Virtio interface
This attempts to implement a "virtual I/O" layer which should allow common drivers to be efficiently used across most virtual I/O mechanisms. It will no-doubt need further enhancement. The virtio drivers add buffers to virtio queues; as the buffers are consumed the driver "interrupt" callbacks are invoked. There is also a generic implementation of config space which drivers can query to get setup information from the host. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Dor Laor <dor.laor@qumranet.com> Cc: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Rusty Russell
parent
47436aa4ad
commit
ec3d41c4db
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@ -93,4 +93,6 @@ source "drivers/auxdisplay/Kconfig"
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source "drivers/kvm/Kconfig"
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source "drivers/uio/Kconfig"
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source "drivers/virtio/Kconfig"
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endmenu
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@ -91,3 +91,4 @@ obj-$(CONFIG_HID) += hid/
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obj-$(CONFIG_PPC_PS3) += ps3/
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obj-$(CONFIG_OF) += of/
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obj-$(CONFIG_SSB) += ssb/
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obj-$(CONFIG_VIRTIO) += virtio/
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@ -0,0 +1,3 @@
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# Virtio always gets selected by whoever wants it.
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config VIRTIO
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bool
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@ -0,0 +1 @@
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obj-$(CONFIG_VIRTIO) += virtio.o
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@ -0,0 +1,13 @@
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/* Configuration space parsing helpers for virtio.
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*
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* The configuration is [type][len][... len bytes ...] fields.
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*
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* Copyright 2007 Rusty Russell, IBM Corporation.
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* GPL v2 or later.
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*/
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#include <linux/err.h>
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#include <linux/virtio.h>
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#include <linux/virtio_config.h>
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#include <linux/bug.h>
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#include <asm/system.h>
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@ -0,0 +1,171 @@
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#include <linux/virtio.h>
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#include <linux/spinlock.h>
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#include <linux/virtio_config.h>
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static ssize_t device_show(struct device *_d,
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struct device_attribute *attr, char *buf)
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{
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struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
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return sprintf(buf, "%hu", dev->id.device);
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}
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static ssize_t vendor_show(struct device *_d,
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struct device_attribute *attr, char *buf)
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{
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struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
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return sprintf(buf, "%hu", dev->id.vendor);
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}
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static ssize_t status_show(struct device *_d,
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struct device_attribute *attr, char *buf)
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{
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struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
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return sprintf(buf, "0x%08x", dev->config->get_status(dev));
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}
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static struct device_attribute virtio_dev_attrs[] = {
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__ATTR_RO(device),
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__ATTR_RO(vendor),
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__ATTR_RO(status),
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__ATTR_NULL
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};
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static inline int virtio_id_match(const struct virtio_device *dev,
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const struct virtio_device_id *id)
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{
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if (id->device != dev->id.device)
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return 0;
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return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor != dev->id.vendor;
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}
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/* This looks through all the IDs a driver claims to support. If any of them
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* match, we return 1 and the kernel will call virtio_dev_probe(). */
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static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
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{
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unsigned int i;
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struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
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const struct virtio_device_id *ids;
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ids = container_of(_dr, struct virtio_driver, driver)->id_table;
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for (i = 0; ids[i].device; i++)
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if (virtio_id_match(dev, &ids[i]))
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return 1;
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return 0;
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}
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static struct bus_type virtio_bus = {
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.name = "virtio",
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.match = virtio_dev_match,
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.dev_attrs = virtio_dev_attrs,
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};
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static void add_status(struct virtio_device *dev, unsigned status)
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{
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dev->config->set_status(dev, dev->config->get_status(dev) | status);
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}
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static int virtio_dev_probe(struct device *_d)
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{
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int err;
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struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
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struct virtio_driver *drv = container_of(dev->dev.driver,
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struct virtio_driver, driver);
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add_status(dev, VIRTIO_CONFIG_S_DRIVER);
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err = drv->probe(dev);
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if (err)
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add_status(dev, VIRTIO_CONFIG_S_FAILED);
