vmm: Implement Pausable trait for Vcpu

We want each Vcpu to store the vCPU state upon VM pausing. This is the
reason why we need to explicitly implement the Pausable trait for the
Vcpu structure.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/cpu.rs

@@ -398,7 +398,15 @@ impl Vcpu {
 }
 
 const VCPU_SNAPSHOT_ID: &str = "vcpu";
-impl Pausable for Vcpu {}
+impl Pausable for Vcpu {
+    fn pause(&mut self) -> std::result::Result<(), MigratableError> {
+        Ok(())
+    }
+
+    fn resume(&mut self) -> std::result::Result<(), MigratableError> {
+        Ok(())
+    }
+}
 impl Snapshottable for Vcpu {
     fn id(&self) -> String {
         VCPU_SNAPSHOT_ID.to_string()
@@ -1322,24 +1330,23 @@ impl Pausable for CpuManager {
             state.signal_thread();
         }
 
-        #[cfg(target_arch = "x86_64")]
         for vcpu in self.vcpus.iter() {
-            vcpu.lock()
-                .unwrap()
-                .fd
-                .notify_guest_clock_paused()
-                .map_err(|e| {
-                    MigratableError::Pause(anyhow!(
-                        "Could not notify guest it has been paused {:?}",
-                        e
-                    ))
-                })?;
+            let mut vcpu = vcpu.lock().unwrap();
+            vcpu.pause()?;
+            #[cfg(target_arch = "x86_64")]
+            vcpu.fd.notify_guest_clock_paused().map_err(|e| {
+                MigratableError::Pause(anyhow!("Could not notify guest it has been paused {:?}", e))
+            })?;
         }
 
         Ok(())
     }
 
     fn resume(&mut self) -> std::result::Result<(), MigratableError> {
+        for vcpu in self.vcpus.iter() {
+            vcpu.lock().unwrap().resume()?;
+        }
+
         // Toggle the vCPUs pause boolean
         self.vcpus_pause_signalled.store(false, Ordering::SeqCst);