+#ifdef CONFIG_HOTPLUG_CPU
+ /* This is akin to using 'nr_cpus' on the Linux command line.
+ * Which is OK as when we use 'dom0_max_vcpus=X' we can only
+ * have up to X, while nr_cpu_ids is greater than X. This
+ * normally is not a problem, except when CPU hotplugging
+ * is involved and then there might be more than X CPUs
+ * in the guest - which will not work as there is no
+ * hypercall to expand the max number of VCPUs an already
+ * running guest has. So cap it up to X. */
+ if (subtract)
+ nr_cpu_ids = nr_cpu_ids - subtract;
+#endif
+