i386/kvm: Do not sync nested state during runtime

Writing the nested state e.g. after a vmport access can invalidate
important parts of the kernel-internal state, and it is not needed as
well. So leave this out from KVM_PUT_RUNTIME_STATE.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Message-Id: <bdd53f40-4e60-f3ae-7ec6-162198214953@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/kvm.c

@@ -3563,12 +3563,12 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
 
     assert(cpu_is_stopped(cpu) || qemu_cpu_is_self(cpu));
 
-    ret = kvm_put_nested_state(x86_cpu);
-    if (ret < 0) {
-        return ret;
-    }
-
     if (level >= KVM_PUT_RESET_STATE) {
+        ret = kvm_put_nested_state(x86_cpu);
+        if (ret < 0) {
+            return ret;
+        }
+
         ret = kvm_put_msr_feature_control(x86_cpu);
         if (ret < 0) {
             return ret;