hotplug: add room for future acpi hotplug mechanism

In order to support ACPI hotplug in the future with the cooperative work
from the Kata community, we add ACPI feature and dbs-upcall feature to
add room for ACPI hotplug.

Signed-off-by: Chao Wu <chaowu@linux.alibaba.com>

src/dragonball/Cargo.toml

@@ -45,8 +45,9 @@ slog-term = "2.9.0"
 slog-async = "2.7.0"
 
 [features]
+acpi = []
 atomic-guest-memory = []
-hotplug = ["dbs-upcall", "virtio-vsock"]
+hotplug = ["virtio-vsock"]
 virtio-vsock = ["dbs-virtio-devices/virtio-vsock", "virtio-queue"]
 
 [patch.'crates-io']

src/dragonball/src/device_manager/mod.rs

@@ -29,10 +29,10 @@ use dbs_virtio_devices::{
     VirtioDevice,
 };
 
-#[cfg(feature = "hotplug")]
+#[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
 use dbs_upcall::{
-    MmioDevRequest, DevMgrRequest, DevMgrService, UpcallClient, UpcallClientError,
-    UpcallClientRequest, UpcallClientResponse
+    DevMgrRequest, DevMgrService, MmioDevRequest, UpcallClient, UpcallClientError,
+    UpcallClientRequest, UpcallClientResponse,
 };
 
 use crate::address_space_manager::GuestAddressSpaceImpl;
@@ -90,7 +90,7 @@ pub enum DeviceMgrError {
     #[error(transparent)]
     Virtio(virtio::Error),
 
-    #[cfg(feature = "hotplug")]
+    #[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
     /// Failed to hotplug the device.
     #[error("failed to hotplug virtual device")]
     HotplugDevice(#[source] UpcallClientError),
@@ -199,7 +199,7 @@ pub struct DeviceOpContext {
     logger: slog::Logger,
     is_hotplug: bool,
 
-    #[cfg(feature = "hotplug")]
+    #[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
     upcall_client: Option<Arc<UpcallClient<DevMgrService>>>,
     #[cfg(feature = "dbs-virtio-devices")]
     virtio_devices: Vec<Arc<DbsMmioV2Device>>,
@@ -233,7 +233,7 @@ impl DeviceOpContext {
             address_space,
             logger,
             is_hotplug,
-            #[cfg(feature = "hotplug")]
+            #[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
             upcall_client: None,
             #[cfg(feature = "dbs-virtio-devices")]
             virtio_devices: Vec::new(),
@@ -301,7 +301,7 @@ impl DeviceOpContext {
     }
 }
 
-#[cfg(feature = "hotplug")]
+#[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
 impl DeviceOpContext {
     fn call_hotplug_device(
         &self,
@@ -362,6 +362,11 @@ impl DeviceOpContext {
     }
 }
 
+#[cfg(all(feature = "hotplug", feature = "acpi"))]
+impl DeviceOpContext {
+    // TODO: We will implement this when we develop ACPI virtualization
+}
+
 /// Device manager for virtual machines, which manages all device for a virtual machine.
 pub struct DeviceManager {
     io_manager: Arc<ArcSwap<IoManager>>,

src/dragonball/src/vcpu/vcpu_manager.rs

@@ -15,7 +15,7 @@ use std::sync::mpsc::{channel, Receiver, RecvError, RecvTimeoutError, Sender};
 use std::sync::{Arc, Barrier, Mutex, RwLock};
 use std::time::Duration;
 
-#[cfg(feature = "hotplug")]
+#[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
 use dbs_upcall::{DevMgrService, UpcallClient};
 use dbs_utils::epoll_manager::{EpollManager, EventOps, EventSet, Events, MutEventSubscriber};
 use dbs_utils::time::TimestampUs;
@@ -206,7 +206,7 @@ pub struct VcpuManager {
     vcpus_in_action: (VcpuAction, Vec<u8>),
     pub(crate) reset_event_fd: Option<EventFd>,
 
-    #[cfg(feature = "hotplug")]
+    #[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
     upcall_channel: Option<Arc<UpcallClient<DevMgrService>>>,
 
     // X86 specific fields.
@@ -290,7 +290,7 @@ impl VcpuManager {
             action_sycn_tx: None,
             vcpus_in_action: (VcpuAction::None, Vec::new()),
             reset_event_fd: None,
-            #[cfg(feature = "hotplug")]
+            #[cfg(all(feature = "hotplug", feature = "dbs-upcall"))]
             upcall_channel: None,
             #[cfg(target_arch = "x86_64")]
             supported_cpuid,
@@ -794,6 +794,7 @@ mod hotplug {
     #[cfg(all(target_arch = "aarch64", not(test)))]
     const APIC_VERSION: u8 = 0;
 
+    #[cfg(feature = "dbs-upcall")]
     impl VcpuManager {
         /// add upcall channel for vcpu manager
         pub fn set_upcall_channel(