1 files changed, 367 insertions, 81 deletions

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 59e36ef4920f..5bdc6b82b30b 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -1,8 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/virtio.h>
 #include <linux/spinlock.h>
 #include <linux/virtio_config.h>
+#include <linux/virtio_anchor.h>
 #include <linux/module.h>
 #include <linux/idr.h>
+#include <linux/of.h>
 #include <uapi/linux/virtio_ids.h>
 
 /* Unique numbering for virtio devices. */
@@ -12,7 +15,7 @@ static ssize_t device_show(struct device *_d,
 			   struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "0x%04x\n", dev->id.device);
+	return sysfs_emit(buf, "0x%04x\n", dev->id.device);
 }
 static DEVICE_ATTR_RO(device);
 
@@ -20,7 +23,7 @@ static ssize_t vendor_show(struct device *_d,
 			   struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "0x%04x\n", dev->id.vendor);
+	return sysfs_emit(buf, "0x%04x\n", dev->id.vendor);
 }
 static DEVICE_ATTR_RO(vendor);
 
@@ -28,7 +31,7 @@ static ssize_t status_show(struct device *_d,
 			   struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
+	return sysfs_emit(buf, "0x%08x\n", dev->config->get_status(dev));
 }
 static DEVICE_ATTR_RO(status);
 
@@ -36,7 +39,7 @@ static ssize_t modalias_show(struct device *_d,
 			     struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "virtio:d%08Xv%08X\n",
+	return sysfs_emit(buf, "virtio:d%08Xv%08X\n",
 		       dev->id.device, dev->id.vendor);
 }
 static DEVICE_ATTR_RO(modalias);
@@ -50,10 +53,10 @@ static ssize_t features_show(struct device *_d,
 
 	/* We actually represent this as a bitstring, as it could be
 	 * arbitrary length in future. */
-	for (i = 0; i < sizeof(dev->features)*8; i++)
-		len += sprintf(buf+len, "%c",
+	for (i = 0; i < VIRTIO_FEATURES_BITS; i++)
+		len += sysfs_emit_at(buf, len, "%c",
 			       __virtio_test_bit(dev, i) ? '1' : '0');
-	len += sprintf(buf+len, "\n");
+	len += sysfs_emit_at(buf, len, "\n");
 	return len;
 }
 static DEVICE_ATTR_RO(features);
@@ -79,7 +82,7 @@ static inline int virtio_id_match(const struct virtio_device *dev,
 
 /* This looks through all the IDs a driver claims to support.  If any of them
  * match, we return 1 and the kernel will call virtio_dev_probe(). */
-static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
+static int virtio_dev_match(struct device *_dv, const struct device_driver *_dr)
 {
 	unsigned int i;
 	struct virtio_device *dev = dev_to_virtio(_dv);
@@ -92,9 +95,9 @@ static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
 	return 0;
 }
 
-static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
+static int virtio_uevent(const struct device *_dv, struct kobj_uevent_env *env)
 {
-	struct virtio_device *dev = dev_to_virtio(_dv);
+	const struct virtio_device *dev = dev_to_virtio(_dv);
 
 	return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
 			      dev->id.device, dev->id.vendor);
@@ -124,10 +127,12 @@ static void __virtio_config_changed(struct virtio_device *dev)
 {
 	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 
-	if (!dev->config_enabled)
+	if (!dev->config_core_enabled || dev->config_driver_disabled)
 		dev->config_change_pending = true;
-	else if (drv && drv->config_changed)
+	else if (drv && drv->config_changed) {
 		drv->config_changed(dev);
+		dev->config_change_pending = false;
+	}
 }
 
 void virtio_config_changed(struct virtio_device *dev)
@@ -140,38 +145,81 @@ void virtio_config_changed(struct virtio_device *dev)
 }
 EXPORT_SYMBOL_GPL(virtio_config_changed);
 
-void virtio_config_disable(struct virtio_device *dev)
+/**
+ * virtio_config_driver_disable - disable config change reporting by drivers
+ * @dev: the device to disable
+ *
+ * This is only allowed to be called by a driver and disabling can't
+ * be nested.
+ */
+void virtio_config_driver_disable(struct virtio_device *dev)
 {
 	spin_lock_irq(&dev->config_lock);
-	dev->config_enabled = false;
+	dev->config_driver_disabled = true;
 	spin_unlock_irq(&dev->config_lock);
 }
-EXPORT_SYMBOL_GPL(virtio_config_disable);
+EXPORT_SYMBOL_GPL(virtio_config_driver_disable);
 
