Igor Mammedov <imamm...@redhat.com> writes: > 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 > reproducable on destination side. > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > --- > 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 a last resort if no easy, risk-free and elegant solution > emerges before 2.7 dev cycle ends.
I think this (or a modified version) is appropriate comment material to accompany the changes. Ok if you are sure this code is short-lived, but if it stays longer, a comment is definitely helpful. Maybe a bit of reasoning added to the error message is fine too. > --- > hw/i386/pc.c | 34 ++++++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index 33c5f97..75a92d0 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1762,6 +1762,23 @@ 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); > > @@ -1860,6 +1877,23 @@ 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 > */