Re: [Qemu-devel] [Qemu-ppc] [PATCH] spapr: move registration of "host" CPU core type to machine code

[Greg Kurz <groug@kaod.org>]

On Fri, 29 Sep 2017 08:41:11 +0200
Igor Mammedov <imammedo@redhat.com> wrote:
[...]
> > > I don't see from this commit a reason why it can't be done in cpu-models.c
> > > dependencies here are
> > >   mfpvr() - which probably should work without KVM    
> > 
> > Correct.
> >   
> > >   ppc_cpu_class_by_pvr() - should work fine if 'host' type is being
> > >                            registered as the last among the other CPU types    
> > 
> > We have:
> > 
> > ppc_cpu_class_by_pvr()
> >  object_class_get_list()
> >   object_class_foreach()
> >    object_class_foreach_tramp()
> >     type_initialize()
> >      type_get_parent()
> > 
> > type_initialize() recursively initializes all parent types, and
> > type_get_parent() aborts if the parent type isn't registered yet,
> > which may happen as long as all type_init() functions haven't been
> > called => ppc_cpu_class_by_pvr() cannot be safely called from a
> > type_init() function.  
> I don't get what you are trying to say,
> could you be more specific about what parent type might be not
> registered?

With the patch below applied, TYPE_CPU isn't registered at the
time we call ppc_cpu_class_by_pvr().

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index cb5777afa0b4..4445a292d578 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -123,8 +123,6 @@ static bool kvmppc_is_pr(KVMState *ks)
     return kvm_vm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
 }
 
-static int kvm_ppc_register_host_cpu_type(void);
-
 int kvm_arch_init(MachineState *ms, KVMState *s)
 {
     cap_interrupt_unset = kvm_check_extension(s, KVM_CAP_PPC_UNSET_IRQ);
@@ -163,8 +161,6 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
                         "VM to stall at times!\n");
     }
 
-    kvm_ppc_register_host_cpu_type();
-
     return 0;

 }
 
@@ -2487,7 +2483,7 @@ PowerPCCPUClass *kvm_ppc_get_host_cpu_class(void)
     return pvr_pcc;
 }
 
-static int kvm_ppc_register_host_cpu_type(void)
+int kvm_ppc_register_host_cpu_type(void)
 {
     TypeInfo type_info = {
         .name = TYPE_HOST_POWERPC_CPU,
diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
index d6be38ecafbd..a46c5a36402a 100644
--- a/target/ppc/kvm_ppc.h
+++ b/target/ppc/kvm_ppc.h
@@ -71,6 +71,7 @@ bool kvmppc_pvr_workaround_required(PowerPCCPU *cpu);
 
 bool kvmppc_is_mem_backend_page_size_ok(const char *obj_path);
 
+int kvm_ppc_register_host_cpu_type(void);
 #else
 
 static inline uint32_t kvmppc_get_tbfreq(void)
diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
index c6399a3a0d0d..b6e02c583836 100644
--- a/target/ppc/translate_init.c
+++ b/target/ppc/translate_init.c
@@ -10766,6 +10766,9 @@ static void ppc_cpu_register_types(void)
 {
     type_register_static(&ppc_cpu_type_info);
     type_register_static(&ppc_vhyp_type_info);
+#ifdef CONFIG_KVM
+    kvm_ppc_register_host_cpu_type();
+#endif
 }
 
 type_init(ppc_cpu_register_types)