vmm: Activate virtio device from VMM thread

When a device is ready to be activated signal to the VMM thread via an
EventFd that there is a device to be activated. When the VMM receives a
notification on the EventFd that there is a device to be activated
notify the device manager to attempt to activate any devices that have
not been activated.

As a side effect the VMM thread will create the virtio device threads.

Fixes: #1863

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vmm/src/vm.rs

@@ -227,6 +227,9 @@ pub enum Error {
 
     /// Failed setting the VmmOps interface.
     SetVmmOpsInterface(hypervisor::HypervisorVmError),
+
+    /// Cannot activate virtio devices
+    ActivateVirtioDevices(device_manager::DeviceManagerError),
 }
 pub type Result<T> = result::Result<T, Error>;
 
@@ -488,6 +491,7 @@ impl Vm {
         seccomp_action: &SeccompAction,
         hypervisor: Arc<dyn hypervisor::Hypervisor>,
         #[cfg(feature = "kvm")] _saved_clock: Option<hypervisor::ClockData>,
+        activate_evt: EventFd,
     ) -> Result<Self> {
         config
             .lock()
@@ -509,6 +513,7 @@ impl Vm {
             seccomp_action.clone(),
             #[cfg(feature = "acpi")]
             numa_nodes.clone(),
+            &activate_evt,
         )
         .map_err(Error::DeviceManager)?;
 
@@ -646,6 +651,7 @@ impl Vm {
         reset_evt: EventFd,
         seccomp_action: &SeccompAction,
         hypervisor: Arc<dyn hypervisor::Hypervisor>,
+        activate_evt: EventFd,
     ) -> Result<Self> {
         #[cfg(all(feature = "kvm", target_arch = "x86_64"))]
         hypervisor.check_required_extensions().unwrap();
@@ -682,6 +688,7 @@ impl Vm {
             hypervisor,
             #[cfg(feature = "kvm")]
             None,
+            activate_evt,
         )?;
 
         // The device manager must create the devices from here as it is part
@@ -704,6 +711,7 @@ impl Vm {
         prefault: bool,
         seccomp_action: &SeccompAction,
         hypervisor: Arc<dyn hypervisor::Hypervisor>,
+        activate_evt: EventFd,
     ) -> Result<Self> {
         #[cfg(all(feature = "kvm", target_arch = "x86_64"))]
         hypervisor.check_required_extensions().unwrap();
@@ -746,6 +754,7 @@ impl Vm {
             hypervisor,
             #[cfg(feature = "kvm")]
             None,
+            activate_evt,
         )
     }
 
@@ -755,6 +764,7 @@ impl Vm {
         reset_evt: EventFd,
         seccomp_action: &SeccompAction,
         hypervisor: Arc<dyn hypervisor::Hypervisor>,
+        activate_evt: EventFd,
     ) -> Result<Self> {
         #[cfg(all(feature = "kvm", target_arch = "x86_64"))]
         hypervisor.check_required_extensions().unwrap();
@@ -781,6 +791,7 @@ impl Vm {
             hypervisor,
             #[cfg(feature = "kvm")]
             None,
+            activate_evt,
         )
     }
 
@@ -1739,6 +1750,14 @@ impl Vm {
     pub fn device_tree(&self) -> Arc<Mutex<DeviceTree>> {
         self.device_manager.lock().unwrap().device_tree()
     }
+
+    pub fn activate_virtio_devices(&self) -> Result<()> {
+        self.device_manager
+            .lock()
+            .unwrap()
+            .activate_virtio_devices()
+            .map_err(Error::ActivateVirtioDevices)
+    }
 }
 
 impl Pausable for Vm {