1
linux/drivers/virtio/virtio.c
Jason Wang 224de6f886 virtio: allow driver to disable the configure change notification
Sometime, it would be useful to disable the configure change
notification from the driver. So this patch allows this by introducing
a variable config_change_driver_disabled and only allow the configure
change notification callback to be triggered when it is allowed by
both the virtio core and the driver. It is set to false by default to
hold the current semantic so we don't need to change any drivers.

The first user for this would be virtio-net.

Cc: Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com>
Cc: Gia-Khanh Nguyen <gia-khanh.nguyen@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20240814052228.4654-3-jasowang@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-08-15 19:14:19 -07:00

623 lines
15 KiB
C

// 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 < sizeof(dev->features)*8; 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 reset
*
* 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 reset
*
* 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;
u64 driver_features;
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);
/* Figure out what features the driver supports. */
driver_features = 0;
for (i = 0; i < drv->feature_table_size; i++) {
unsigned int f = drv->feature_table[i];
BUG_ON(f >= 64);
driver_features |= (1ULL << 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];
BUG_ON(f >= 64);
driver_features_legacy |= (1ULL << f);
}
} else {
driver_features_legacy = driver_features;
}
if (device_features & (1ULL << VIRTIO_F_VERSION_1))
dev->features = driver_features & device_features;
else
dev->features = driver_features_legacy & device_features;
/* 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))
__virtio_set_bit(dev, i);
err = dev->config->finalize_features(dev);
if (err)
goto err;
if (drv->validate) {
u64 features = dev->features;
err = drv->validate(dev);
if (err)
goto err;
/* Did validation change any features? Then write them again. */
if (features != dev->features) {
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);
}
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,
};
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 suceess, -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_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 */
device_unregister(&dev->dev);
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);
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)
{
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 (drv->restore) {
ret = drv->restore(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;
}
EXPORT_SYMBOL_GPL(virtio_device_restore);
#endif
static int virtio_init(void)
{
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");