diff --git a/usr.sbin/bhyve/aarch64/vmexit.c b/usr.sbin/bhyve/aarch64/vmexit.c
--- a/usr.sbin/bhyve/aarch64/vmexit.c
+++ b/usr.sbin/bhyve/aarch64/vmexit.c
@@ -216,7 +216,7 @@
 			break;
 		}
 
-		if (CPU_ISSET(newcpu, &running_cpumask)) {
+		if (CPU_TEST_SET_ATOMIC(newcpu, &running_cpumask)) {
 			smccc_rv = PSCI_RETVAL_ALREADY_ON;
 			break;
 		}
@@ -235,7 +235,6 @@
 		assert(error == 0);
 
 		vm_resume_cpu(newvcpu);
-		CPU_SET_ATOMIC(newcpu, &running_cpumask);
 
 		smccc_rv = PSCI_RETVAL_SUCCESS;
 		break;