-void virtio_config_enable(struct virtio_device *dev)
+/**
+ * virtio_config_driver_enable - enable config change reporting by drivers
+ * @dev: the device to enable
+ *
+ * This is only allowed to be called by a driver and enabling can't
+ * be nested.
+ */
+void virtio_config_driver_enable(struct virtio_device *dev)
 {
 	spin_lock_irq(&dev->config_lock);
-	dev->config_enabled = true;
+	dev->config_driver_disabled = false;
+	if (dev->config_change_pending)
+		__virtio_config_changed(dev);
+	spin_unlock_irq(&dev->config_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_config_driver_enable);
+
+static void virtio_config_core_disable(struct virtio_device *dev)
+{
+	spin_lock_irq(&dev->config_lock);
+	dev->config_core_enabled = false;
+	spin_unlock_irq(&dev->config_lock);
+}
+
+static void virtio_config_core_enable(struct virtio_device *dev)
+{
+	spin_lock_irq(&dev->config_lock);
+	dev->config_core_enabled = true;
 	if (dev->config_change_pending)
 		__virtio_config_changed(dev);
-	dev->config_change_pending = false;
 	spin_unlock_irq(&dev->config_lock);
 }
-EXPORT_SYMBOL_GPL(virtio_config_enable);
 
 void virtio_add_status(struct virtio_device *dev, unsigned int status)
 {
+	might_sleep();
 	dev->config->set_status(dev, dev->config->get_status(dev) | status);
 }
 EXPORT_SYMBOL_GPL(virtio_add_status);
 
-int virtio_finalize_features(struct virtio_device *dev)
+/* Do some validation, then set FEATURES_OK */
+static int virtio_features_ok(struct virtio_device *dev)
 {
-	int ret = dev->config->finalize_features(dev);
-	unsigned status;
+	unsigned int status;
 
-	if (ret)
-		return ret;
+	might_sleep();
+
+	if (virtio_check_mem_acc_cb(dev)) {
+		if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+			dev_warn(&dev->dev,
+				 "device must provide VIRTIO_F_VERSION_1\n");
+			return -ENODEV;
+		}
+
+		if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) {
+			dev_warn(&dev->dev,
+				 "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
+			return -ENODEV;
+		}
+	}
 
 	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 		return 0;
@@ -185,29 +233,61 @@ int virtio_finalize_features(struct virtio_device *dev)
 	}
 	return 0;
 }
-EXPORT_SYMBOL_GPL(virtio_finalize_features);
+
+/**
+ * virtio_reset_device - quiesce device for removal
+ * @dev: the device to reset
+ *
+ * Prevents device from sending interrupts and accessing memory.
+ *
+ * Generally used for cleanup during driver / device removal.
+ *
+ * Once this has been invoked, caller must ensure that
+ * virtqueue_notify / virtqueue_kick are not in progress.
+ *
+ * Note: this guarantees that vq callbacks are not in progress, however caller
+ * is responsible for preventing access from other contexts, such as a system
+ * call/workqueue/bh.  Invoking virtio_break_device then flushing any such
+ * contexts is one way to handle that.
+ * */
+void virtio_reset_device(struct virtio_device *dev)
+{
+#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+	/*
+	 * The below virtio_synchronize_cbs() guarantees that any
+	 * interrupt for this line arriving after
+	 * virtio_synchronize_vqs() has completed is guaranteed to see
+	 * vq->broken as true.
+	 */
+	virtio_break_device(dev);
+	virtio_synchronize_cbs(dev);
+#endif
+
+	dev->config->reset(dev);
+}
+EXPORT_SYMBOL_GPL(virtio_reset_device);
 
 static int virtio_dev_probe(struct device *_d)
 {
 	int err, i;
 	struct virtio_device *dev = dev_to_virtio(_d);
 	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
-	u64 device_features;
-	u64 driver_features;
+	u64 device_features[VIRTIO_FEATURES_U64S];
+	u64 driver_features[VIRTIO_FEATURES_U64S];
 	u64 driver_features_legacy;
 
 	/* We have a driver! */
 	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 
 	/* Figure out what features the device supports. */
-	device_features = dev->config->get_features(dev);
+	virtio_get_features(dev, device_features);
 
 	/* Figure out what features the driver supports. */
-	driver_features = 0;
+	virtio_features_zero(driver_features);
 	for (i = 0; i < drv->feature_table_size; i++) {
 		unsigned int f = drv->feature_table[i];
-		BUG_ON(f >= 64);
-		driver_features |= (1ULL << f);
+		if (!WARN_ON_ONCE(f >= VIRTIO_FEATURES_BITS))
+			virtio_features_set_bit(driver_features, f);
 	}
 
