2019-09-25 12:14:15 +00:00
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// Copyright © 2019 Intel Corporation
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//! The internal VMM API for Cloud Hypervisor.
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//!
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//! This API is a synchronous, [mpsc](https://doc.rust-lang.org/std/sync/mpsc/)
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//! based IPC for sending commands to the VMM thread, from other
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//! Cloud Hypervisor threads. The IPC follows a command-response protocol, i.e.
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//! each command will receive a response back.
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//!
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//! The main Cloud Hypervisor thread creates an API event file descriptor
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//! to notify the VMM thread about pending API commands, together with an
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//! API mpsc channel. The former is the IPC control plane, the latter is the
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//! IPC data plane.
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//! In order to use the IPC, a Cloud Hypervisor thread needs to have a clone
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//! of both the API event file descriptor and the channel Sender. Then it must
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//! go through the following steps:
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//!
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//! 1. The thread creates an mpsc channel for receiving the command response.
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//! 2. The thread sends an ApiRequest to the Sender endpoint. The ApiRequest
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//! contains the response channel Sender, for the VMM API server to be able
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//! to send the response back.
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//! 3. The thread writes to the API event file descriptor to notify the VMM
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//! API server about a pending command.
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//! 4. The thread reads the response back from the VMM API server, from the
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//! response channel Receiver.
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//! 5. The thread handles the response and forwards potential errors.
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2019-09-18 09:14:49 +00:00
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extern crate micro_http;
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pub use self::http::start_http_thread;
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pub mod http;
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2019-09-25 12:14:15 +00:00
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use crate::config::VmConfig;
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use crate::vm::Error;
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use std::sync::mpsc::Sender;
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use std::sync::Arc;
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/// API errors are sent back from the VMM API server through the ApiResponse.
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#[derive(Debug)]
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pub enum ApiError {
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/// The VM could not be created.
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VmCreate(Error),
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/// The VM could not start.
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VmStart(Error),
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}
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pub enum ApiResponsePayload {
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/// No data is sent on the channel.
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Empty,
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}
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/// This is the response sent by the VMM API server through the mpsc channel.
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pub type ApiResponse = std::result::Result<ApiResponsePayload, ApiError>;
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#[allow(clippy::large_enum_variant)]
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pub enum ApiRequest {
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/// Create the virtual machine. This request payload is a VM configuration
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/// (VmConfig).
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/// If the VMM API server could not create the VM, it will send a VmCreate
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/// error back.
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VmCreate(Arc<VmConfig>, Sender<ApiResponse>),
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/// Start the previously created virtual machine.
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/// If the VM was not previously created, the VMM API server will send a
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/// VmStart error back.
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VmStart(Sender<ApiResponse>),
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}
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