Re: [Qemu-devel] [PATCH v8 6/7] s390x/cpu: Add error handling to cpu creation

[David Hildenbrand <dahi@linux.vnet.ibm.com>]

> Check for and propogate errors during s390 cpu creation.
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
> ---
>  hw/s390x/s390-virtio.c |  2 +-
>  target-s390x/cpu-qom.h |  1 +
>  target-s390x/cpu.c     | 56 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  target-s390x/cpu.h     |  2 ++
>  target-s390x/helper.c  | 42 +++++++++++++++++++++++++++++++++++--
>  5 files changed, 99 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/s390x/s390-virtio.c b/hw/s390x/s390-virtio.c
> index f00d6b4..2ab7b94 100644
> --- a/hw/s390x/s390-virtio.c
> +++ b/hw/s390x/s390-virtio.c
> @@ -116,7 +116,7 @@ void s390_init_cpus(MachineState *machine)
>      }
> 
>      for (i = 0; i < smp_cpus; i++) {
> -        cpu_s390x_init(machine->cpu_model);
> +        s390_new_cpu(machine->cpu_model, i, &error_fatal);
>      }
>  }
> 
> diff --git a/target-s390x/cpu-qom.h b/target-s390x/cpu-qom.h
> index 56d82f2..1c90933 100644
> --- a/target-s390x/cpu-qom.h
> +++ b/target-s390x/cpu-qom.h
> @@ -68,6 +68,7 @@ typedef struct S390CPU {
>      /*< public >*/
> 
>      CPUS390XState env;
> +    int64_t id;
>      /* needed for live migration */
>      void *irqstate;
>      uint32_t irqstate_saved_size;
> diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
> index 76c8eaf..d1b7af9 100644
> --- a/target-s390x/cpu.c
> +++ b/target-s390x/cpu.c
> @@ -30,8 +30,10 @@
>  #include "qemu/error-report.h"
>  #include "hw/hw.h"
>  #include "trace.h"
> +#include "qapi/visitor.h"
>  #ifndef CONFIG_USER_ONLY
>  #include "sysemu/arch_init.h"
> +#include "sysemu/sysemu.h"
>  #endif
> 
>  #define CR0_RESET       0xE0UL
> @@ -199,16 +201,36 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp)
>      CPUS390XState *env = &cpu->env;
>      Error *err = NULL;
> 
> +#if !defined(CONFIG_USER_ONLY)
> +    if (cpu->id >= max_cpus) {
> +        error_setg(errp, "Unable to add CPU: %" PRIi64
> +                   ", max allowed: %d", cpu->id, max_cpus - 1);

not sure if we should report this into err and then to an error_propgate().

> +        return;
> +    }
> +#endif
> +    if (cpu_exists(cpu->id)) {
> +        error_setg(errp, "Unable to add CPU: %" PRIi64
> +                   ", it already exists", cpu->id);

dito

> +        return;
> +    }
> +    if (cpu->id != scc->next_cpu_id) {
> +        error_setg(errp, "Unable to add CPU: %" PRIi64
> +                   ", The next available id is %" PRIi64, cpu->id,
> +                   scc->next_cpu_id);

dito

> +        return;
> +    }
> +
>      cpu_exec_init(cs, &err);
>      if (err != NULL) {
>          error_propagate(errp, err);
>          return;
>      }
> +    scc->next_cpu_id = cs->cpu_index + 1;

Why can't we simply do a scc->next_cpu_id++ as before and leave cs->cpu_index
logic out?

> 
>  #if !defined(CONFIG_USER_ONLY)
>      qemu_register_reset(s390_cpu_machine_reset_cb, cpu);
>  #endif
> -    env->cpu_num = scc->next_cpu_id++;
> +    env->cpu_num = cpu->id;
>      s390_cpu_gdb_init(cs);
>      qemu_init_vcpu(cs);
>  #if !defined(CONFIG_USER_ONLY)
> @@ -220,6 +242,36 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp)
>      scc->parent_realize(dev, errp);
>  }
> 
> +static void s390_cpu_set_id(Object *obj, Visitor *v, const char *name,
> +                            void *opaque, Error **errp)

s/s390_/s390x_/ ?

