Re: [Qemu-devel] [RFC PATCH v0 1/5] cpu: Factor out cpu vmstate_[un]register into separate routines

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Tue, Jul 05, 2016 at 07:49:38AM +0200, Igor Mammedov wrote:
> On Tue, 5 Jul 2016 10:46:07 +0530
> Bharata B Rao <bharata@linux.vnet.ibm.com> wrote:
> 
> > On Tue, Jul 05, 2016 at 02:56:13PM +1000, David Gibson wrote:
> > > On Tue, Jul 05, 2016 at 10:12:48AM +0530, Bharata B Rao wrote:
> > > > Consolidates cpu vmstate_[un]register calls into separate
> > > > routines. No functionality change except that vmstate_unregister
> > > > calls are now done under !CONFIG_USER_ONLY to match with
> > > > vmstate_register calls.
> > > > 
> > > > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > > 
> > > Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> > > 
> > > > ---
> > > >  exec.c | 47 ++++++++++++++++++++++++++++-------------------
> > > >  1 file changed, 28 insertions(+), 19 deletions(-)
> > > > 
> > > > diff --git a/exec.c b/exec.c
> > > > index 0122ef7..8ce8e90 100644
> > > > --- a/exec.c
> > > > +++ b/exec.c
> > > > @@ -594,9 +594,7 @@ AddressSpace *cpu_get_address_space(CPUState
> > > > *cpu, int asidx) /* Return the AddressSpace corresponding to the
> > > > specified index */ return cpu->cpu_ases[asidx].as;
> > > >  }
> > > > -#endif
> > > >  
> > > > -#ifndef CONFIG_USER_ONLY
> > > >  static DECLARE_BITMAP(cpu_index_map, MAX_CPUMASK_BITS);
> > > >  
> > > >  static int cpu_get_free_index(Error **errp)
> > > > @@ -617,6 +615,31 @@ static void cpu_release_index(CPUState *cpu)
> > > >  {
> > > >      bitmap_clear(cpu_index_map, cpu->cpu_index, 1);
> > > >  }
> > > > +
> > > > +static void cpu_vmstate_register(CPUState *cpu)
> > > > +{
> > > > +    CPUClass *cc = CPU_GET_CLASS(cpu);
> > > > +
> > > > +    if (qdev_get_vmsd(DEVICE(cpu)) == NULL) {
> > > > +        vmstate_register(NULL, cpu->cpu_index,
> > > > &vmstate_cpu_common, cpu);
> > > > +    }
> > > > +    if (cc->vmsd != NULL) {
> > > > +        vmstate_register(NULL, cpu->cpu_index, cc->vmsd, cpu);
> > > > +    }
> > > > +}
> > > > +
> > > > +static void cpu_vmstate_unregister(CPUState *cpu)
> > > > +{
> > > > +    CPUClass *cc = CPU_GET_CLASS(cpu);
> > > > +
> > > > +    if (cc->vmsd != NULL) {
> > > > +        vmstate_unregister(NULL, cc->vmsd, cpu);
> > > > +    }
> > > > +    if (qdev_get_vmsd(DEVICE(cpu)) == NULL) {
> > > > +        vmstate_unregister(NULL, &vmstate_cpu_common, cpu);
> > > > +    }
> > > > +}
> > > > +
> > > 
> > > Given you're factoring this out, would it make sense to defined
> > > no-op versions for CONFIG_USER_ONLY, to reduce the amount of ifdefs
> > > at the call site?
> > 
> > I did that in a subsequent patch that moved the calls to these
> > routines into cpu_common_[un]realize()cpu_common_[un]realize(), but ended up in some
> > unrelated issue and hence didn't include that patch yet.
> I'd prefer to see it moved to cpu_common_[un]realize() directly
> without tis intermediate transition as compat logic could be
> implemented much cleaner if it's there.