 	/* Some drivers have a separate feature table for virtio v1.0 */
@@ -215,30 +295,52 @@ static int virtio_dev_probe(struct device *_d)
 		driver_features_legacy = 0;
 		for (i = 0; i < drv->feature_table_size_legacy; i++) {
 			unsigned int f = drv->feature_table_legacy[i];
-			BUG_ON(f >= 64);
-			driver_features_legacy |= (1ULL << f);
+			if (!WARN_ON_ONCE(f >= 64))
+				driver_features_legacy |= (1ULL << f);
 		}
 	} else {
-		driver_features_legacy = driver_features;
+		driver_features_legacy = driver_features[0];
 	}
 
-	if (device_features & (1ULL << VIRTIO_F_VERSION_1))
-		dev->features = driver_features & device_features;
-	else
-		dev->features = driver_features_legacy & device_features;
+	if (virtio_features_test_bit(device_features, VIRTIO_F_VERSION_1)) {
+		for (i = 0; i < VIRTIO_FEATURES_U64S; ++i)
+			dev->features_array[i] = driver_features[i] &
+						 device_features[i];
+	} else {
+		virtio_features_from_u64(dev->features_array,
+					 driver_features_legacy &
+					 device_features[0]);
+	}
+
+	/* When debugging, user may filter some features by hand. */
+	virtio_debug_device_filter_features(dev);
 
 	/* Transport features always preserved to pass to finalize_features. */
 	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
-		if (device_features & (1ULL << i))
+		if (virtio_features_test_bit(device_features, i))
 			__virtio_set_bit(dev, i);
 
+	err = dev->config->finalize_features(dev);
+	if (err)
+		goto err;
+
 	if (drv->validate) {
+		u64 features[VIRTIO_FEATURES_U64S];
+
+		virtio_features_copy(features, dev->features_array);
 		err = drv->validate(dev);
 		if (err)
 			goto err;
+
+		/* Did validation change any features? Then write them again. */
+		if (!virtio_features_equal(features, dev->features_array)) {
+			err = dev->config->finalize_features(dev);
+			if (err)
+				goto err;
+		}
 	}
 
-	err = virtio_finalize_features(dev);
+	err = virtio_features_ok(dev);
 	if (err)
 		goto err;
 
@@ -253,21 +355,22 @@ static int virtio_dev_probe(struct device *_d)
 	if (drv->scan)
 		drv->scan(dev);
 
-	virtio_config_enable(dev);
+	virtio_config_core_enable(dev);
 
 	return 0;
+
 err:
 	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 	return err;
 
 }
 
-static int virtio_dev_remove(struct device *_d)
+static void virtio_dev_remove(struct device *_d)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
 	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 
-	virtio_config_disable(dev);
+	virtio_config_core_disable(dev);
 
 	drv->remove(dev);
 
@@ -276,26 +379,83 @@ static int virtio_dev_remove(struct device *_d)
 
 	/* Acknowledge the device's existence again. */
 	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
-	return 0;
+
+	of_node_put(dev->dev.of_node);
 }
 
-static struct bus_type virtio_bus = {
+/*
+ * virtio_irq_get_affinity - get IRQ affinity mask for device
+ * @_d: ptr to dev structure
+ * @irq_vec: interrupt vector number
+ *
+ * Return the CPU affinity mask for @_d and @irq_vec.
+ */
+static const struct cpumask *virtio_irq_get_affinity(struct device *_d,
+						     unsigned int irq_vec)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+
+	if (!dev->config->get_vq_affinity)
+		return NULL;
+
+	return dev->config->get_vq_affinity(dev, irq_vec);
+}
+
+static void virtio_dev_shutdown(struct device *_d)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+
+	/*
+	 * Stop accesses to or from the device.
+	 * We only need to do it if there's a driver - no accesses otherwise.
+	 */
+	if (!drv)
+		return;
+
+	/* If the driver has its own shutdown method, use that. */
+	if (drv->shutdown) {
+		drv->shutdown(dev);
+		return;
+	}
+
+	/*
+	 * Some devices get wedged if you kick them after they are
+	 * reset. Mark all vqs as broken to make sure we don't.
+	 */
+	virtio_break_device(dev);
+	/*
+	 * Guarantee that any callback will see vq->broken as true.
+	 */
+	virtio_synchronize_cbs(dev);
+	/*
+	 * As IOMMUs are reset on shutdown, this will block device access to memory.
+	 * Some devices get wedged if this happens, so reset to make sure it does not.
+	 */
+	dev->config->reset(dev);
+}
+
+static const struct bus_type virtio_bus = {
 	.name  = "virtio",
 	.match = virtio_dev_match,
 	.dev_groups = virtio_dev_groups,
 	.uevent = virtio_uevent,
 	.probe = virtio_dev_probe,
 	.remove = virtio_dev_remove,
+	.irq_get_affinity = virtio_irq_get_affinity,
+	.shutdown = virtio_dev_shutdown,
 };
 