> +{
> +    S390CPU *cpu = S390_CPU(obj);
> +    DeviceState *dev = DEVICE(obj);
> +    const int64_t min = 0;
> +    const int64_t max = UINT32_MAX;
> +    Error *err = NULL;
> +    int64_t value;
> +
> +    if (dev->realized) {
> +        error_setg(errp, "Attempt to set property '%s' on '%s' after "
> +                   "it was realized", name, object_get_typename(obj));
> +        return;
> +    }
> +
> +    visit_type_int(v, name, &value, &err);
> +    if (err) {
> +        error_propagate(errp, err);
> +        return;
> +    }
> +    if (value < min || value > max) {
> +        error_setg(errp, "Property %s.%s doesn't take value %" PRId64
> +                   " (minimum: %" PRId64 ", maximum: %" PRId64 ")" ,
> +                   object_get_typename(obj), name, value, min, max);
> +        return;
> +    }
> +    cpu->id = value;
> +}
> +
>  static void s390_cpu_initfn(Object *obj)
>  {
>      CPUState *cs = CPU(obj);
> @@ -233,6 +285,8 @@ static void s390_cpu_initfn(Object *obj)
>      cs->env_ptr = env;
>      cs->halted = 1;
>      cs->exception_index = EXCP_HLT;
> +    object_property_add(OBJECT(cpu), "id", "int64_t", NULL, s390_cpu_set_id,
> +                        NULL, NULL, NULL);

Would it be helpful for introspection to also get the id of a cpu?


>  #if !defined(CONFIG_USER_ONLY)
>      qemu_get_timedate(&tm, 0);
>      env->tod_offset = TOD_UNIX_EPOCH +
> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
> index 49c8415..6667cc0 100644
> --- a/target-s390x/cpu.h
> +++ b/target-s390x/cpu.h
> @@ -413,6 +413,8 @@ void trigger_pgm_exception(CPUS390XState *env, uint32_t code, uint32_t ilen);
>  #endif
> 
>  S390CPU *cpu_s390x_init(const char *cpu_model);
> +S390CPU *s390_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);
>  int cpu_s390x_exec(CPUState *cpu);
> 
> diff --git a/target-s390x/helper.c b/target-s390x/helper.c
> index 838bdd9..c48c816 100644
> --- a/target-s390x/helper.c
> +++ b/target-s390x/helper.c
> @@ -30,6 +30,9 @@
>  //#define DEBUG_S390
>  //#define DEBUG_S390_STDOUT
> 
> +/* Use to track cpu ID for linux-user only */
> +static int64_t next_cpu_id;

I think be best use this into the function cpu_s390x_init() then, as this is
only needed to keep linux-user working.

> +
>  #ifdef DEBUG_S390
>  #ifdef DEBUG_S390_STDOUT
>  #define DPRINTF(fmt, ...) \
> @@ -65,14 +68,49 @@ void s390x_cpu_timer(void *opaque)
>  }
>  #endif
> 
> -S390CPU *cpu_s390x_init(const char *cpu_model)
> +S390CPU *cpu_s390x_create(const char *cpu_model, Error **errp)
>  {
>      S390CPU *cpu;
> 
>      cpu = S390_CPU(object_new(TYPE_S390_CPU));
> 
> -    object_property_set_bool(OBJECT(cpu), true, "realized", NULL);
> +    return cpu;
> +}
> +
> +S390CPU *s390_new_cpu(const char *cpu_model, int64_t id, Error **errp)

s/s390_/s390x_/ ?

> +{
> +    S390CPU *cpu = NULL;

No need to initialize cpu.

> +    Error *err = NULL;
> +
> +    cpu = cpu_s390x_create(cpu_model, &err);
> +    if (err != NULL) {
> +        goto out;
> +    }
> +
> +    object_property_set_int(OBJECT(cpu), id, "id", &err);
> +    if (err != NULL) {
> +        goto out;
> +    }
> +    object_property_set_bool(OBJECT(cpu), true, "realized", &err);
> 
> +out:
> +    if (err) {
> +        error_propagate(errp, err);
> +        object_unref(OBJECT(cpu));
> +        cpu = NULL;
> +    }
> +    return cpu;
> +}
> +
> +S390CPU *cpu_s390x_init(const char *cpu_model)
> +{
> +    Error *err = NULL;
> +    S390CPU *cpu;
> +
> +    cpu = s390_new_cpu(cpu_model, next_cpu_id++, &err);
> +    if (err) {
> +        error_report_err(err);
> +    }
>      return cpu;
>  }
> 

This looks like the right way for me. Only minor nits.

David