Re: [Qemu-devel] [PATCH 11/28] s390x: replace cpu_s390x_init() with cpu_generic_init()

[Igor Mammedov]

On Tue, 18 Jul 2017 14:30:09 +0200
Cornelia Huck <address@hidden> wrote:

> On Fri, 14 Jul 2017 15:52:02 +0200
> Igor Mammedov <address@hidden> wrote:
> 
> > cpu_s390x_init() is used only *-user targets indirectly
> > via cpu_init() macro and has a hack to assign ids to created
> > cpus (I'm not sure if 'id' really matters to *-user emulation).
> > 
> > So to on safe side, instead of having custom wrapper to do numbering
> > replace it with cpu_generic_init() and use S390CPUClass::next_cpu_id
> > which could serve the same purpose as static variable and move cpu->id
> > initialization to s390_cpu_initfn for CONFIG_USER_ONLY use-case.
> > 
> > PS:
> > ifdef is ugly but it allows us to hide s390x detail that isn't
> > set by *-user targets and reuse generic cpu creation utility
> > for btoh machine and user emulation.
> > 
> > Signed-off-by: Igor Mammedov <address@hidden>
> > ---
> > perhaps cpu->id isn't need by CONFIG_USER_ONLY but I'd leave to it
> > s390x maintainers to deal with it.
> > 
> > CC: Richard Henderson <address@hidden>
> > CC: Alexander Graf <address@hidden>
> > CC: Cornelia Huck <address@hidden>
> > CC: Thomas Huth <address@hidden>
> > ---
> >  target/s390x/cpu.h    |  3 +--
> >  target/s390x/cpu.c    |  7 +++++++
> >  target/s390x/helper.c | 14 --------------
> >  3 files changed, 8 insertions(+), 16 deletions(-)
> > 
> > diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> > index bdb9bdb..b6d25c6 100644
> > --- a/target/s390x/cpu.h
> > +++ b/target/s390x/cpu.h
> > @@ -477,7 +477,6 @@ static inline bool get_per_in_range(CPUS390XState *env, 
> > uint64_t addr)
> >  void trigger_pgm_exception(CPUS390XState *env, uint32_t code, uint32_t 
> > ilen);
> >  #endif
> >  
> > -S390CPU *cpu_s390x_init(const char *cpu_model);
> >  S390CPU *s390x_new_cpu(const char *cpu_model, int64_t id, Error **errp);
> >  S390CPU *cpu_s390x_create(const char *cpu_model, Error **errp);
> >  void s390x_translate_init(void);
> > @@ -641,7 +640,7 @@ static inline unsigned int s390_cpu_set_state(uint8_t 
> > cpu_state, S390CPU *cpu)
> >  
> >  extern void subsystem_reset(void);
> >  
> > -#define cpu_init(model) CPU(cpu_s390x_init(model))
> > +#define cpu_init(cpu_model) cpu_generic_init(TYPE_S390_CPU, cpu_model)
> >  #define cpu_signal_handler cpu_s390x_signal_handler
> >  
> >  void s390_cpu_list(FILE *f, fprintf_function cpu_fprintf);
> > diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
> > index accef03..e40a26f 100644
> > --- a/target/s390x/cpu.c
> > +++ b/target/s390x/cpu.c
> > @@ -303,6 +303,13 @@ static void s390_cpu_initfn(Object *obj)
> >          inited = true;
> >          s390x_translate_init();
> >      }
> > +
> > +#if defined(CONFIG_USER_ONLY)
> > +    {
> > +        S390CPUClass *scc = S390_CPU_GET_CLASS(obj);
> > +        cpu->id = scc->next_cpu_id;
> > +    }
> > +#endif  
> 
> What about the null machine, which calls cpu_init() as well? Am I
> missing something?
it creates only 1 cpu so for it following will be true:
 cpu->id == 0 and also scc->next_cpu_id == 0 at s390_cpu_initfn() time
then at realize() time scc->next_cpu_id++ happens and no more cpus could
be created in case of null machine.

Considering no -smp support for null-machine, we shouldn't care about
multiple instantiations with cpu_init() there. 
If we would ever start caring about -smp there, then we should
explicitly create cpus with properly set properties like other boards
do.


> 
> >  }
> >  
> >  static void s390_cpu_finalize(Object *obj)
> > diff --git a/target/s390x/helper.c b/target/s390x/helper.c
> > index aef09e1..632b030 100644
> > --- a/target/s390x/helper.c
> > +++ b/target/s390x/helper.c
> > @@ -129,20 +129,6 @@ out:
> >      return cpu;
> >  }
> >  
> > -S390CPU *cpu_s390x_init(const char *cpu_model)
> > -{
> > -    Error *err = NULL;
> > -    S390CPU *cpu;
> > -    /* Use to track CPU ID for linux-user only */
> > -    static int64_t next_cpu_id;
> > -
> > -    cpu = s390x_new_cpu(cpu_model, next_cpu_id++, &err);
> > -    if (err) {
> > -        error_report_err(err);
> > -    }
> > -    return cpu;
> > -}
> > -
> >  #if defined(CONFIG_USER_ONLY)
> >  
> >  void s390_cpu_do_interrupt(CPUState *cs)  
>