virtio net前端
######版本为linux4.13.2#########
virtio_init
bus_register(&virtio_bus)
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,
};
virtio_dev_probe //virtio bus的probe
virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER) //发现virtio驱动
dev->config->set_status(dev, dev->config->get_status(dev) | status);
virtio_finalize_features
virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK) //features ok
drv->probe(dev) //调用驱动的probe，比如virtio net的 virtnet_probe
virtio_device_ready //设置VIRTIO_CONFIG_S_DRIVER_OK
virtio_config_enable //配置使能
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//virtio net前端驱动入口
virtio_net_driver_init
register_virtio_driver(&virtio_net_driver)
driver_register
bus_add_driver
driver_attach //bus_for_each_dev(drv->bus, NULL, drv, __driver_attach)
__driver_attach
driver_probe_device
really_probe
dev->bus->probe(dev) 或 drv->probe //一般bus的probe里会调用drv的probe
省略掉device的probe，这里驱动在注册时也会调用probe（这里最好把device的probe分析下，不然始终没连接起来！）
static struct virtio_driver virtio_net_driver = {
.feature_table = features,
.feature_table_size = ARRAY_SIZE(features),
.feature_table_legacy = features_legacy,
.feature_table_size_legacy = ARRAY_SIZE(features_legacy),
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.validate = virtnet_validate,
.probe = virtnet_probe,
.remove = virtnet_remove,
.config_changed = virtnet_config_changed,
#ifdef CONFIG_PM_SLEEP
.freeze = virtnet_freeze,
.restore = virtnet_restore,
#endif
};
virtnet_probe
dev->netdev_ops = &virtnet_netdev; //此ops回调结构体包含了open、stop、start_xmit、set_mac_address、poll_controller等
dev->ethtool_ops = &virtnet_ethtool_ops; //ethtool的ops
INIT_WORK(&vi->config_work, virtnet_config_changed_work); //配置改变工作队列
init_vqs
virtnet_alloc_queues
INIT_DELAYED_WORK(&vi->refill, refill_work); //后面会用到，用于延时填充avail ring
netif_napi_add //添加virtnet_poll到rq[i].napi
netif_tx_napi_add //添加virtnet_poll_tx到sq[i].napi
sg_init_table
virtnet_find_vqs
callbacks[rxq2vq(i)] = skb_recv_done; //接收回调
callbacks[txq2vq(i)] = skb_xmit_done; //发送回调
vi->vdev->config->find_vqs(XXX,callbacks,XXX) //回调赋值，中断中会调用此回调
//填充avail ring
refill_work
//接收回调
skb_recv_done
virtqueue_napi_schedule
virtnet_poll
//接收处理napi
virtnet_poll
virtnet_poll_cleantx
virtnet_receive
{virtqueue_get_buf
virtqueue_get_buf_ctx //从vring used中取出id、len；从desc_state中取出data？(在virtqueue_add 的时候会进行赋值)
detach_buf //释放相关内存及指针,这里会有num_free++操作(空闲buffer数，已经处理后释放的buffer数)
receive_buf
receive_small[receive_big、receive_mergeable]
build_skb
skb_vnet_hdr
virtio_net_hdr_to_skb
napi_gro_receive //送给上层处理
} //循环处理完所有used ring包
try_fill_recv //条件是：空闲vring数量大于一半；如果失败会启动delaywork
try_fill_recv 添加buffer。主要在receiving路径被调用；也可以在receiving之前的ndo_open中；另一个场景是refill_work（利用napi_disable来关闭receiving）
{add_recvbuf_mergeable
add_recvbuf_big
add_recvbuf_small
virtqueue_add_inbuf
virtqueue_add //添加一个buffer到avail ring
}//循环，每次添加一个，知道把空闲的buffer添加满！
virtqueue_kick //notify
