cpu: Use DeviceClass reset instead of a special CPUClass reset

The CPUClass has a 'reset' method.  This is a legacy from when
TYPE_CPU used not to inherit from TYPE_DEVICE.  We don't need it any
more, as we can simply use the TYPE_DEVICE reset.  The 'cpu_reset()'
function is kept as the API which most places use to reset a CPU; it
is now a wrapper which calls device_cold_reset() and then the
tracepoint function.

This change should not cause CPU objects to be reset more often
than they are at the moment, because:
 * nobody is directly calling device_cold_reset() or
   qdev_reset_all() on CPU objects
 * no CPU object is on a qbus, so they will not be reset either
   by somebody calling qbus_reset_all()/bus_cold_reset(), or
   by the main "reset sysbus and everything in the qbus tree"
   reset that most devices are reset by

Note that this does not change the need for each machine or whatever
to use qemu_register_reset() to arrange to call cpu_reset() -- that
is necessary because CPU objects are not on any qbus, so they don't
get reset when the qbus tree rooted at the sysbus bus is reset, and
this isn't being changed here.

All the changes to the files under target/ were made using the
included Coccinelle script, except:

(1) the deletion of the now-inaccurate and not terribly useful
"CPUClass::reset" comments was done with a perl one-liner afterwards:
  perl -n -i -e '/ CPUClass::reset/ or print' target/*/*.c

(2) this bit of the s390 change was done by hand, because the
Coccinelle script is not sophisticated enough to handle the
parent_reset call being inside another function:

| @@ -96,8 +96,9 @@ static void s390_cpu_reset(CPUState *s, cpu_reset_type type)
|     S390CPU *cpu = S390_CPU(s);
|     S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
|     CPUS390XState *env = &cpu->env;
|+    DeviceState *dev = DEVICE(s);
|
|-    scc->parent_reset(s);
|+    scc->parent_reset(dev);
|     cpu->env.sigp_order = 0;
|     s390_cpu_set_state(S390_CPU_STATE_STOPPED, cpu);

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200303100511.5498-1-peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

1 files changed, 4 insertions, 15 deletions

diff --git a/hw/core/cpu.c b/hw/core/cpu.c
index fe65ca62ac..b889878f3c 100644
--- a/hw/core/cpu.c
+++ b/hw/core/cpu.c
@@ -239,27 +239,16 @@ void cpu_dump_statistics(CPUState *cpu, int flags)
     }
 }
 
-void cpu_class_set_parent_reset(CPUClass *cc,
-                                void (*child_reset)(CPUState *cpu),
-                                void (**parent_reset)(CPUState *cpu))
-{
-    *parent_reset = cc->reset;
-    cc->reset = child_reset;
-}
-
 void cpu_reset(CPUState *cpu)
 {
-    CPUClass *klass = CPU_GET_CLASS(cpu);
-
-    if (klass->reset != NULL) {
-        (*klass->reset)(cpu);
-    }
+    device_cold_reset(DEVICE(cpu));
 
     trace_guest_cpu_reset(cpu);
 }
 
-static void cpu_common_reset(CPUState *cpu)
+static void cpu_common_reset(DeviceState *dev)
 {
+    CPUState *cpu = CPU(dev);
     CPUClass *cc = CPU_GET_CLASS(cpu);
 
     if (qemu_loglevel_mask(CPU_LOG_RESET)) {
@@ -419,7 +408,6 @@ static void cpu_class_init(ObjectClass *klass, void *data)
     CPUClass *k = CPU_CLASS(klass);
 
     k->parse_features = cpu_common_parse_features;
-    k->reset = cpu_common_reset;
     k->get_arch_id = cpu_common_get_arch_id;
     k->has_work = cpu_common_has_work;
     k->get_paging_enabled = cpu_common_get_paging_enabled;
@@ -440,6 +428,7 @@ static void cpu_class_init(ObjectClass *klass, void *data)
     set_bit(DEVICE_CATEGORY_CPU, dc->categories);
     dc->realize = cpu_common_realizefn;
     dc->unrealize = cpu_common_unrealizefn;
+    dc->reset = cpu_common_reset;
     device_class_set_props(dc, cpu_common_props);
     /*
      * Reason: CPUs still need special care by board code: wiring up