-int register_virtio_driver(struct virtio_driver *driver)
+int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
 {
 	/* Catch this early. */
 	BUG_ON(driver->feature_table_size && !driver->feature_table);
 	driver->driver.bus = &virtio_bus;
+	driver->driver.owner = owner;
+
 	return driver_register(&driver->driver);
 }
-EXPORT_SYMBOL_GPL(register_virtio_driver);
+EXPORT_SYMBOL_GPL(__register_virtio_driver);
 
 void unregister_virtio_driver(struct virtio_driver *driver)
 {
@@ -303,6 +463,48 @@ void unregister_virtio_driver(struct virtio_driver *driver)
 }
 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 
+static int virtio_device_of_init(struct virtio_device *dev)
+{
+	struct device_node *np, *pnode = dev_of_node(dev->dev.parent);
+	char compat[] = "virtio,deviceXXXXXXXX";
+	int ret, count;
+
+	if (!pnode)
+		return 0;
+
+	count = of_get_available_child_count(pnode);
+	if (!count)
+		return 0;
+
+	/* There can be only 1 child node */
+	if (WARN_ON(count > 1))
+		return -EINVAL;
+
+	np = of_get_next_available_child(pnode, NULL);
+	if (WARN_ON(!np))
+		return -ENODEV;
+
+	ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device);
+	BUG_ON(ret >= sizeof(compat));
+
+	/*
+	 * On powerpc/pseries virtio devices are PCI devices so PCI
+	 * vendor/device ids play the role of the "compatible" property.
+	 * Simply don't init of_node in this case.
+	 */
+	if (!of_device_is_compatible(np, compat)) {
+		ret = 0;
+		goto out;
+	}
+
+	dev->dev.of_node = np;
+	return 0;
+
+out:
+	of_node_put(np);
+	return ret;
+}
+
 /**
  * register_virtio_device - register virtio device
  * @dev        : virtio device to be registered
@@ -310,7 +512,7 @@ EXPORT_SYMBOL_GPL(unregister_virtio_driver);
  * On error, the caller must call put_device on &@dev->dev (and not kfree),
  * as another code path may have obtained a reference to @dev.
  *
- * Returns: 0 on suceess, -error on failure
+ * Returns: 0 on success, -error on failure
  */
 int register_virtio_device(struct virtio_device *dev)
 {
@@ -320,25 +522,35 @@ int register_virtio_device(struct virtio_device *dev)
 	device_initialize(&dev->dev);
 
 	/* Assign a unique device index and hence name. */
-	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
+	err = ida_alloc(&virtio_index_ida, GFP_KERNEL);
 	if (err < 0)
 		goto out;
 
 	dev->index = err;
-	dev_set_name(&dev->dev, "virtio%u", dev->index);
+	err = dev_set_name(&dev->dev, "virtio%u", dev->index);
+	if (err)
+		goto out_ida_remove;
+
+	err = virtio_device_of_init(dev);
+	if (err)
+		goto out_ida_remove;
 
 	spin_lock_init(&dev->config_lock);
-	dev->config_enabled = false;
+	dev->config_driver_disabled = false;
+	dev->config_core_enabled = false;
 	dev->config_change_pending = false;
 
+	INIT_LIST_HEAD(&dev->vqs);
+	spin_lock_init(&dev->vqs_list_lock);
+
 	/* We always start by resetting the device, in case a previous
 	 * driver messed it up.  This also tests that code path a little. */
-	dev->config->reset(dev);
+	virtio_reset_device(dev);
 
 	/* Acknowledge that we've seen the device. */
 	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 
-	INIT_LIST_HEAD(&dev->vqs);
+	virtio_debug_device_init(dev);
 
 	/*
 	 * device_add() causes the bus infrastructure to look for a matching
@@ -346,47 +558,44 @@ int register_virtio_device(struct virtio_device *dev)
 	 */
 	err = device_add(&dev->dev);
 	if (err)
-		ida_simple_remove(&virtio_index_ida, dev->index);
+		goto out_of_node_put;
+
+	return 0;
+
+out_of_node_put:
+	of_node_put(dev->dev.of_node);
+out_ida_remove:
+	ida_free(&virtio_index_ida, dev->index);
 out:
-	if (err)
-		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 	return err;
 }
 EXPORT_SYMBOL_GPL(register_virtio_device);
 
