the appropriate core-owned domain - either the
+ * standard kernel-mode DMA configuration or an all-DMA-blocked domain.
+ */
+static void __iommu_group_set_core_domain(struct iommu_group *group)
+{
+	struct iommu_domain *new_domain;
+	int ret;
+
+	if (group->owner)
+		new_domain = group->blocking_domain;
+	else
+		new_domain = group->default_domain;
+
+	ret = __iommu_group_set_domain(group, new_domain);
+	WARN(ret, "iommu driver failed to attach the default/blocking domain");
+}
+
 static int __iommu_attach_device(struct iommu_domain *domain,
 				 struct device *dev)
 {
@@ -2039,9 +2014,6 @@ static void __iommu_detach_device(struct iommu_domain *domain,
 	if (iommu_is_attach_deferred(dev))
 		return;
 
-	if (unlikely(domain->ops->detach_dev == NULL))
-		return;
-
 	domain->ops->detach_dev(domain, dev);
 	trace_detach_device_from_domain(dev);
 }
@@ -2055,12 +2027,10 @@ void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
 		return;
 
 	mutex_lock(&group->mutex);
-	if (iommu_group_device_count(group) != 1) {
-		WARN_ON(1);
+	if (WARN_ON(domain != group->domain) ||
+	    WARN_ON(iommu_group_device_count(group) != 1))
 		goto out_unlock;
-	}
-
-	__iommu_detach_group(domain, group);
+	__iommu_group_set_core_domain(group);
 
 out_unlock:
 	mutex_unlock(&group->mutex);
@@ -2116,7 +2086,8 @@ static int __iommu_attach_group(struct iommu_domain *domain,
 {
 	int ret;
 
-	if (group->default_domain && group->domain != group->default_domain)
+	if (group->domain && group->domain != group->default_domain &&
+	    group->domain != group->blocking_domain)
 		return -EBUSY;
 
 	ret = __iommu_group_for_each_dev(group, domain,
@@ -2148,34 +2119,49 @@ static int iommu_group_do_detach_device(struct device *dev, void *data)
 	return 0;
 }
 
-static void __iommu_detach_group(struct iommu_domain *domain,
-				 struct iommu_group *group)
+static int __iommu_group_set_domain(struct iommu_group *group,
+				    struct iommu_domain *new_domain)
 {
 	int ret;
 
-	if (!group->default_domain) {
-		__iommu_group_for_each_dev(group, domain,
+	if (group->domain == new_domain)
+		return 0;
+
+	/*
+	 * New drivers should support default domains and so the detach_dev() op
+	 * will never be called. Otherwise the NULL domain represents some
+	 * platform specific behavior.
+	 */
+	if (!new_domain) {
+		if (WARN_ON(!group->domain->ops->detach_dev))
+			return -EINVAL;
+		__iommu_group_for_each_dev(group, group->domain,
 					   iommu_group_do_detach_device);
 		group->domain = NULL;
-		return;
+		return 0;
 	}
 
-	if (group->domain == group->default_domain)
-		return;
-
-	/* Detach by re-attaching to the default domain */
-	ret = __iommu_group_for_each_dev(group, group->default_domain,
+	/*
+	 * Changing the domain is done by calling attach_dev() on the new
+	 * domain. This switch does not have to be atomic and DMA can be
+	 * discarded during the transition. DMA must only be able to access
+	 * either new_domain or group->domain, never something else.
+	 *
+	 * Note that this is called in error unwind paths, attaching to a
+	 * domain that has already been attached cannot fail.
+	 */
+	ret = __iommu_group_for_each_dev(group, new_domain,
 					 iommu_group_do_attach_device);
-	if (ret != 0)
-		WARN_ON(1);
-	else
-		group->domain = group->default_domain;
+	if (ret)
+		return ret;
+	group->domain = new_domain;
+	return 0;
 }
 
 void iommu_detach_group(struct iommu_domain *domain, struct iommu_group *group)
 {
 	mutex_lock(&group->mutex);
-	__iommu_detach_group(domain, group);
+	__iommu_group_set_core_domain(group);
 	mutex_unlock(&group->mutex);
 }
 EXPORT_SYMBOL_GPL(iommu_detach_group);
@@ -3102,3 +3088,167 @@ out:
 
