Merge remote-tracking branch 'aosp/upstream-main' into mergeupstream

Re-ran cargo2android.py.

Bug: 193402941
Bug: 192256642
Test: atest VirtualizationTestCases
Change-Id: I7ac0c23ff7d700e45e7527db3d226aa644186cd0
tree: aa9ce57a4fe4e6e24aab95a0c2b087d171aafae0
  1. .buildkite/
  2. .cargo/
  3. .github/
  4. docs/
  5. src/
  6. .gitignore
  7. .gitmodules
  8. Android.bp
  9. Cargo.toml
  10. CODEOWNERS
  11. coverage_config_aarch64.json
  12. coverage_config_x86_64.json
  13. LICENSE
  14. LICENSE-BSD-3-Clause
  15. LICENSE-BSD-Chromium
  16. METADATA
  17. MODULE_LICENSE_APACHE2
  18. OWNERS
  19. PRESUBMIT.cfg
  20. README.md
README.md

vHost

A pure rust library for vDPA, vhost and vhost-user.

The vhost crate aims to help implementing dataplane for virtio backend drivers. It supports three different types of dataplane drivers:

  • vhost: the dataplane is implemented by linux kernel
  • vhost-user: the dataplane is implemented by dedicated vhost-user servers
  • vDPA(vhost DataPath Accelerator): the dataplane is implemented by hardwares

The main relationship among Traits and Structs exported by the vhost crate is as below:

vhost Architecture

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 aims 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.