diff options
Diffstat (limited to 'hw/core/machine-smp.c')
| -rw-r--r-- | hw/core/machine-smp.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/hw/core/machine-smp.c b/hw/core/machine-smp.c new file mode 100644 index 0000000000..116a0cbbfa --- /dev/null +++ b/hw/core/machine-smp.c @@ -0,0 +1,181 @@ +/* + * 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); + } + + 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); +} + +/* + * smp_parse - 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 smp_parse(MachineState *ms, 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 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_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; + } + + dies = dies > 0 ? dies : 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 * cores * threads); + } else if (cores == 0) { + threads = threads > 0 ? threads : 1; + cores = maxcpus / (sockets * dies * 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 * threads); + } else if (sockets == 0) { + threads = threads > 0 ? threads : 1; + sockets = maxcpus / (dies * cores * threads); + } + } + + /* try to calculate omitted threads at last */ + if (threads == 0) { + threads = maxcpus / (sockets * dies * cores); + } + } + + maxcpus = maxcpus > 0 ? maxcpus : sockets * dies * cores * threads; + cpus = cpus > 0 ? cpus : maxcpus; + + ms->smp.cpus = cpus; + ms->smp.sockets = sockets; + ms->smp.dies = dies; + ms->smp.cores = cores; + ms->smp.threads = threads; + ms->smp.max_cpus = maxcpus; + + /* sanity-check of the computed topology */ + if (sockets * dies * 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; + } +} |