vmcore/synic.rs
1// Copyright (c) Microsoft Corporation.
2// Licensed under the MIT License.
3
4//! Synic interface definitions used by VmBus.
5
6#![forbid(unsafe_code)]
7#![expect(missing_docs)]
8
9use crate::interrupt::Interrupt;
10use crate::monitor::MonitorId;
11use hvdef::Vtl;
12use inspect::Inspect;
13use std::sync::Arc;
14use std::task::Context;
15use std::task::Poll;
16use std::time::Duration;
17use thiserror::Error;
18
19pub trait MessagePort: Send + Sync {
20 /// Handles a message received on the message port.
21 ///
22 /// A message is `trusted` if it was was received from the guest without using host-visible
23 /// mechanisms on a hardware-isolated VM. The `trusted` parameter is always `false` if not
24 /// running in the paravisor of a hardware-isolated VM.
25 fn poll_handle_message(&self, cx: &mut Context<'_>, msg: &[u8], trusted: bool) -> Poll<()>;
26}
27
28pub trait EventPort: Send + Sync {
29 fn handle_event(&self, flag: u16);
30 fn os_event(&self) -> Option<&pal_event::Event> {
31 None
32 }
33}
34
35#[derive(Debug, Error)]
36#[error("hypervisor error")]
37pub struct HypervisorError(#[from] pub Box<dyn std::error::Error + Send + Sync>);
38
39#[derive(Debug, Error)]
40pub enum Error {
41 #[error("connection ID in use: {0}")]
42 ConnectionIdInUse(u32),
43 #[error(transparent)]
44 Hypervisor(HypervisorError),
45}
46
47/// Trait for accessing partition's synic ports.
48pub trait SynicPortAccess: Send + Sync {
49 /// Adds a host message port, which gets notified when the guest calls
50 /// `HvPostMessage`.
51 fn add_message_port(
52 &self,
53 connection_id: u32,
54 minimum_vtl: Vtl,
55 port: Arc<dyn MessagePort>,
56 ) -> Result<Box<dyn Sync + Send>, Error>;
57
58 /// Adds a host event port, which gets notified when the guest calls
59 /// `HvSignalEvent`.
60 ///
61 /// The `monitor_info` parameter is ignored if the synic does not support MnF.
62 ///
63 /// # Panics
64 ///
65 /// Depending on the implementation, this may panic if the monitor ID indicated in
66 /// `monitor_info` is already in use.
67 fn add_event_port(
68 &self,
69 connection_id: u32,
70 minimum_vtl: Vtl,
71 port: Arc<dyn EventPort>,
72 monitor_info: Option<MonitorInfo>,
73 ) -> Result<Box<dyn Sync + Send>, Error>;
74
75 /// Creates a [`GuestMessagePort`] for posting messages to the guest.
76 fn new_guest_message_port(
77 &self,
78 vtl: Vtl,
79 vp: u32,
80 sint: u8,
81 ) -> Result<Box<dyn GuestMessagePort>, HypervisorError>;
82
83 /// Creates a [`GuestEventPort`] for signaling VMBus channels in the guest.
84 ///
85 /// The `monitor_info` parameter is ignored if the synic does not support outgoing monitored
86 /// interrupts.
87 fn new_guest_event_port(
88 &self,
89 port_id: u32,
90 vtl: Vtl,
91 vp: u32,
92 sint: u8,
93 flag: u16,
94 monitor_info: Option<MonitorInfo>,
95 ) -> Result<Box<dyn GuestEventPort>, HypervisorError>;
96
97 /// Returns whether callers should pass an OS event when creating event
98 /// ports, as opposed to passing a function to call.
99 ///
100 /// This is true when the hypervisor can more quickly dispatch an OS event
101 /// and resume the VP than it can take an intercept into user mode and call
102 /// a function.
103 fn prefer_os_events(&self) -> bool;
104
105 /// Returns an object for manipulating the monitor page, or None if monitor pages aren't
106 /// supported.
107 fn monitor_support(&self) -> Option<&dyn SynicMonitorAccess> {
108 None
109 }
110}
111
112/// Provides monitor page functionality for a `SynicPortAccess` implementation.
113pub trait SynicMonitorAccess: SynicPortAccess {
114 /// Sets the GPA of the monitor page currently in use.
115 fn set_monitor_page(&self, vtl: Vtl, gpa: Option<MonitorPageGpas>) -> anyhow::Result<()>;
116}
117
118/// A guest event port, created by [`SynicPortAccess::new_guest_event_port`].
119pub trait GuestEventPort: Send + Sync {
120 /// Returns an interrupt object used to signal the guest.
121 fn interrupt(&self) -> Interrupt;
122
123 /// Updates the target VP for the event port.
124 fn set_target_vp(&mut self, vp: u32) -> Result<(), HypervisorError>;
125}
126
127/// A guest message port, created by [`SynicPortAccess::new_guest_message_port`].
128pub trait GuestMessagePort: Send + Sync + Inspect {
129 /// Posts a message to the guest.
130 ///
131 /// It is the caller's responsibility to not queue too many messages. Not all transport layers
132 /// are guaranteed to support backpressure.
133 fn poll_post_message(&mut self, cx: &mut Context<'_>, typ: u32, payload: &[u8]) -> Poll<()>;
134
135 /// Changes the virtual processor to which messages are sent.
136 fn set_target_vp(&mut self, vp: u32) -> Result<(), HypervisorError>;
137}
138
139/// Represents the GPA of the outgoing and incoming monitor pages.
140#[derive(Clone, Copy, PartialEq, Eq, Debug, Default, Inspect)]
141pub struct MonitorPageGpas {
142 /// The GPA of the incoming monitor page.
143 #[inspect(hex)]
144 pub parent_to_child: u64,
145 /// The GPA of the outgoing monitor page.
146 #[inspect(hex)]
147 pub child_to_parent: u64,
148}
149
150/// Provides information about monitor usage for a synic event port.
151#[derive(Clone, Copy, Debug, PartialEq, Eq)]
152pub struct MonitorInfo {
153 // The monitor ID used by the port.
154 pub monitor_id: MonitorId,
155 /// The nterrupt latency.
156 pub latency: Duration,
157}