linux/linux-5.18.11/drivers/virtio/virtio.c

559 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/virtio.h>
#include <linux/spinlock.h>
#include <linux/virtio_config.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 sprintf(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 sprintf(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 sprintf(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 sprintf(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 += sprintf(buf+len, "%c",
__virtio_test_bit(dev, i) ? '1' : '0');
len += sprintf(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, 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(struct device *_dv, struct kobj_uevent_env *env)
{
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_enabled)
dev->config_change_pending = true;
else if (drv && drv->config_changed)
drv->config_changed(dev);
}
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);
static void virtio_config_disable(struct virtio_device *dev)
{
spin_lock_irq(&dev->config_lock);
dev->config_enabled = false;
spin_unlock_irq(&dev->config_lock);
}
static void virtio_config_enable(struct virtio_device *dev)
{
spin_lock_irq(&dev->config_lock);
dev->config_enabled = true;
if (dev->config_change_pending)
__virtio_config_changed(dev);
dev->config_change_pending = false;
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 status;
int ret;
might_sleep();
ret = arch_has_restricted_virtio_memory_access();
if (ret) {
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)
{
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;
/* 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_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_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 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)
{
/* Catch this early. */
BUG_ON(driver->feature_table_size && !driver->feature_table);
driver->driver.bus = &virtio_bus;
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_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
if (err < 0)
goto out;
dev->index = err;
dev_set_name(&dev->dev, "virtio%u", dev->index);
err = virtio_device_of_init(dev);
if (err)
goto out_ida_remove;
spin_lock_init(&dev->config_lock);
dev->config_enabled = false;
dev->config_change_pending = false;
/* 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);
/* Acknowledge that we've seen the device. */
virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
INIT_LIST_HEAD(&dev->vqs);
spin_lock_init(&dev->vqs_list_lock);
/*
* 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_simple_remove(&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);
ida_simple_remove(&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)
{
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);
/* 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;
}
/* Finally, tell the device we're all set */
virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
virtio_config_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");
return 0;
}
static void __exit virtio_exit(void)
{
bus_unregister(&virtio_bus);
ida_destroy(&virtio_index_ida);
}
core_initcall(virtio_init);
module_exit(virtio_exit);
MODULE_LICENSE("GPL");