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else
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add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
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return err;
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}
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int register_virtio_driver(struct virtio_driver *driver)
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{
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driver->driver.bus = &virtio_bus;
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driver->driver.probe = virtio_dev_probe;
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return driver_register(&driver->driver);
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}
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EXPORT_SYMBOL_GPL(register_virtio_driver);
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void unregister_virtio_driver(struct virtio_driver *driver)
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{
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driver_unregister(&driver->driver);
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}
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EXPORT_SYMBOL_GPL(unregister_virtio_driver);
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int register_virtio_device(struct virtio_device *dev)
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{
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int err;
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dev->dev.bus = &virtio_bus;
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sprintf(dev->dev.bus_id, "%u", dev->index);
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/* Acknowledge that we've seen the device. */
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add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
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/* device_register() causes the bus infrastructure to look for a
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* matching driver. */
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err = device_register(&dev->dev);
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if (err)
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add_status(dev, VIRTIO_CONFIG_S_FAILED);
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return err;
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}
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EXPORT_SYMBOL_GPL(register_virtio_device);
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void unregister_virtio_device(struct virtio_device *dev)
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{
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device_unregister(&dev->dev);
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}
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EXPORT_SYMBOL_GPL(unregister_virtio_device);
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int __virtio_config_val(struct virtio_device *vdev,
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u8 type, void *val, size_t size)
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{
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void *token;
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unsigned int len;
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token = vdev->config->find(vdev, type, &len);
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if (!token)
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return -ENOENT;
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if (len != size)
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return -EIO;
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vdev->config->get(vdev, token, val, size);
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return 0;
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}
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EXPORT_SYMBOL_GPL(__virtio_config_val);
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int virtio_use_bit(struct virtio_device *vdev,
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void *token, unsigned int len, unsigned int bitnum)
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{
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unsigned long bits[16];
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/* This makes it convenient to pass-through find() results. */
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if (!token)
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return 0;
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/* bit not in range of this bitfield? */
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if (bitnum * 8 >= len / 2)
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return 0;
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/* Giant feature bitfields are silly. */
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BUG_ON(len > sizeof(bits));
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vdev->config->get(vdev, token, bits, len);
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if (!test_bit(bitnum, bits))
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return 0;
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/* Set acknowledge bit, and write it back. */
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set_bit(bitnum + len * 8 / 2, bits);
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vdev->config->set(vdev, token, bits, len);
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return 1;
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}
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EXPORT_SYMBOL_GPL(virtio_use_bit);
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static int virtio_init(void)
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{
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if (bus_register(&virtio_bus) != 0)
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panic("virtio bus registration failed");
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return 0;
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}
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core_initcall(virtio_init);
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@ -343,6 +343,7 @@ unifdef-y += user.h
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unifdef-y += utsname.h
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unifdef-y += videodev2.h
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unifdef-y += videodev.h
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unifdef-y += virtio_config.h
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unifdef-y += wait.h
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unifdef-y += wanrouter.h
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unifdef-y += watchdog.h
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@ -361,4 +361,10 @@ struct ssb_device_id {
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#define SSB_ANY_ID 0xFFFF
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#define SSB_ANY_REV 0xFF
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struct virtio_device_id {
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__u32 device;
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__u32 vendor;
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};
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#define VIRTIO_DEV_ANY_ID 0xffffffff
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#endif /* LINUX_MOD_DEVICETABLE_H */
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@ -0,0 +1,110 @@
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#ifndef _LINUX_VIRTIO_H
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#define _LINUX_VIRTIO_H
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/* Everything a virtio driver needs to work with any particular virtio
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* implementation. */
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#include <linux/types.h>
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#include <linux/scatterlist.h>
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#include <linux/spinlock.h>
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#include <linux/device.h>
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#include <linux/mod_devicetable.h>
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/**
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* virtqueue - a queue to register buffers for sending or receiving.