virtqueue_kick_prepare
vring_need_event
return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);//简化后就是event_idx+1>old；而event_idx是记录后端处理位置；意思就是后端处理位置超过（加1后超过，其实是等于）了上次添加buffer的位置，就返回真，需要新添加buffer
//没用event的场景看vring.used->flags判断是否notify
virtqueue_notify
调用其的函数有：
refill_work //用work队列延时填
virtnet_receive《- virtnet_poll《-virtnet_alloc_queues（netif_napi_add）《- virtnet_netpoll（napi_schedule）《-virtnet_netdev.ndo_poll_controller《-netpoll_poll_dev（ops->ndo_poll_controller）//《-netpoll_send_skb_on_dev《-netpoll_send_skb《-netpoll_send_udp（貌似跟丢了,反正是在napi中调用）
调用try_fill_recv条件：if (rq->vq->num_free > virtqueue_get_vring_size(rq->vq) / 2)；vq->num_free为空闲的vring数量（vring_num-avail_num）；即空闲vring数量大于一半时就触发添加。
virtnet_open
virtnet_restore_up
总结：guest中virtio网卡驱动在napi中调用接收函数中判断是否应该添加buffer到vring中。当空闲vring数量大于一半时，会调用try_fill_recv来试图添加buffer，因为还得满足vring_need_event条件；如果try_fill_recv失败会利用schedule_delayed_work来延时再调用。pci中断处理程序中会调用，virtio net注册的回调，进而调用napi来处理接收。
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//发送处理napi
virtnet_poll_tx
//发送回调
skb_xmit_done
=========================
module_pci_driver(virtio_pci_driver)
module_driver(__pci_driver, pci_register_driver, pci_unregister_driver) //驱动注册宏
pci_register_driver
__pci_register_driver
drv->driver.bus = &pci_bus_type;
driver_register
struct bus_type pci_bus_type = {
.name = "pci",
.match = pci_bus_match,
.uevent = pci_uevent,
.probe = pci_device_probe,
.remove = pci_device_remove,
.shutdown = pci_device_shutdown,
.dev_groups = pci_dev_groups,
.bus_groups = pci_bus_groups,
.drv_groups = pci_drv_groups,
.pm = PCI_PM_OPS_PTR,
.num_vf = pci_bus_num_vf,
};
pci_device_probe
__pci_device_probe
pci_call_probe
local_pci_probe
pci_drv->probe //这里会调用virtio_pci_driver的probe(virtio_pci_probe)
//virtio pci驱动入口
virtio_pci_probe
virtio_pci_legacy_probe
vp_dev->ioaddr = pci_iomap(pci_dev, 0, 0) //通过device映射io地址
vp_dev->isr = vp_dev->ioaddr + VIRTIO_PCI_ISR //获取isr中断寄存器地址
vp_dev->vdev.config = &virtio_pci_config_ops //包含vp的set、get、vp_find_vqs等
vp_dev->config_vector = vp_config_vector
vp_dev->setup_vq = setup_vq
[virtio_pci_modern_probe]
register_virtio_device
device_register
vp_find_vqs //config->find_vqs
vp_find_vqs_msix //软中断？
vp_request_msix_vectors
request_irq(XXX,vp_config_changed,XXX) //pci配置改变中断
request_irq(XXX,vp_vring_interrupt,XXX) //pci硬件中断？
vp_setup_vq
vp_dev->setup_vq
request_irq(XXX,vring_interrupt,XXX) //pci硬件中断？
[vp_find_vqs_intx] //常规中断，就一个
request_irq(XXX,vp_interrupt,XXX)
vp_setup_vq
vp_dev->setup_vq
vp_config_vector //设置VIRTIO_MSI_CONFIG_VECTOR寄存器，用来做msi软中断？
setup_vq
vring_create_virtqueue
vring_init
__vring_new_virtqueue
vring_interrupt
more_used //
vq->vq.callback //调用virtqueue的接受或发送回调
vp_config_changed
virtio_config_changed
__virtio_config_changed
drv->config_changed
vp_vring_interrupt
vring_interrupt
vp_interrupt
ioread8(vp_dev->isr) //读清isr
vp_config_changed
vp_vring_interrupt