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/*
* 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;
}
}
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