vmm: api: Add developer preview warning for device hot-plugging

Use log_dev_preview_warning() to warn the user about hot-plugging and
unplugging being in developer preview and that it's possible that the
APIs might change.

Signed-off-by: Ilias Stamatis <ilstam@amazon.com>

Author: ilstam

src/vmm/src/lib.rs

@@ -143,7 +143,7 @@ use crate::devices::virtio::net::Net;
 use crate::devices::virtio::pmem::device::Pmem;
 use crate::devices::virtio::rng::Entropy;
 use crate::devices::virtio::vsock::{Vsock, VsockUnixBackend};
-use crate::logger::{METRICS, MetricsError};
+use crate::logger::{METRICS, MetricsError, log_dev_preview_warning};
 use crate::mmds::data_store::Mmds;
 use crate::persist::{MicrovmState, MicrovmStateError, VmInfo};
 use crate::rate_limiter::BucketUpdate;
@@ -706,6 +706,7 @@ impl Vmm {
         config: HotplugDeviceConfig,
         event_manager: &mut EventManager,
     ) -> Result<(), VmmActionError> {
+        log_dev_preview_warning("PCI device hotplug", None);
         let kvm_vm = self
             .vm
             .as_kvm()
@@ -722,6 +723,7 @@ impl Vmm {
         device_id: VirtioDeviceId,
         event_manager: &mut EventManager,
     ) -> Result<(), VmmActionError> {
+        log_dev_preview_warning("PCI device hot-unplug", None);
         let kvm_vm = self
             .vm
             .as_kvm()