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* @callback: the function to call when buffers are consumed (can be NULL).
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* If this returns false, callbacks are suppressed until vq_ops->restart
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* is called.
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* @vdev: the virtio device this queue was created for.
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* @vq_ops: the operations for this virtqueue (see below).
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* @priv: a pointer for the virtqueue implementation to use.
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*/
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struct virtqueue
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{
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bool (*callback)(struct virtqueue *vq);
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struct virtio_device *vdev;
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struct virtqueue_ops *vq_ops;
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void *priv;
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};
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/**
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* virtqueue_ops - operations for virtqueue abstraction layer
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* @add_buf: expose buffer to other end
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* vq: the struct virtqueue we're talking about.
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* sg: the description of the buffer(s).
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* out_num: the number of sg readable by other side
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* in_num: the number of sg which are writable (after readable ones)
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* data: the token identifying the buffer.
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* Returns 0 or an error.
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* @kick: update after add_buf
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* vq: the struct virtqueue
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* After one or more add_buf calls, invoke this to kick the other side.
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* @get_buf: get the next used buffer
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* vq: the struct virtqueue we're talking about.
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* len: the length written into the buffer
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* Returns NULL or the "data" token handed to add_buf.
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* @restart: restart callbacks after callback returned false.
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* vq: the struct virtqueue we're talking about.
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* This returns "false" (and doesn't re-enable) if there are pending
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* buffers in the queue, to avoid a race.
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* @shutdown: "unadd" all buffers.
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* vq: the struct virtqueue we're talking about.
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* Remove everything from the queue.
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*
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* Locking rules are straightforward: the driver is responsible for
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* locking. No two operations may be invoked simultaneously.
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*
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* All operations can be called in any context.
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*/
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struct virtqueue_ops {
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int (*add_buf)(struct virtqueue *vq,
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struct scatterlist sg[],
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unsigned int out_num,
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unsigned int in_num,
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void *data);
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void (*kick)(struct virtqueue *vq);
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void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
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bool (*restart)(struct virtqueue *vq);
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void (*shutdown)(struct virtqueue *vq);
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};
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/**
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* virtio_device - representation of a device using virtio
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* @index: unique position on the virtio bus
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* @dev: underlying device.
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* @id: the device type identification (used to match it with a driver).
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* @config: the configuration ops for this device.
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* @priv: private pointer for the driver's use.
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*/
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struct virtio_device
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{
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int index;
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struct device dev;
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struct virtio_device_id id;
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struct virtio_config_ops *config;
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void *priv;
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};
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int register_virtio_device(struct virtio_device *dev);
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void unregister_virtio_device(struct virtio_device *dev);
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/**
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* virtio_driver - operations for a virtio I/O driver
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* @driver: underlying device driver (populate name and owner).
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* @id_table: the ids serviced by this driver.
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* @probe: the function to call when a device is found. Returns a token for
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* remove, or PTR_ERR().
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* @remove: the function when a device is removed.
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*/
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struct virtio_driver {
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struct device_driver driver;
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const struct virtio_device_id *id_table;
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int (*probe)(struct virtio_device *dev);
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void (*remove)(struct virtio_device *dev);
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};
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int register_virtio_driver(struct virtio_driver *drv);
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void unregister_virtio_driver(struct virtio_driver *drv);
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#endif /* _LINUX_VIRTIO_H */
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@ -0,0 +1,111 @@
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#ifndef _LINUX_VIRTIO_CONFIG_H
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#define _LINUX_VIRTIO_CONFIG_H
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/* Virtio devices use a standardized configuration space to define their
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* features and pass configuration information, but each implementation can
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* store and access that space differently. */
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#include <linux/types.h>
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/* Status byte for guest to report progress, and synchronize config. */
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/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
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#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
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/* We have found a driver for the device. */
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#define VIRTIO_CONFIG_S_DRIVER 2
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/* Driver has used its parts of the config, and is happy */
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#define VIRTIO_CONFIG_S_DRIVER_OK 4
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/* We've given up on this device. */
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#define VIRTIO_CONFIG_S_FAILED 0x80
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/* Feature byte (actually 7 bits availabe): */
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/* Requirements/features of the virtio implementation. */
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#define VIRTIO_CONFIG_F_VIRTIO 1
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/* Requirements/features of the virtqueue (may have more than one). */
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#define VIRTIO_CONFIG_F_VIRTQUEUE 2
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#ifdef __KERNEL__
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struct virtio_device;
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/**
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* virtio_config_ops - operations for configuring a virtio device
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* @find: search for the next configuration field of the given type.
