runtime-rs: add QMP params suppport in cmdline

Fixes: kata-containers#9603

Signed-off-by: Alex Lyn <alex.lyn@antgroup.com>

src/runtime-rs/crates/hypervisor/src/qemu/cmdline_generator.rs

@@ -12,13 +12,16 @@ use std::collections::HashMap;
 use std::fmt::Display;
 use std::fs::{read_to_string, File};
 use std::os::fd::AsRawFd;
+use std::path::PathBuf;
 use tokio;
 
 // These should have been called MiB and GiB for better readability but the
 // more fitting names unfortunately generate linter warnings.
 const MI_B: u64 = 1024 * 1024;
 const GI_B: u64 = 1024 * MI_B;
 
+const QMP_SOCKET_FILE: &str = "qmp.sock";
+
 // The approach taken here is inspired by govmm.  We build structs, each
 // corresponding to a qemu command line parameter, like Kernel, or a device,
 // for instance MemoryBackendFile.  Members of these structs mostly directly
@@ -1178,6 +1181,85 @@ impl ToQemuParams for DeviceIntelIommu {
     }
 }
 
+// Qemu provides methods and types for managing QEMU instances.
+// To manage a qemu instance after it has been launched you need
+// to pass the -qmp option during launch requesting the qemu instance
+// to create a QMP unix domain manageent socket, e.g.,
+// -qmp unix:fd=SOCK_FD,server=on,wait=off.
+// -monitor unix:path=SOCK_PATH,server=on,wait=off.
+#[derive(Debug, Default, PartialEq)]
+pub enum MonitorProtocol {
+    // Socket using a human-friendly text-based protocol.
+    Hmp,
+
+    // Socket using a richer json-based protocol.
+    #[default]
+    Qmp,
+
+    // Same as Qmp with pretty json formatting.
+    QmpPretty,
+}
+
+impl MonitorProtocol {
+    pub fn new(proto: &str) -> Self {
+        match proto {
+            "hmp" => MonitorProtocol::Hmp,
+            "qmp-pretty" => MonitorProtocol::QmpPretty,
+            _ => MonitorProtocol::Qmp,
+        }
+    }
+}
+
+impl ToString for MonitorProtocol {
+    fn to_string(&self) -> String {
+        match *self {
+            MonitorProtocol::Hmp => "monitor".to_string(),
+            MonitorProtocol::QmpPretty => "qmp-pretty".to_string(),
+            _ => "qmp".to_string(),
+        }
+    }
+}
+
+#[derive(Debug)]
+#[allow(dead_code)]
+enum QmpSockType {
+    Fd(File),
+    Path(PathBuf),
+}
+
+#[derive(Debug)]
+#[allow(dead_code)]
+pub struct QmpSocket {
+    // protocol to be used on the socket.
+    protocol: MonitorProtocol,
+    // QMP unix socket to be passed to qemu
+    address: QmpSockType,
+    // server tells if this is a server socket.
+    server: bool,
+    // nowait tells if qemu should block waiting for a client to connect.
+    nowait: bool,
+}
+
+impl QmpSocket {
+    fn new() -> Result<Self> {
+        Ok(QmpSocket {
+            protocol: MonitorProtocol::new("qmp"),
+            address: QmpSockType::Path(QMP_SOCKET_FILE.into()),
+            server: true,
+            nowait: true,
+        })
+    }
+}
+
+#[async_trait]
+impl ToQemuParams for QmpSocket {
+    async fn qemu_params(&self) -> Result<Vec<String>> {
+        let param_qmp = format!("-{}", self.protocol.to_string());
+
+        Ok(vec![param_qmp])
+    }
+}
+
 fn is_running_in_vm() -> Result<bool> {
     let res = read_to_string("/proc/cpuinfo")?
         .lines()
@@ -1212,6 +1294,7 @@ pub struct QemuCmdLine<'a> {
     smp: Smp,
     machine: Machine,
     cpu: Cpu,
+    qmp_socket: QmpSocket,
 
     knobs: Knobs,
 
@@ -1228,6 +1311,7 @@ impl<'a> QemuCmdLine<'a> {
             smp: Smp::new(config),
             machine: Machine::new(config),
             cpu: Cpu::new(config),
+            qmp_socket: QmpSocket::new()?,
             knobs: Knobs::new(config),
             devices: Vec::new(),
         };
@@ -1437,6 +1521,7 @@ impl<'a> QemuCmdLine<'a> {
         result.append(&mut self.machine.qemu_params().await?);
         result.append(&mut self.cpu.qemu_params().await?);
         result.append(&mut self.memory.qemu_params().await?);
+        result.append(&mut self.qmp_socket.qemu_params().await?);
 
         for device in &self.devices {
             result.append(&mut device.qemu_params().await?);