hw/core/machine-smp: Calculate total CPUs once in machine_parse_smp_config()

In machine_parse_smp_config(), the number of total CPUs is calculated
by:

    drawers * books * sockets * dies * clusters * cores * threads

To avoid missing the future new topology level, use a local variable to
cache the calculation result so that total CPUs are only calculated
once.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240308160148.3130837-4-zhao1.liu@linux.intel.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/core/machine-smp.c

@@ -91,6 +91,7 @@ void machine_parse_smp_config(MachineState *ms,
     unsigned cores   = config->has_cores ? config->cores : 0;
     unsigned threads = config->has_threads ? config->threads : 0;
     unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
+    unsigned total_cpus;
 
     /*
      * Specified CPU topology parameters must be greater than zero,
@@ -211,8 +212,8 @@ void machine_parse_smp_config(MachineState *ms,
         }
     }
 
-    maxcpus = maxcpus > 0 ? maxcpus : drawers * books * sockets * dies *
-                                      clusters * cores * threads;
+    total_cpus = drawers * books * sockets * dies * clusters * cores * threads;
+    maxcpus = maxcpus > 0 ? maxcpus : total_cpus;
     cpus = cpus > 0 ? cpus : maxcpus;
 
     ms->smp.cpus = cpus;
@@ -228,8 +229,7 @@ void machine_parse_smp_config(MachineState *ms,
     mc->smp_props.has_clusters = config->has_clusters;
 
     /* sanity-check of the computed topology */
-    if (drawers * books * sockets * dies * clusters * cores * threads !=
-        maxcpus) {
+    if (total_cpus != maxcpus) {
         g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
         error_setg(errp, "Invalid CPU topology: "
                    "product of the hierarchy must match maxcpus: "