 	return ret;
 }
+
+/**
+ * iommu_device_use_default_domain() - Device driver wants to handle device
+ *                                     DMA through the kernel DMA API.
+ * @dev: The device.
+ *
+ * The device driver about to bind @dev wants to do DMA through the kernel
+ * DMA API. Return 0 if it is allowed, otherwise an error.
+ */
+int iommu_device_use_default_domain(struct device *dev)
+{
+	struct iommu_group *group = iommu_group_get(dev);
+	int ret = 0;
+
+	if (!group)
+		return 0;
+
+	mutex_lock(&group->mutex);
+	if (group->owner_cnt) {
+		if (group->domain != group->default_domain ||
+		    group->owner) {
+			ret = -EBUSY;
+			goto unlock_out;
+		}
+	}
+
+	group->owner_cnt++;
+
+unlock_out:
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+
+	return ret;
+}
+
+/**
+ * iommu_device_unuse_default_domain() - Device driver stops handling device
+ *                                       DMA through the kernel DMA API.
+ * @dev: The device.
+ *
+ * The device driver doesn't want to do DMA through kernel DMA API anymore.
+ * It must be called after iommu_device_use_default_domain().
+ */
+void iommu_device_unuse_default_domain(struct device *dev)
+{
+	struct iommu_group *group = iommu_group_get(dev);
+
+	if (!group)
+		return;
+
+	mutex_lock(&group->mutex);
+	if (!WARN_ON(!group->owner_cnt))
+		group->owner_cnt--;
+
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+}
+
+static int __iommu_group_alloc_blocking_domain(struct iommu_group *group)
+{
+	struct group_device *dev =
+		list_first_entry(&group->devices, struct group_device, list);
+
+	if (group->blocking_domain)
+		return 0;
+
+	group->blocking_domain =
+		__iommu_domain_alloc(dev->dev->bus, IOMMU_DOMAIN_BLOCKED);
+	if (!group->blocking_domain) {
+		/*
+		 * For drivers that do not yet understand IOMMU_DOMAIN_BLOCKED
+		 * create an empty domain instead.
+		 */
+		group->blocking_domain = __iommu_domain_alloc(
+			dev->dev->bus, IOMMU_DOMAIN_UNMANAGED);
+		if (!group->blocking_domain)
+			return -EINVAL;
+	}
+	return 0;
+}
+
+/**
+ * iommu_group_claim_dma_owner() - Set DMA ownership of a group
+ * @group: The group.
+ * @owner: Caller specified pointer. Used for exclusive ownership.
+ *
+ * This is to support backward compatibility for vfio which manages
+ * the dma ownership in iommu_group level. New invocations on this
+ * interface should be prohibited.
+ */
+int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner)
+{
+	int ret = 0;
+
+	mutex_lock(&group->mutex);
+	if (group->owner_cnt) {
+		ret = -EPERM;
+		goto unlock_out;
+	} else {
+		if (group->domain && group->domain != group->default_domain) {
+			ret = -EBUSY;
+			goto unlock_out;
+		}
+
+		ret = __iommu_group_alloc_blocking_domain(group);
+		if (ret)
+			goto unlock_out;
+
+		ret = __iommu_group_set_domain(group, group->blocking_domain);
+		if (ret)
+			goto unlock_out;
+		group->owner = owner;
+	}
+
+	group->owner_cnt++;
+unlock_out:
+	mutex_unlock(&group->mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner);
+
+/**
+ * iommu_group_release_dma_owner() - Release DMA ownership of a group
+ * @group: The group.
+ *
+ * Release the DMA ownership claimed by iommu_group_claim_dma_owner().
+ */
+void iommu_group_release_dma_owner(struct iommu_group *group)
+{
+	int ret;
+
+	mutex_lock(&group->mutex);
+	if (WARN_ON(!group->owner_cnt || !group->owner))
+		goto unlock_out;
+
+	group->owner_cnt = 0;
+	group->owner = NULL;
+	ret = __iommu_group_set_domain(group, group->default_domain);
+	WARN(ret, "iommu driver failed to attach the default domain");
+
+unlock_out:
+	mutex_unlock(&group->mutex);
+}
+EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner);
+
+/**
+ * iommu_group_dma_owner_claimed() - Query group dma ownership status
+ * @group: The group.
+ *
+ * This provides status query on a given group. It is racy and only for
+ * non-binding status reporting.
+ */
+bool iommu_group_dma_owner_claimed(struct iommu_group *group)
+{
+	unsigned int user;
+
+	mutex_lock(&group->mutex);
+	user = group->owner_cnt;
+	mutex_unlock(&group->mutex);
+
+	return user;
+}
+EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);