Clone this repo:
  1. 6ccc681 vhost-user: enlarge supported number of vrings by Liu Jiang · 2 months ago main
  2. fec8460 vhost-kern: fix a typo by Liu Jiang · 2 months ago
  3. a687687 vhost-kern: upgrade to latest vm-memory crate by Liu Jiang · 2 months ago
  4. ce094b2 vhost-kern: treat addrs in VringConfigData as HVA by Liu Jiang · 2 months ago
  5. d257479 fix link issues on aarch64 musl by Andreea Florescu · 6 months ago

vHost

A crate to support vhost backend drivers for virtio devices.

Kernel-based vHost Backend Drivers

The vhost drivers in Linux provide in-kernel virtio device emulation. Normally the hypervisor userspace process emulates I/O accesses from the guest. Vhost puts virtio emulation code into the kernel, taking hypervisor userspace out of the picture. This allows device emulation code to directly call into kernel subsystems instead of performing system calls from userspace. The hypervisor relies on ioctl based interfaces to control those in-kernel vhost drivers, such as vhost-net, vhost-scsi and vhost-vsock etc.

vHost-user Backend Drivers

The vhost-user protocol is aiming to implement vhost backend drivers in userspace, which complements the ioctl interface used to control the vhost implementation in the Linux kernel. It implements the control plane needed to establish virtqueue sharing with a user space process on the same host. It uses communication over a Unix domain socket to share file descriptors in the ancillary data of the message.

The protocol defines two sides of the communication, master and slave. Master is the application that shares its virtqueues, slave is the consumer of the virtqueues. Master and slave can be either a client (i.e. connecting) or server (listening) in the socket communication.