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* vdev: the virtio_device
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* type: the feature type
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* len: the (returned) length of the field if found.
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* Returns a token if found, or NULL. Never returnes the same field twice
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* (ie. it's used up).
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* @get: read the value of a configuration field after find().
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* vdev: the virtio_device
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* token: the token returned from find().
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* buf: the buffer to write the field value into.
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* len: the length of the buffer (given by find()).
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* Note that contents are conventionally little-endian.
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* @set: write the value of a configuration field after find().
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* vdev: the virtio_device
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* token: the token returned from find().
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* buf: the buffer to read the field value from.
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* len: the length of the buffer (given by find()).
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* Note that contents are conventionally little-endian.
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* @get_status: read the status byte
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* vdev: the virtio_device
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* Returns the status byte
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* @set_status: write the status byte
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* vdev: the virtio_device
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* status: the new status byte
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* @find_vq: find the first VIRTIO_CONFIG_F_VIRTQUEUE and create a virtqueue.
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* vdev: the virtio_device
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* callback: the virqtueue callback
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* Returns the new virtqueue or ERR_PTR().
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* @del_vq: free a virtqueue found by find_vq().
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*/
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struct virtio_config_ops
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{
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void *(*find)(struct virtio_device *vdev, u8 type, unsigned *len);
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void (*get)(struct virtio_device *vdev, void *token,
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void *buf, unsigned len);
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void (*set)(struct virtio_device *vdev, void *token,
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const void *buf, unsigned len);
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u8 (*get_status)(struct virtio_device *vdev);
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void (*set_status)(struct virtio_device *vdev, u8 status);
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struct virtqueue *(*find_vq)(struct virtio_device *vdev,
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bool (*callback)(struct virtqueue *));
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void (*del_vq)(struct virtqueue *vq);
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};
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/**
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* virtio_config_val - get a single virtio config and mark it used.
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* @config: the virtio config space
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* @type: the type to search for.
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* @val: a pointer to the value to fill in.
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*
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* Once used, the config type is marked with VIRTIO_CONFIG_F_USED so it can't
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* be found again. This version does endian conversion. */
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#define virtio_config_val(vdev, type, v) ({ \
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int _err = __virtio_config_val((vdev),(type),(v),sizeof(*(v))); \
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\
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BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
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&& sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
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if (!_err) { \
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switch (sizeof(*(v))) { \
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case 2: le16_to_cpus((__u16 *) v); break; \
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case 4: le32_to_cpus((__u32 *) v); break; \
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case 8: le64_to_cpus((__u64 *) v); break; \
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} \
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} \
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_err; \
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})
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int __virtio_config_val(struct virtio_device *dev,
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u8 type, void *val, size_t size);
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/**
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* virtio_use_bit - helper to use a feature bit in a bitfield value.
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* @dev: the virtio device
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* @token: the token as returned from vdev->config->find().
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* @len: the length of the field.
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* @bitnum: the bit to test.
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*
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* If handed a NULL token, it returns false, otherwise returns bit status.
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* If it's one, it sets the mirroring acknowledgement bit. */
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int virtio_use_bit(struct virtio_device *vdev,
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void *token, unsigned int len, unsigned int bitnum);
|
||||
#endif /* __KERNEL__ */
|
||||
#endif /* _LINUX_VIRTIO_CONFIG_H */
|
||||
Reference in New Issue