Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 752 insertions, 0 deletions

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
new file mode 100644
index 000000000..b6c9e927b
--- /dev/null
+++ b/drivers/virtio/virtio.c
@@ -0,0 +1,752 @@
+// 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. */
+static DEFINE_IDA(virtio_index_ida);
+
+static ssize_t device_show(struct device *_d,
+			   struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sysfs_emit(buf, "0x%04x\n", dev->id.device);
+}
+static DEVICE_ATTR_RO(device);
+
+static ssize_t vendor_show(struct device *_d,
+			   struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sysfs_emit(buf, "0x%04x\n", dev->id.vendor);
+}
+static DEVICE_ATTR_RO(vendor);
+
+static ssize_t status_show(struct device *_d,
+			   struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sysfs_emit(buf, "0x%08x\n", dev->config->get_status(dev));
+}
+static DEVICE_ATTR_RO(status);
+
+static ssize_t modalias_show(struct device *_d,
+			     struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sysfs_emit(buf, "virtio:d%08Xv%08X\n",
+		       dev->id.device, dev->id.vendor);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static ssize_t features_show(struct device *_d,
+			     struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	unsigned int i;
+	ssize_t len = 0;
+
+	/* We actually represent this as a bitstring, as it could be
+	 * arbitrary length in future. */
+	for (i = 0; i < VIRTIO_FEATURES_BITS; i++)
+		len += sysfs_emit_at(buf, len, "%c",
+			       __virtio_test_bit(dev, i) ? '1' : '0');
+	len += sysfs_emit_at(buf, len, "\n");
+	return len;
+}
+static DEVICE_ATTR_RO(features);
+
+static struct attribute *virtio_dev_attrs[] = {
+	&dev_attr_device.attr,
+	&dev_attr_vendor.attr,
+	&dev_attr_status.attr,
+	&dev_attr_modalias.attr,
+	&dev_attr_features.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(virtio_dev);
+
+static inline int virtio_id_match(const struct virtio_device *dev,
+				  const struct virtio_device_id *id)
+{
+	if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
+		return 0;
+
+	return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
+}
+
+/* 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, const struct device_driver *_dr)
+{
+	unsigned int i;
+	struct virtio_device *dev = dev_to_virtio(_dv);
+	const struct virtio_device_id *ids;
+
+	ids = drv_to_virtio(_dr)->id_table;
+	for (i = 0; ids[i].device; i++)
+		if (virtio_id_match(dev, &ids[i]))
+			return 1;
+	return 0;
+}
+
+static int virtio_uevent(const struct device *_dv, struct kobj_uevent_env *env)
+{
+	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);
+}
+
+void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
+					 unsigned int fbit)
+{
+	unsigned int i;
+	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
+
+	for (i = 0; i < drv->feature_table_size; i++)
+		if (drv->feature_table[i] == fbit)
+			return;
+
+	if (drv->feature_table_legacy) {
+		for (i = 0; i < drv->feature_table_size_legacy; i++)
+			if (drv->feature_table_legacy[i] == fbit)
+				return;
+	}
+
+	BUG();
+}
+EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
+
+static void __virtio_config_changed(struct virtio_device *dev)
+{
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+
+	if (!dev->config_core_enabled || dev->config_driver_disabled)
+		dev->config_change_pending = true;
+	else if (drv && drv->config_changed) {
+		drv->config_changed(dev);
+		dev->config_change_pending = false;
+	}
+}
+
+void virtio_config_changed(struct virtio_device *dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->config_lock, flags);
+	__virtio_config_changed(dev);
+	spin_unlock_irqrestore(&dev->config_lock, flags);
+}
+EXPORT_SYMBOL_GPL(virtio_config_changed);
+
+/**
+ * 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_driver_disabled = true;
+	spin_unlock_irq(&dev->config_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_config_driver_disable);
+
+/**
+ * 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_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);
+	spin_unlock_irq(&dev->config_lock);
+}
+
+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);
+
+/* Do some validation, then set FEATURES_OK */
+static int virtio_features_ok(struct virtio_device *dev)
+{
+	unsigned int status;
+
+	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;
+
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
+	status = dev->config->get_status(dev);
+	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
+		dev_err(&dev->dev, "virtio: device refuses features: %x\n",
+			status);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+/**
