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 #include "qemu/error-report.h"
  24
  25
  26 /*
  27  * Report information of a machine's supported CPU topology hierarchy.
  28  * Topology members will be ordered from the largest to the smallest
  29  * in the string.
  30  */
  31 static char *cpu_hierarchy_to_string(MachineState *ms)
  32 {
  33     MachineClass *mc = MACHINE_GET_CLASS(ms);
  34     GString *s = g_string_new(NULL);
  35
  36     g_string_append_printf(s, "sockets (%u)", ms->smp.sockets);
  37
  38     if (mc->smp_props.dies_supported) {
  39         g_string_append_printf(s, " * dies (%u)", ms->smp.dies);
  40     }
  41
  42     if (mc->smp_props.clusters_supported) {
  43         g_string_append_printf(s, " * clusters (%u)", ms->smp.clusters);
  44     }
  45
  46     g_string_append_printf(s, " * cores (%u)", ms->smp.cores);
  47     g_string_append_printf(s, " * threads (%u)", ms->smp.threads);
  48
  49     return g_string_free(s, false);
  50 }
  51
  52 /*
  53  * machine_parse_smp_config: Generic function used to parse the given
  54  *                           SMP configuration
  55  *
  56  * Any missing parameter in "cpus/maxcpus/sockets/cores/threads" will be
  57  * automatically computed based on the provided ones.
  58  *
  59  * In the calculation of omitted sockets/cores/threads: we prefer sockets
  60  * over cores over threads before 6.2, while preferring cores over sockets
  61  * over threads since 6.2.
  62  *
  63  * In the calculation of cpus/maxcpus: When both maxcpus and cpus are omitted,
  64  * maxcpus will be computed from the given parameters and cpus will be set
  65  * equal to maxcpus. When only one of maxcpus and cpus is given then the
  66  * omitted one will be set to its given counterpart's value. Both maxcpus and
  67  * cpus may be specified, but maxcpus must be equal to or greater than cpus.
  68  *
  69  * For compatibility, apart from the parameters that will be computed, newly
  70  * introduced topology members which are likely to be target specific should
  71  * be directly set as 1 if they are omitted (e.g. dies for PC since 4.1).
  72  */
  73 void machine_parse_smp_config(MachineState *ms,
  74                               const SMPConfiguration *config, Error **errp)
  75 {
  76     MachineClass *mc = MACHINE_GET_CLASS(ms);
  77     unsigned cpus    = config->has_cpus ? config->cpus : 0;
  78     unsigned sockets = config->has_sockets ? config->sockets : 0;
  79     unsigned dies    = config->has_dies ? config->dies : 0;
  80     unsigned clusters = config->has_clusters ? config->clusters : 0;
  81     unsigned cores   = config->has_cores ? config->cores : 0;
  82     unsigned threads = config->has_threads ? config->threads : 0;
  83     unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
  84
  85     /*
  86      * Specified CPU topology parameters must be greater than zero,
  87      * explicit configuration like "cpus=0" is not allowed.
  88      */
  89     if ((config->has_cpus && config->cpus == 0) ||
  90         (config->has_sockets && config->sockets == 0) ||
  91         (config->has_dies && config->dies == 0) ||
  92         (config->has_clusters && config->clusters == 0) ||
  93         (config->has_cores && config->cores == 0) ||
  94         (config->has_threads && config->threads == 0) ||
  95         (config->has_maxcpus && config->maxcpus == 0)) {
  96         warn_report("Deprecated CPU topology (considered invalid): "
  97                     "CPU topology parameters must be greater than zero");
  98     }
  99
 100     /*
 101      * If not supported by the machine, a topology parameter must be
 102      * omitted or specified equal to 1.
 103      */
 104     if (!mc->smp_props.dies_supported && dies > 1) {
 105         error_setg(errp, "dies not supported by this machine's CPU topology");
 106         return;
 107     }
 108     if (!mc->smp_props.clusters_supported && clusters > 1) {
 109         error_setg(errp, "clusters not supported by this machine's CPU topology");
 110         return;
 111     }
 112
 113     dies = dies > 0 ? dies : 1;
 114     clusters = clusters > 0 ? clusters : 1;
 115
 116     /* compute missing values based on the provided ones */
 117     if (cpus == 0 && maxcpus == 0) {
 118         sockets = sockets > 0 ? sockets : 1;
 119         cores = cores > 0 ? cores : 1;
 120         threads = threads > 0 ? threads : 1;
 121     } else {
 122         maxcpus = maxcpus > 0 ? maxcpus : cpus;
 123
 124         if (mc->smp_props.prefer_sockets) {
 125             /* prefer sockets over cores before 6.2 */
 126             if (sockets == 0) {
 127                 cores = cores > 0 ? cores : 1;
 128                 threads = threads > 0 ? threads : 1;
 129                 sockets = maxcpus / (dies * clusters * cores * threads);
 130             } else if (cores == 0) {
 131                 threads = threads > 0 ? threads : 1;
 132                 cores = maxcpus / (sockets * dies * clusters * threads);
 133             }
 134         } else {
 135             /* prefer cores over sockets since 6.2 */
 136             if (cores == 0) {
 137                 sockets = sockets > 0 ? sockets : 1;
 138                 threads = threads > 0 ? threads : 1;
 139                 cores = maxcpus / (sockets * dies * clusters * threads);
 140             } else if (sockets == 0) {
 141                 threads = threads > 0 ? threads : 1;
 142                 sockets = maxcpus / (dies * clusters * cores * threads);
 143             }
 144         }
 145
 146         /* try to calculate omitted threads at last */
 147         if (threads == 0) {
 148             threads = maxcpus / (sockets * dies * clusters * cores);
 149         }
 150     }
 151
 152     maxcpus = maxcpus > 0 ? maxcpus : sockets * dies * clusters * cores * threads;
 153     cpus = cpus > 0 ? cpus : maxcpus;
 154
 155     ms->smp.cpus = cpus;
 156     ms->smp.sockets = sockets;
 157     ms->smp.dies = dies;
 158     ms->smp.clusters = clusters;
 159     ms->smp.cores = cores;
 160     ms->smp.threads = threads;
 161     ms->smp.max_cpus = maxcpus;
 162
 163     mc->smp_props.has_clusters = config->has_clusters;
 164
 165     /* sanity-check of the computed topology */
 166     if (sockets * dies * clusters * cores * threads != maxcpus) {
 167         g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
 168         error_setg(errp, "Invalid CPU topology: "
 169                    "product of the hierarchy must match maxcpus: "
 170                    "%s != maxcpus (%u)",
 171                    topo_msg, maxcpus);
 172         return;
 173     }
 174
 175     if (maxcpus < cpus) {
 176         g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
 177         error_setg(errp, "Invalid CPU topology: "
 178                    "maxcpus must be equal to or greater than smp: "
 179                    "%s == maxcpus (%u) < smp_cpus (%u)",
 180                    topo_msg, maxcpus, cpus);
 181         return;
 182     }
 183
 184     if (ms->smp.cpus < mc->min_cpus) {
 185         error_setg(errp, "Invalid SMP CPUs %d. The min CPUs "
 186                    "supported by machine '%s' is %d",
 187                    ms->smp.cpus,
 188                    mc->name, mc->min_cpus);
 189         return;
 190     }
 191
 192     if (ms->smp.max_cpus > mc->max_cpus) {
 193         error_setg(errp, "Invalid SMP CPUs %d. The max CPUs "
 194                    "supported by machine '%s' is %d",
 195                    ms->smp.max_cpus,
 196                    mc->name, mc->max_cpus);
 197         return;
 198     }
 199 }