If I implement cpu_common_unrealize() and the associated logic similar
to the existing cpu_common_realize(), it would involve changes to all
archs. I have done the change only to ppc in the below experimental patch.
Is this kind of change preferred or is it possible to do this in
non-invasive way ?

diff --git a/exec.c b/exec.c
index 2e8ad14..5274cc8 100644
--- a/exec.c
+++ b/exec.c
@@ -617,7 +617,7 @@ static void cpu_release_index(CPUState *cpu)
 }
 
 /* TODO: cpu_index is int while .get_arch_id()is int64_t */
-static void cpu_vmstate_register(CPUState *cpu)
+void cpu_vmstate_register(CPUState *cpu)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
     int instance_id = cpu->prefer_arch_id_over_cpu_index ?
@@ -631,7 +631,7 @@ static void cpu_vmstate_register(CPUState *cpu)
     }
 }
 
-static void cpu_vmstate_unregister(CPUState *cpu)
+void cpu_vmstate_unregister(CPUState *cpu)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
 
@@ -660,6 +660,14 @@ static void cpu_release_index(CPUState *cpu)
 {
     return;
 }
+
+void cpu_vmstate_register(CPUState *cpu)
+{
+}
+
+void cpu_vmstate_unregister(CPUState *cpu)
+{
+}
 #endif
 
 void cpu_exec_exit(CPUState *cpu)
@@ -680,8 +688,6 @@ void cpu_exec_exit(CPUState *cpu)
     cpu->cpu_index = -1;
 #if defined(CONFIG_USER_ONLY)
     cpu_list_unlock();
-#else
-    cpu_vmstate_unregister(cpu);
 #endif
 }
 
@@ -724,8 +730,6 @@ void cpu_exec_init(CPUState *cpu, Error **errp)
     QTAILQ_INSERT_TAIL(&cpus, cpu, node);
 #if defined(CONFIG_USER_ONLY)
     cpu_list_unlock();
-#else
-    cpu_vmstate_register(cpu);
 #endif
 }
 
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 1f1706e..08eab39 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -874,4 +874,6 @@ extern const struct VMStateDescription vmstate_cpu_common;
     .offset = 0,                                                            \
 }
 
+void cpu_vmstate_register(CPUState *cpu);
+void cpu_vmstate_unregister(CPUState *cpu);
 #endif
diff --git a/qom/cpu.c b/qom/cpu.c
index 751e992..65623e8 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -314,12 +314,20 @@ static void cpu_common_realizefn(DeviceState *dev, Error **errp)
 {
     CPUState *cpu = CPU(dev);
 
+    cpu_vmstate_register(cpu);
     if (dev->hotplugged) {
         cpu_synchronize_post_init(cpu);
         cpu_resume(cpu);
     }
 }
 
+static void cpu_common_unrealizefn(DeviceState *dev, Error **errp)
+{
+    CPUState *cpu = CPU(dev);
+
+    cpu_vmstate_unregister(cpu);
+}
+
 static void cpu_common_initfn(Object *obj)
 {
     CPUState *cpu = CPU(obj);
@@ -367,6 +375,7 @@ static void cpu_class_init(ObjectClass *klass, void *data)
     k->cpu_exec_exit = cpu_common_noop;
     k->cpu_exec_interrupt = cpu_common_exec_interrupt;
     dc->realize = cpu_common_realizefn;
+    dc->unrealize = cpu_common_unrealizefn;
     /*
      * Reason: CPUs still need special care by board code: wiring up
      * IRQs, adding reset handlers, halting non-first CPUs, ...
diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
index 2864105..9b8fe36 100644
--- a/target-ppc/cpu-qom.h
+++ b/target-ppc/cpu-qom.h
@@ -173,6 +173,7 @@ typedef struct PowerPCCPUClass {
     /*< public >*/
 
     DeviceRealize parent_realize;
+    DeviceUnrealize parent_unrealize;
     void (*parent_reset)(CPUState *cpu);
 
     uint32_t pvr;
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index 09602be..f4986e4 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -9743,10 +9743,12 @@ static void ppc_cpu_realizefn(DeviceState *dev, Error **errp)
 static void ppc_cpu_unrealizefn(DeviceState *dev, Error **errp)
 {
     PowerPCCPU *cpu = POWERPC_CPU(dev);
+    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
     CPUPPCState *env = &cpu->env;
     opc_handler_t **table;
     int i, j;
 
+    pcc->parent_unrealize(dev, errp);
     cpu_exec_exit(CPU(dev));
 
     for (i = 0; i < PPC_CPU_OPCODES_LEN; i++) {
@@ -10336,6 +10338,7 @@ static void ppc_cpu_class_init(ObjectClass *oc, void *data)
     DeviceClass *dc = DEVICE_CLASS(oc);
 
     pcc->parent_realize = dc->realize;
+    pcc->parent_unrealize = dc->unrealize;
     pcc->pvr_match = ppc_pvr_match_default;
     pcc->interrupts_big_endian = ppc_cpu_interrupts_big_endian_always;
     dc->realize = ppc_cpu_realizefn;