kvm: synchronize state from cpu context

It is not safe to retrieve the KVM internal state of a given cpu
while its potentially modifying it.

Queue the request to run on cpu context, similarly to qemu-kvm.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

kvm-all.c

@@ -796,14 +796,22 @@ void kvm_flush_coalesced_mmio_buffer(void)
 #endif
 }
 
-void kvm_cpu_synchronize_state(CPUState *env)
+static void do_kvm_cpu_synchronize_state(void *_env)
 {
+    CPUState *env = _env;
+
     if (!env->kvm_vcpu_dirty) {
         kvm_arch_get_registers(env);
         env->kvm_vcpu_dirty = 1;
     }
 }
 
+void kvm_cpu_synchronize_state(CPUState *env)
+{
+    if (!env->kvm_vcpu_dirty)
+        run_on_cpu(env, do_kvm_cpu_synchronize_state, env);
+}
+
 void kvm_cpu_synchronize_post_reset(CPUState *env)
 {
     kvm_arch_put_registers(env, KVM_PUT_RESET_STATE);