+ * 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[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. */
+	virtio_get_features(dev, device_features);
+
+	/* Figure out what features the driver supports. */
+	virtio_features_zero(driver_features);
+	for (i = 0; i < drv->feature_table_size; i++) {
+		unsigned int f = drv->feature_table[i];
+		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 */
+	if (drv->feature_table_legacy) {
+		driver_features_legacy = 0;
+		for (i = 0; i < drv->feature_table_size_legacy; i++) {
+			unsigned int f = drv->feature_table_legacy[i];
+			if (!WARN_ON_ONCE(f >= 64))
+				driver_features_legacy |= (1ULL << f);
+		}
+	} else {
+		driver_features_legacy = driver_features[0];
+	}
+
+	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 (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_features_ok(dev);
+	if (err)
+		goto err;
+
+	err = drv->probe(dev);
+	if (err)
+		goto err;
+
+	/* If probe didn't do it, mark device DRIVER_OK ourselves. */
+	if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
+		virtio_device_ready(dev);
+
+	if (drv->scan)
+		drv->scan(dev);
+
+	virtio_config_core_enable(dev);
+
+	return 0;
+
+err:
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	return err;
+
+}
+
+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_core_disable(dev);
+
+	drv->remove(dev);
+
+	/* Driver should have reset device. */
+	WARN_ON_ONCE(dev->config->get_status(dev));
+
+	/* Acknowledge the device's existence again. */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+	of_node_put(dev->dev.of_node);
+}
+
+/*
+ * 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);
+}
+
+/**
+ * virtio_device_shutdown - break and reset a device on shutdown
+ * @dev: the device
+ *
+ * Drivers with their own .shutdown method should quiesce their activity and
+ * then call this to stop the device the way the generic shutdown path does.
+ */
+void virtio_device_shutdown(struct virtio_device *dev)
+{
+	/*
+	 * 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);
+}
+EXPORT_SYMBOL_GPL(virtio_device_shutdown);
+
+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;
+	}
+
+	virtio_device_shutdown(dev);
+}
+
+static int virtio_dev_num_vf(struct device *dev)
+{
+	struct virtio_device *vdev = dev_to_virtio(dev);
+
+	return dev_num_vf(vdev->dev.parent);
+}
+
+
+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,
+	.num_vf = virtio_dev_num_vf,
+};
+
+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);
+
+void unregister_virtio_driver(struct virtio_driver *driver)
+{
+	driver_unregister(&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
+ *
+ * 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 success, -error on failure
+ */
+int register_virtio_device(struct virtio_device *dev)
+{
+	int err;
+
+	dev->dev.bus = &virtio_bus;
+	device_initialize(&dev->dev);
+
+	/* Assign a unique device index and hence name. */
+	err = ida_alloc(&virtio_index_ida, GFP_KERNEL);
+	if (err < 0)
+		goto out;
+
+	dev->index = err;
+	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_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. */
+	virtio_reset_device(dev);
+
+	/* Acknowledge that we've seen the device. */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+	virtio_debug_device_init(dev);
+
+	/*
+	 * device_add() causes the bus infrastructure to look for a matching
+	 * driver.
+	 */
+	err = device_add(&dev->dev);
+	if (err)
+		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:
+	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 */
+
+	virtio_debug_device_exit(dev);
+	device_unregister(&dev->dev);
+	ida_free(&virtio_index_ida, index);
+}
+EXPORT_SYMBOL_GPL(unregister_virtio_device);
+
+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. */
+	virtio_reset_device(dev);
+
+	/* Acknowledge that we've seen the device. */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+	/* Maybe driver failed before freeze.
+	 * Restore the failed status, for debugging. */
+	if (dev->failed)
+		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+
+	if (!drv)
+		return 0;
+
+	/* We have a driver! */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
+
+	ret = dev->config->finalize_features(dev);
+	if (ret)
+		goto err;
+
+	ret = virtio_features_ok(dev);
+	if (ret)
+		goto err;
+
+	if (restore) {
+		if (drv->restore) {
+			ret = drv->restore(dev);
+			if (ret)
+				goto err;
+		}
+	} else {
+		ret = drv->reset_done(dev);
+		if (ret)
+			goto err;
+	}
+
+	/* 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_core_enable(dev);
+
+	return 0;
+
+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");