fix(vmm): call KVMCLOCK_CTRL when pausing

This is to avoid guest kernel panic on resume path
due to softlockup detection.

Signed-off-by: Nikita Kalyazin <[email protected]>
Signed-off-by: Babis Chalios <[email protected]>

Author: kalyazin

src/vmm/src/vstate/vcpu/mod.rs

@@ -336,8 +336,15 @@ impl Vcpu {
                     .send(VcpuResponse::Paused)
                     .expect("vcpu channel unexpectedly closed");
 
-                // TODO: we should call `KVM_KVMCLOCK_CTRL` here to make sure
-                // TODO continued: the guest soft lockup watchdog does not panic on Resume.
+                // Calling `KVM_KVMCLOCK_CTRL` to make sure the guest softlockup watchdog
+                // does not panic on resume, see https://docs.kernel.org/virt/kvm/api.html .
+                // We do not want to fail if the call is not successful, because depending
+                // that may be acceptable depending on the workload.
+                // TODO: add a metric
+                #[cfg(target_arch = "x86_64")]
+                if let Err(err) = self.kvm_vcpu.fd.kvmclock_ctrl() {
+                    warn!("KVM_KVMCLOCK_CTRL call failed {}", err);
+                }
 
                 // Move to 'paused' state.
                 state = StateMachine::next(Self::paused);