Crates.io | virtio-vsock |
lib.rs | virtio-vsock |
version | 0.8.0 |
source | src |
created_at | 2022-05-19 15:31:53.462507 |
updated_at | 2024-10-21 07:48:07.754888 |
description | virtio vsock device implementation |
homepage | |
repository | https://github.com/rust-vmm/vm-virtio |
max_upload_size | |
id | 589771 |
size | 61,667 |
The virtio-vsock
crate provides abstractions for the components of the
vsock device.
For now, it offers only an implementation for the vsock packet.
The support is provided only for stream sockets.
The vsock device is a socket device that can be used as a communication mechanism between the host and the guest. It is implemented using the virtio standard. The vsock device has three queues: an RX one, a TX one and an event one. In a simplified manner, the communication between the host and the guest is realized with the buffers that are exchanged using the device’s queues. These buffers are called packets in the vsock device context.
The virtio vsock packet is defined in the standard as having a header of type
virtio_vsock_hdr
and an optional data
array of bytes. There are multiple
operations that can be requested within a packet, e.g. VIRTIO_VSOCK_OP_RST
for resetting the connection, VIRTIO_VSOCK_OP_RW
for sending payload. Most
operations are of the VIRTIO_VSOCK_OP_RW
type, which means for data transfer,
and the other ones are used for connection and buffer space management.
data
is non-empty only for the VIRTIO_VSOCK_OP_RW
operations.
The abstraction used for the packet implementation is the VsockPacket
.
It is using
VolatileSlice
s
for representing the header and the data. We chose to use the VolatileSlice
because it's a safe wrapper over the unsafe Rust's raw pointers, and it is also
generic enough to allow creating packets from pointers to slices. Going with a
GuestMemory
based approach would not make such configuration possible.
More details (including design
limitations) in the packet
's module-level documentation.
A VsockPacket
instance is created by parsing a descriptor chain from either
the TX or the RX virtqueue. The VsockPacket
API is also providing methods for
creating/setting up packets directly from pointers to slices.
It also offers setters and getters for each virtio_vsock_hdr
field (e.g.
src_cid, dst_port, op).
The driver queues receive buffers on the RX virtqueue, and outgoing packets on
the TX virtqueue. The device processes the RX virtqueue using
VsockPacket::from_rx_virtq_chain
and fills the buffers with data from the
vsock backend.
On the TX side, the device processes the TX queue using
VsockPacket::from_tx_virtq_chain
, packages the read buffers as vsock packets,
and then sends them to the backend.
Examples of usage can be found as documentation tests in the packet module.
This project is licensed under either of