hw/core/machine-smp.c

   1 /*
   2  * QEMU Machine core (related to -smp parsing)
   3  *
   4  * Copyright (c) 2021 Huawei Technologies Co., Ltd
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License,
   9  * or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "qemu/osdep.h"
  21 #include "hw/boards.h"
  22 #include "qapi/error.h"
  23
  24 /*
  25  * Report information of a machine's supported CPU topology hierarchy.
  26  * Topology members will be ordered from the largest to the smallest
  27  * in the string.
  28  */
  29 static char *cpu_hierarchy_to_string(MachineState *ms)
  30 {
  31     MachineClass *mc = MACHINE_GET_CLASS(ms);
  32     GString *s = g_string_new(NULL);
  33
  34     g_string_append_printf(s, "sockets (%u)", ms->smp.sockets);
  35
  36     if (mc->smp_props.dies_supported) {
  37         g_string_append_printf(s, " * dies (%u)", ms->smp.dies);
  38     }
  39
  40     if (mc->smp_props.clusters_supported) {
  41         g_string_append_printf(s, " * clusters (%u)", ms->smp.clusters);
  42     }
  43
  44     g_string_append_printf(s, " * cores (%u)", ms->smp.cores);
  45     g_string_append_printf(s, " * threads (%u)", ms->smp.threads);
  46
  47     return g_string_free(s, false);
  48 }
  49
  50 /*
  51  * machine_parse_smp_config: Generic function used to parse the given
  52  *                           SMP configuration
  53  *
  54  * Any missing parameter in "cpus/maxcpus/sockets/cores/threads" will be
  55  * automatically computed based on the provided ones.
  56  *
  57  * In the calculation of omitted sockets/cores/threads: we prefer sockets
  58  * over cores over threads before 6.2, while preferring cores over sockets
  59  * over threads since 6.2.
  60  *
  61  * In the calculation of cpus/maxcpus: When both maxcpus and cpus are omitted,
  62  * maxcpus will be computed from the given parameters and cpus will be set
  63  * equal to maxcpus. When only one of maxcpus and cpus is given then the
  64  * omitted one will be set to its given counterpart's value. Both maxcpus and
  65  * cpus may be specified, but maxcpus must be equal to or greater than cpus.
  66  *
  67  * For compatibility, apart from the parameters that will be computed, newly
  68  * introduced topology members which are likely to be target specific should
  69  * be directly set as 1 if they are omitted (e.g. dies for PC since 4.1).
  70  */
  71 void machine_parse_smp_config(MachineState *ms,
  72                               const SMPConfiguration *config, Error **errp)
  73 {
  74     MachineClass *mc = MACHINE_GET_CLASS(ms);
  75     unsigned cpus    = config->has_cpus ? config->cpus : 0;
  76     unsigned sockets = config->has_sockets ? config->sockets : 0;
  77     unsigned dies    = config->has_dies ? config->dies : 0;
  78     unsigned clusters = config->has_clusters ? config->clusters : 0;
  79     unsigned cores   = config->has_cores ? config->cores : 0;
  80     unsigned threads = config->has_threads ? config->threads : 0;
  81     unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
  82
  83     /*
  84      * Specified CPU topology parameters must be greater than zero,
  85      * explicit configuration like "cpus=0" is not allowed.
  86      */
  87     if ((config->has_cpus && config->cpus == 0) ||
  88         (config->has_sockets && config->sockets == 0) ||
  89         (config->has_dies && config->dies == 0) ||
  90         (config->has_clusters && config->clusters == 0) ||
  91         (config->has_cores && config->cores == 0) ||
  92         (config->has_threads && config->threads == 0) ||
  93         (config->has_maxcpus && config->maxcpus == 0)) {
  94         warn_report("Deprecated CPU topology (considered invalid): "
  95                     "CPU topology parameters must be greater than zero");
  96     }
  97
  98     /*
  99      * If not supported by the machine, a topology parameter must be
 100      * omitted or specified equal to 1.
