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pc: Enforce adding CPUs contiguously and removing them in opposite order

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It will still allow us to use cpu_index as migration instance_id
since when CPUs are added contiguously (from the first to the last)
and removed in opposite order, cpu_index stays stable and it's
reproducible on destination side.

While there is work in progress to support migration when there
are holes in cpu_index range resulting from out-of-order plug or
unplug, this patch is intended as an interim solution until
cpu_index usage is cleaned up.

As result of this patch it would be possible to plug/unplug CPUs,
but in limited order that doesn't break migration.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Igor Mammedov 2016-07-18 10:32:36 +02:00 committed by Eduardo Habkost
parent 73360e2785
commit 4da7faaeb0
1 changed files with 34 additions and 0 deletions
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34
hw/i386/pc.c
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@ -1815,6 +1815,23 @@ static void pc_cpu_unplug_request_cb(HotplugHandler *hotplug_dev,
goto out;
}
if (idx < pcms->possible_cpus->len - 1 &&
pcms->possible_cpus->cpus[idx + 1].cpu != NULL) {
X86CPU *cpu;
for (idx = pcms->possible_cpus->len - 1;
pcms->possible_cpus->cpus[idx].cpu == NULL; idx--) {
;;
}
cpu = X86_CPU(pcms->possible_cpus->cpus[idx].cpu);
error_setg(&local_err, "CPU [socket-id: %u, core-id: %u,"
" thread-id: %u] should be removed first",
cpu->socket_id, cpu->core_id, cpu->thread_id);
goto out;
}
hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
hhc->unplug_request(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &local_err);
@ -1912,6 +1929,23 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
return;
}
if (idx != 0 && pcms->possible_cpus->cpus[idx - 1].cpu == NULL) {
PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
for (idx = 1; pcms->possible_cpus->cpus[idx].cpu != NULL; idx++) {
;;
}
x86_topo_ids_from_apicid(pcms->possible_cpus->cpus[idx].arch_id,
smp_cores, smp_threads, &topo);
if (!pcmc->legacy_cpu_hotplug) {
error_setg(errp, "CPU [socket: %u, core: %u, thread: %u] should be"
" added first", topo.pkg_id, topo.core_id, topo.smt_id);
return;
}
}
/* if 'address' properties socket-id/core-id/thread-id are not set, set them
* so that query_hotpluggable_cpus would show correct values
*/