+bool is_virtio_device(struct device *dev)
+{
+	return dev->bus == &virtio_bus;
+}
+EXPORT_SYMBOL_GPL(is_virtio_device);
+
 void unregister_virtio_device(struct virtio_device *dev)
 {
 	int index = dev->index; /* save for after device release */
 
 	device_unregister(&dev->dev);
-	ida_simple_remove(&virtio_index_ida, index);
+	virtio_debug_device_exit(dev);
+	ida_free(&virtio_index_ida, index);
 }
 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 
-#ifdef CONFIG_PM_SLEEP
-int virtio_device_freeze(struct virtio_device *dev)
-{
-	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
-
-	virtio_config_disable(dev);
-
-	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
-
-	if (drv && drv->freeze)
-		return drv->freeze(dev);
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(virtio_device_freeze);
-
-int virtio_device_restore(struct virtio_device *dev)
+static int virtio_device_restore_priv(struct virtio_device *dev, bool restore)
 {
 	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 	int ret;
 
 	/* We always start by resetting the device, in case a previous
 	 * driver messed it up. */
-	dev->config->reset(dev);
+	virtio_reset_device(dev);
 
 	/* Acknowledge that we've seen the device. */
 	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
@@ -402,20 +611,31 @@ int virtio_device_restore(struct virtio_device *dev)
 	/* We have a driver! */
 	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 
-	ret = virtio_finalize_features(dev);
+	ret = dev->config->finalize_features(dev);
+	if (ret)
+		goto err;
+
+	ret = virtio_features_ok(dev);
 	if (ret)
 		goto err;
 
-	if (drv->restore) {
-		ret = drv->restore(dev);
+	if (restore) {
+		if (drv->restore) {
+			ret = drv->restore(dev);
+			if (ret)
+				goto err;
+		}
+	} else {
+		ret = drv->reset_done(dev);
 		if (ret)
 			goto err;
 	}
 
-	/* Finally, tell the device we're all set */
-	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
+	/* If restore didn't do it, mark device DRIVER_OK ourselves. */
+	if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
+		virtio_device_ready(dev);
 
-	virtio_config_enable(dev);
+	virtio_config_core_enable(dev);
 
 	return 0;
 
@@ -423,22 +643,88 @@ err:
 	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 	return ret;
 }
+
+#ifdef CONFIG_PM_SLEEP
+int virtio_device_freeze(struct virtio_device *dev)
+{
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+	int ret;
+
+	virtio_config_core_disable(dev);
+
+	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
+
+	if (drv && drv->freeze) {
+		ret = drv->freeze(dev);
+		if (ret) {
+			virtio_config_core_enable(dev);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_device_freeze);
+
+int virtio_device_restore(struct virtio_device *dev)
+{
+	return virtio_device_restore_priv(dev, true);
+}
 EXPORT_SYMBOL_GPL(virtio_device_restore);
 #endif
 
+int virtio_device_reset_prepare(struct virtio_device *dev)
+{
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+	int ret;
+
+	if (!drv || !drv->reset_prepare)
+		return -EOPNOTSUPP;
+
+	virtio_config_core_disable(dev);
+
+	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
+
+	ret = drv->reset_prepare(dev);
+	if (ret) {
+		virtio_config_core_enable(dev);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_device_reset_prepare);
+
+int virtio_device_reset_done(struct virtio_device *dev)
+{
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+
+	if (!drv || !drv->reset_done)
+		return -EOPNOTSUPP;
+
+	return virtio_device_restore_priv(dev, false);
+}
+EXPORT_SYMBOL_GPL(virtio_device_reset_done);
+
 static int virtio_init(void)
 {
+	BUILD_BUG_ON(offsetof(struct virtio_device, features) !=
+		     offsetof(struct virtio_device, features_array[0]));
+
 	if (bus_register(&virtio_bus) != 0)
 		panic("virtio bus registration failed");
+	virtio_debug_init();
 	return 0;
 }
 
 static void __exit virtio_exit(void)
 {
+	virtio_debug_exit();
 	bus_unregister(&virtio_bus);
 	ida_destroy(&virtio_index_ida);
 }
 core_initcall(virtio_init);
 module_exit(virtio_exit);
 
+MODULE_DESCRIPTION("Virtio core interface");
 MODULE_LICENSE("GPL");