There is a race between when the vcpu thread issues a create ioctl and when
apic_reset() gets called resulting in getting a badfd error.

main thread                vcpu thread
diff --git a/qemu/qemu-kvm.c b/qemu/qemu-kvm.c
index 78127de..3513e8c 100644
--- a/qemu/qemu-kvm.c
+++ b/qemu/qemu-kvm.c
@@ -31,7 +31,9 @@ extern int smp_cpus;
 static int qemu_kvm_reset_requested;
 
 pthread_mutex_t qemu_mutex = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t vcpu_mutex = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t qemu_aio_cond = PTHREAD_COND_INITIALIZER;
+pthread_cond_t qemu_vcpuup_cond = PTHREAD_COND_INITIALIZER;
 __thread struct vcpu_info *vcpu;
 
 struct qemu_kvm_signal_table {
@@ -369,6 +371,11 @@ static void *ap_main_loop(void *_env)
     sigfillset(&signals);
     sigprocmask(SIG_BLOCK, &signals, NULL);
     kvm_create_vcpu(kvm_context, env->cpu_index);
+    /* block until cond_wait occurs */
+    pthread_mutex_lock(&vcpu_mutex);
+    /* now we can signal */
+    pthread_cond_signal(&qemu_vcpuup_cond);
+    pthread_mutex_unlock(&vcpu_mutex);
     kvm_qemu_init_env(env);
     kvm_main_loop_cpu(env);
     return NULL;
@@ -388,9 +395,10 @@ static void kvm_add_signal(struct qemu_kvm_signal_table 
*sigtab, int signum)
 
 void kvm_init_new_ap(int cpu, CPUState *env)
 {
+    pthread_mutex_lock(&vcpu_mutex);
     pthread_create(&vcpu_info[cpu].thread, NULL, ap_main_loop, env);
-    /* FIXME: wait for thread to spin up */
-    usleep(200);
+    pthread_cond_wait(&qemu_vcpuup_cond, &vcpu_mutex);
+    pthread_mutex_unlock(&vcpu_mutex);
 }
 
 static void qemu_kvm_init_signal_tables(void)

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