qemu

machine-smp.c (7464B)

---

 /*
  * QEMU Machine core (related to -smp parsing)
  *
  * Copyright (c) 2021 Huawei Technologies Co., Ltd
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License,
  * or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 
 #include "qemu/osdep.h"
 #include "hw/boards.h"
 #include "qapi/error.h"
 
 /*
  * Report information of a machine's supported CPU topology hierarchy.
  * Topology members will be ordered from the largest to the smallest
  * in the string.
  */
 static char *cpu_hierarchy_to_string(MachineState *ms)
 {
     MachineClass *mc = MACHINE_GET_CLASS(ms);
     GString *s = g_string_new(NULL);
 
     g_string_append_printf(s, "sockets (%u)", ms->smp.sockets);
 
     if (mc->smp_props.dies_supported) {
         g_string_append_printf(s, " * dies (%u)", ms->smp.dies);
     }
 
     if (mc->smp_props.clusters_supported) {
         g_string_append_printf(s, " * clusters (%u)", ms->smp.clusters);
     }
 
     g_string_append_printf(s, " * cores (%u)", ms->smp.cores);
     g_string_append_printf(s, " * threads (%u)", ms->smp.threads);
 
     return g_string_free(s, false);
 }
 
 /*
  * machine_parse_smp_config: Generic function used to parse the given
  *                           SMP configuration
  *
  * Any missing parameter in "cpus/maxcpus/sockets/cores/threads" will be
  * automatically computed based on the provided ones.
  *
  * In the calculation of omitted sockets/cores/threads: we prefer sockets
  * over cores over threads before 6.2, while preferring cores over sockets
  * over threads since 6.2.
  *
  * In the calculation of cpus/maxcpus: When both maxcpus and cpus are omitted,
  * maxcpus will be computed from the given parameters and cpus will be set
  * equal to maxcpus. When only one of maxcpus and cpus is given then the
  * omitted one will be set to its given counterpart's value. Both maxcpus and
  * cpus may be specified, but maxcpus must be equal to or greater than cpus.
  *
  * For compatibility, apart from the parameters that will be computed, newly
  * introduced topology members which are likely to be target specific should
  * be directly set as 1 if they are omitted (e.g. dies for PC since 4.1).
  */
 void machine_parse_smp_config(MachineState *ms,
                               const SMPConfiguration *config, Error **errp)
 {
     MachineClass *mc = MACHINE_GET_CLASS(ms);
     unsigned cpus    = config->has_cpus ? config->cpus : 0;
     unsigned sockets = config->has_sockets ? config->sockets : 0;
     unsigned dies    = config->has_dies ? config->dies : 0;
     unsigned clusters = config->has_clusters ? config->clusters : 0;
     unsigned cores   = config->has_cores ? config->cores : 0;
     unsigned threads = config->has_threads ? config->threads : 0;
     unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
 
     /*
      * Specified CPU topology parameters must be greater than zero,
      * explicit configuration like "cpus=0" is not allowed.
      */
     if ((config->has_cpus && config->cpus == 0) ||
         (config->has_sockets && config->sockets == 0) ||
         (config->has_dies && config->dies == 0) ||
         (config->has_clusters && config->clusters == 0) ||
         (config->has_cores && config->cores == 0) ||
         (config->has_threads && config->threads == 0) ||
         (config->has_maxcpus && config->maxcpus == 0)) {
         warn_report("Deprecated CPU topology (considered invalid): "
                     "CPU topology parameters must be greater than zero");
     }
 
     /*
      * If not supported by the machine, a topology parameter must be
      * omitted or specified equal to 1.
      */
     if (!mc->smp_props.dies_supported && dies > 1) {
         error_setg(errp, "dies not supported by this machine's CPU topology");
         return;
     }
     if (!mc->smp_props.clusters_supported && clusters > 1) {
         error_setg(errp, "clusters not supported by this machine's CPU topology");
         return;
     }
 
     dies = dies > 0 ? dies : 1;
     clusters = clusters > 0 ? clusters : 1;
 
     /* compute missing values based on the provided ones */
     if (cpus == 0 && maxcpus == 0) {
         sockets = sockets > 0 ? sockets : 1;
         cores = cores > 0 ? cores : 1;
         threads = threads > 0 ? threads : 1;
     } else {
         maxcpus = maxcpus > 0 ? maxcpus : cpus;
 
         if (mc->smp_props.prefer_sockets) {
             /* prefer sockets over cores before 6.2 */
             if (sockets == 0) {
                 cores = cores > 0 ? cores : 1;
                 threads = threads > 0 ? threads : 1;
                 sockets = maxcpus / (dies * clusters * cores * threads);
             } else if (cores == 0) {
                 threads = threads > 0 ? threads : 1;
                 cores = maxcpus / (sockets * dies * clusters * threads);
             }
         } else {
             /* prefer cores over sockets since 6.2 */
             if (cores == 0) {
                 sockets = sockets > 0 ? sockets : 1;
                 threads = threads > 0 ? threads : 1;
                 cores = maxcpus / (sockets * dies * clusters * threads);
             } else if (sockets == 0) {
                 threads = threads > 0 ? threads : 1;
                 sockets = maxcpus / (dies * clusters * cores * threads);
             }
         }
 
         /* try to calculate omitted threads at last */
         if (threads == 0) {
             threads = maxcpus / (sockets * dies * clusters * cores);
         }
     }
 
     maxcpus = maxcpus > 0 ? maxcpus : sockets * dies * clusters * cores * threads;
     cpus = cpus > 0 ? cpus : maxcpus;
 
     ms->smp.cpus = cpus;
     ms->smp.sockets = sockets;
     ms->smp.dies = dies;
     ms->smp.clusters = clusters;
     ms->smp.cores = cores;
     ms->smp.threads = threads;
     ms->smp.max_cpus = maxcpus;
 
     /* sanity-check of the computed topology */
     if (sockets * dies * clusters * cores * threads != maxcpus) {
         g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
         error_setg(errp, "Invalid CPU topology: "
                    "product of the hierarchy must match maxcpus: "
                    "%s != maxcpus (%u)",
                    topo_msg, maxcpus);
         return;
     }
 
     if (maxcpus < cpus) {
         g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
         error_setg(errp, "Invalid CPU topology: "
                    "maxcpus must be equal to or greater than smp: "
                    "%s == maxcpus (%u) < smp_cpus (%u)",
                    topo_msg, maxcpus, cpus);
         return;
     }
 
     if (ms->smp.cpus < mc->min_cpus) {
         error_setg(errp, "Invalid SMP CPUs %d. The min CPUs "
                    "supported by machine '%s' is %d",
                    ms->smp.cpus,
                    mc->name, mc->min_cpus);
         return;
     }
 
     if (ms->smp.max_cpus > mc->max_cpus) {
         error_setg(errp, "Invalid SMP CPUs %d. The max CPUs "
                    "supported by machine '%s' is %d",
                    ms->smp.max_cpus,
                    mc->name, mc->max_cpus);
         return;
     }
 }