[Qemu-ppc] [PATCH] spapr: fix core unplug crash

[Greg Kurz]

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 is caused because spapr_core_unplug() assumes cpu_dt_id == core_id.
Even if it happens to be the case when the host and guest have the same
number of threads per core, it is conceptually wrong and we may pass a
bogus id to spapr_dr_connector_by_id() and spapr_core_release() crashes.

Let's use cc->core_id, which is the id that was used to create th DR
connector.

Signed-off-by: Greg Kurz <address@hidden>
---
 hw/ppc/spapr_cpu_core.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 70b6b0b5ee17..106eaf45b399 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -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;