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