Intro of QEMU network resource

1. QEMU - network
0416037 李家安

2. VM device
● emulate: security
● front-end & back-end (user space)
● vhost driver
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3. Back End
● User
○ user mode network stack (SLiRP)
○ no ICMP
● TAP: host TAP network
○ tap (vlan mode)
○ bridge
○ socket
○ ...
● VED
● ...
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4. Front End
(Virtual network device)
● e1000
● e1000e
● virtio-net-pci
● vmxnet3
● i82550
● ...
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5. -net
-net nic,model=e1000 -net user -net nic,model=virtio -net tap
● nic: front end
● user: back end
● 802.1q ???
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6. -netdev
-netdev user,id=n1 -device e1000,netdev=n1 -netdev tap,id=n2 -device virtio-net,netdev=n2
● backend onely, bind to device
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7. -nic
-nic tap,model=e1000
● easier & shorter
● on-board NIC
● no hub between NIC and backend
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8. Packet Flow
● tx, rx queue
● eventfd
● ioctl -> /dev/vhost-net device
● register eventfd for the guest
● irqfd
● passing interrupt
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9. Reference
● https://medium.com/@jain.sm/network-packet-flow-in-kvm-qemu-
dc79db719078
● https://www.qemu.org/2018/05/31/nic-parameter/
● https://blog.csdn.net/wangcg123/article/details/77095037
● https://vmsplice.net/~stefan/qemu-kvm-architecture-2015.pdf
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