3e99098bf3
The previous definitions does not cover config space read/write
and only cover general message as below:
A vhost-user message consists of 3 header fields and a payload.
+---------+-------+------+---------+
| request | flags | size | payload |
+---------+-------+------+---------+
but for config space, the payload include:
Virtio device config space
^^^^^^^^^^^^^^^^^^^^^^^^^^
+--------+------+-------+---------+
| offset | size | flags | payload |
+--------+------+-------+---------+
:offset: a 32-bit offset of virtio device's configuration space
:size: a 32-bit configuration space access size in bytes
🎏 a 32-bit value:
- 0: Vhost master messages used for writeable fields
- 1: Vhost master messages used for live migration
:payload: Size bytes array holding the contents of the virtio
device's configuration space
This patch add specific functions for config message, which can
get/set config space from/to backend.
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
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| Cargo.toml | ||
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| LICENSE-MIT | ||
| README.md | ||
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.