 101      */
 102     if (!mc->smp_props.dies_supported && dies > 1) {
 103         error_setg(errp, "dies not supported by this machine's CPU topology");
 104         return;
 105     }
 106     if (!mc->smp_props.clusters_supported && clusters > 1) {
 107         error_setg(errp, "clusters not supported by this machine's CPU topology");
 108         return;
 109     }
 110
 111     dies = dies > 0 ? dies : 1;
 112     clusters = clusters > 0 ? clusters : 1;
 113
 114     /* compute missing values based on the provided ones */
 115     if (cpus == 0 && maxcpus == 0) {
 116         sockets = sockets > 0 ? sockets : 1;
 117         cores = cores > 0 ? cores : 1;
 118         threads = threads > 0 ? threads : 1;
 119     } else {
 120         maxcpus = maxcpus > 0 ? maxcpus : cpus;
 121
 122         if (mc->smp_props.prefer_sockets) {
 123             /* prefer sockets over cores before 6.2 */
 124             if (sockets == 0) {
 125                 cores = cores > 0 ? cores : 1;
 126                 threads = threads > 0 ? threads : 1;
 127                 sockets = maxcpus / (dies * clusters * cores * threads);
 128             } else if (cores == 0) {
 129                 threads = threads > 0 ? threads : 1;
 130                 cores = maxcpus / (sockets * dies * clusters * threads);
 131             }
 132         } else {
 133             /* prefer cores over sockets since 6.2 */
 134             if (cores == 0) {
 135                 sockets = sockets > 0 ? sockets : 1;
 136                 threads = threads > 0 ? threads : 1;
 137                 cores = maxcpus / (sockets * dies * clusters * threads);
 138             } else if (sockets == 0) {
 139                 threads = threads > 0 ? threads : 1;
 140                 sockets = maxcpus / (dies * clusters * cores * threads);
 141             }
 142         }
 143
 144         /* try to calculate omitted threads at last */
 145         if (threads == 0) {
 146             threads = maxcpus / (sockets * dies * clusters * cores);
 147         }
 148     }
 149
 150     maxcpus = maxcpus > 0 ? maxcpus : sockets * dies * clusters * cores * threads;
 151     cpus = cpus > 0 ? cpus : maxcpus;
 152
 153     ms->smp.cpus = cpus;
 154     ms->smp.sockets = sockets;
 155     ms->smp.dies = dies;
 156     ms->smp.clusters = clusters;
 157     ms->smp.cores = cores;
 158     ms->smp.threads = threads;
 159     ms->smp.max_cpus = maxcpus;
 160
 161     /* sanity-check of the computed topology */
 162     if (sockets * dies * clusters * cores * threads != maxcpus) {
 163         g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
 164         error_setg(errp, "Invalid CPU topology: "
 165                    "product of the hierarchy must match maxcpus: "
 166                    "%s != maxcpus (%u)",
 167                    topo_msg, maxcpus);
 168         return;
 169     }
 170
 171     if (maxcpus < cpus) {
 172         g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
 173         error_setg(errp, "Invalid CPU topology: "
 174                    "maxcpus must be equal to or greater than smp: "
 175                    "%s == maxcpus (%u) < smp_cpus (%u)",
 176                    topo_msg, maxcpus, cpus);
 177         return;
 178     }
 179
 180     if (ms->smp.cpus < mc->min_cpus) {
 181         error_setg(errp, "Invalid SMP CPUs %d. The min CPUs "
 182                    "supported by machine '%s' is %d",
 183                    ms->smp.cpus,
 184                    mc->name, mc->min_cpus);
 185         return;
 186     }
 187
 188     if (ms->smp.max_cpus > mc->max_cpus) {
 189         error_setg(errp, "Invalid SMP CPUs %d. The max CPUs "
 190                    "supported by machine '%s' is %d",
 191                    ms->smp.max_cpus,
 192                    mc->name, mc->max_cpus);
 193         return;
 194     }
 195 }