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spapr: fix core unplug crash

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If the host has 8 threads/core and the guest is started with:

-smp cores=1,threads=4,maxcpus=12

It is possible to crash QEMU by doing:

(qemu) device_add host-spapr-cpu-core,core-id=16,id=foo
(qemu) device_del foo
Segmentation fault

This happens because spapr_core_unplug() assumes cpu_dt_id == core_id.
As long as cpu_dt_id is derived from the non-table cpu_index, this is
only true when you plug cores with contiguous ids.

It is safer to be consistent: the DR connector was created with an
index that is immediately written to cc->core_id, and spapr_core_plug()
also relies on cc->core_id.

Let's use it also in spapr_core_unplug().

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Greg Kurz 2016-07-08 15:12:07 +02:00 committed by David Gibson
parent 6b92bbfe81
commit 44d691f7d9
1 changed files with 2 additions and 4 deletions
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6
hw/ppc/spapr_cpu_core.c
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@ -126,11 +126,9 @@ static void spapr_core_release(DeviceState *dev, void *opaque)
void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
Error **errp)
{
sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
PowerPCCPU *cpu = POWERPC_CPU(core->threads);
int id = ppc_get_vcpu_dt_id(cpu);
CPUCore *cc = CPU_CORE(dev);
sPAPRDRConnector *drc =
spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core_id);
sPAPRDRConnectorClass *drck;
Error *local_err = NULL;