[v2,2/5] spapr: Unrealize vCPUs with qdev_unrealize()

Commit Message

Greg Kurz Oct. 15, 2020, 9:18 p.m. UTC

Since we introduced CPU hot-unplug in sPAPR, we don't unrealize the
vCPU objects explicitly. Instead, we let QOM handle that for us under
object_property_del_all() when the CPU core object is finalized. The
only thing we do is calling cpu_remove_sync() to tear the vCPU thread
down.

This happens to work but it is ugly because:
- we call qdev_realize() but the corresponding qdev_unrealize() is
  buried deep in the QOM code
- we call cpu_remove_sync() to undo qemu_init_vcpu() called by
  ppc_cpu_realize() in target/ppc/translate_init.c.inc
- the CPU init and teardown paths aren't really symmetrical

The latter didn't bite us so far but a future patch that greatly
simplifies the CPU core realize path needs it to avoid a crash
in QOM.

For all these reasons, have ppc_cpu_unrealize() to undo the changes
of ppc_cpu_realize() by calling cpu_remove_sync() at the right place,
and have the sPAPR CPU core code to call qdev_unrealize().

This requires to add a missing stub because translate_init.c.inc is
also compiled for user mode.

Signed-off-by: Greg Kurz <[e-mail]>
---
 accel/tcg/user-exec-stub.c      |    4 ++++
 hw/ppc/spapr_cpu_core.c         |    4 ++--
 target/ppc/translate_init.c.inc |    2 ++
 3 files changed, 8 insertions(+), 2 deletions(-)

Patch

diff --git a/accel/tcg/user-exec-stub.c b/accel/tcg/user-exec-stub.c
index f6d8c8fb6f2d..b876f5c1e45d 100644
--- a/accel/tcg/user-exec-stub.c
+++ b/accel/tcg/user-exec-stub.c
@@ -9,6 +9,10 @@  void cpu_resume(CPUState *cpu)
 {
 }
 
+void cpu_remove_sync(CPUState *cpu)
+{
+}
+
 void qemu_init_vcpu(CPUState *cpu)
 {
 }
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index c55211214524..e4aeb93c0299 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -187,7 +187,7 @@  static void spapr_unrealize_vcpu(PowerPCCPU *cpu, SpaprCpuCore *sc)
         vmstate_unregister(NULL, &vmstate_spapr_cpu_state, cpu->machine_data);
     }
     spapr_irq_cpu_intc_destroy(SPAPR_MACHINE(qdev_get_machine()), cpu);
-    cpu_remove_sync(CPU(cpu));
+    qdev_unrealize(DEVICE(cpu));
 }
 
 /*
@@ -255,7 +255,7 @@  static bool spapr_realize_vcpu(PowerPCCPU *cpu, SpaprMachineState *spapr,
     kvmppc_set_papr(cpu);
 
     if (spapr_irq_cpu_intc_create(spapr, cpu, errp) < 0) {
-        cpu_remove_sync(CPU(cpu));
+        qdev_unrealize(DEVICE(cpu));
         return false;
     }
 
diff --git a/target/ppc/translate_init.c.inc b/target/ppc/translate_init.c.inc
index bb66526280ef..d2a8204d6011 100644
--- a/target/ppc/translate_init.c.inc
+++ b/target/ppc/translate_init.c.inc
@@ -10328,6 +10328,8 @@  static void ppc_cpu_unrealize(DeviceState *dev)
 
     pcc->parent_unrealize(dev);
 
+    cpu_remove_sync(CPU(cpu));
+
     for (i = 0; i < PPC_CPU_OPCODES_LEN; i++) {
         if (cpu->opcodes[i] == &invalid_handler) {
             continue;