cloud-hypervisor/docs/vdpa.md

3 vDPA aims at achieving bare-metal performance for devices passed into a virtual
8 the VIRTIO specification on their data-path, while the control path is vendor
11 vDPA framework, being exposed through the vhost interface as a vhost-vdpa
12 device.
14 Because DMA accesses between device and guest are going through virtqueues,
15 migration can be achieved without requiring device's driver to implement any
18 must be done for each and every device's driver.
20 The official [website](https://vdpa-dev.gitlab.io/) contains some extensive
25 `VdpaConfig` (known as `--vdpa` from the CLI perspective) contains the list of
26 parameters available for the vDPA device.
38 --vdpa <vdpa>	vDPA device "path=<device_path>,num_queues=<number_of_queues>,iommu=on|off,id=<device…
43 Path of the vDPA device. Usually `/dev/vhost-vdpa-X`.
52 --vdpa path=/dev/vhost-vdpa-0
57 Number of virtqueues supported by the vDPA device.
66 --vdpa path=/dev/vhost-vdpa-0,num_queues=2
71 Identifier of the vDPA device.
81 --vdpa path=/dev/vhost-vdpa-0,id=vdpa0
86 PCI segment number to which the vDPA device should be attached to.
95 --vdpa path=/dev/vhost-vdpa-0,pci_segment=1
100 The vDPA framework provides a simulator with both `virtio-block` and
101 `virtio-net` implementations. This is very useful for testing vDPA when we
115 `virtio-block` vDPA device:
118 sudo vdpa dev add name vdpa-blk1 mgmtdev vdpasim_blk
119 sudo chown $USER:$USER /dev/vhost-vdpa-0
120 sudo chmod 660 /dev/vhost-vdpa-0
127 ulimit -l unlimited
133 cloud-hypervisor \
134     --cpus boot=1 \
135     --memory size=1G,hugepages=on \
136     --disk path=focal-server-cloudimg-amd64.raw \
137     --kernel vmlinux \
138     --cmdline "root=/dev/vda1 console=hvc0" \
139     --vdpa path=/dev/vhost-vdpa-0,num_queues=1
142 The `virtio-block` device backed by the vDPA simulator can be found as