As of pseries-2.7 and later, we require the total number of guest vcpus to
be a multiple of the threads-per-core. pseries-2.6 and earlier machine
types, however, are supposed to allow this for the sake of migration from
old qemu versions which allowed this.
Unfortunately,
8149e29 "pseries: Enforce homogeneous threads-per-core"
broke this by not considering the old machine type case. This fixes it by
only applying the check when the machine type supports hotpluggable cpus.
By not-entirely-coincidence, that corresponds to the same time when we
started enforcing total threads being a multiple of threads-per-core.
Fixes:
8149e2992f7811355cc34721b79d69d1a3a667dd
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Tested-by: Greg Kurz <groug@kaod.org>
goto out;
}
- if (cc->nr_threads != smp_threads) {
+ /*
+ * In general we should have homogeneous threads-per-core, but old
+ * (pre hotplug support) machine types allow the last core to have
+ * reduced threads as a compatibility hack for when we allowed
+ * total vcpus not a multiple of threads-per-core.
+ */
+ if (mc->has_hotpluggable_cpus && (cc->nr_threads != smp_threads)) {
error_setg(errp, "invalid nr-threads %d, must be %d",
cc->nr_threads, smp_threads);
return;