runtime-rs: ch: Change state when VM stopped

Make the CH (Cloud Hypervisor) `stop_vm()` method check the VM state before
attempting to stop the VM, and update the state once the VM has stopped.

This avoids the method failing if called multiple times which will
happen if the workload exits before the container manager requests that
the container stop.

This change ensures the CH driver finishes cleanly.

Fixes: #8629.

Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>

src/runtime-rs/crates/hypervisor/src/ch/inner_hypervisor.rs

@@ -631,7 +631,18 @@ impl CloudHypervisorInner {
     }
 
     pub(crate) fn stop_vm(&mut self) -> Result<()> {
-        block_on(self.cloud_hypervisor_shutdown())?;
+        // If the container workload exits, this method gets called. However,
+        // the container manager always makes a ShutdownContainer request,
+        // which results in this method being called potentially a second
+        // time. Without this check, we'll return an error representing EPIPE
+        // since the CH API socket is at that point invalid.
+        if self.state != VmmState::VmRunning {
+            return Ok(());
+        }
+
+        self.state = VmmState::NotReady;
+
+        block_on(self.cloud_hypervisor_shutdown()).map_err(|e| anyhow!(e))?;
 
         Ok(())
     }