Re: [RFC 7/9] target/arm: Add CPU features to query-cpu-model-expansion

[Andrew Jones]

On Thu, Aug 13, 2020 at 06:26:55PM +0800, Peng Liang wrote:
> Add CPU features to the result of query-cpu-model-expansion so that
> other applications (such as libvirt) can know the supported CPU
> features.
> 
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Signed-off-by: Peng Liang <liangpeng10@huawei.com>
> ---
>  target/arm/cpu.c     | 41 +++++++++++++++++++++++++++++++++++++++++
>  target/arm/cpu.h     |  2 ++
>  target/arm/monitor.c |  2 ++
>  3 files changed, 45 insertions(+)
> 
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index 3fc54cb3a4..0f620e8afe 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -25,6 +25,8 @@
>  #include "qemu/module.h"
>  #include "qapi/error.h"
>  #include "qapi/visitor.h"
> +#include "qapi/qmp/qdict.h"
> +#include "qom/qom-qobject.h"
>  #include "cpu.h"
>  #include "internals.h"
>  #include "exec/exec-all.h"
> @@ -1515,6 +1517,45 @@ static const CPUFeatureDep feature_dependencies[] = {
>      },
>  };
>  
> +static char *strtolower(char *src)
> +{
> +    char *start = src;
> +
> +    for (; *src; ++src) {
> +        *src = tolower(*src);
> +    }
> +
> +    return start;
> +}

Shouldn't need this. The CPU property names should already be lowercase.

> +
> +void arm_cpu_features_to_dict(ARMCPU *cpu, QDict *features)
> +{
> +    Object *obj = OBJECT(cpu);
> +    const char *name;
> +    ObjectProperty *prop;
> +    bool is_32bit = !arm_feature(&cpu->env, ARM_FEATURE_AARCH64);
> +    int i;
> +
> +    for (i = 0; i < ARRAY_SIZE(cpu_features); ++i) {
> +        if (is_32bit != cpu_features[i].is_32bit) {
> +            continue;
> +        }
> +
> +        name = cpu_features[i].name;
> +        prop = object_property_find(obj, name, NULL);
> +        if (prop) {
> +            QObject *value;
> +            g_autofree char *tmp;
> +
> +            assert(prop->get);
> +            value = object_property_get_qobject(obj, name, &error_abort);
> +            tmp = strtolower(g_strdup(name));
> +
> +            qdict_put_obj(features, tmp, value);
> +        }
> +    }
> +}
> +
>  static void arm_cpu_get_bit_prop(Object *obj, Visitor *v, const char *name,
>                                   void *opaque, Error **errp)
>  {
> diff --git a/target/arm/cpu.h b/target/arm/cpu.h
> index 5d8074d03b..da68b7f8f4 100644
> --- a/target/arm/cpu.h
> +++ b/target/arm/cpu.h
> @@ -3933,4 +3933,6 @@ static inline bool isar_feature_any_tts2uxn(const 
> ARMISARegisters *id)
>  #define cpu_isar_feature(name, cpu) \
>      ({ ARMCPU *cpu_ = (cpu); isar_feature_##name(&cpu_->isar); })
>  
> +void arm_cpu_features_to_dict(ARMCPU *cpu, QDict *features);
> +
>  #endif
> diff --git a/target/arm/monitor.c b/target/arm/monitor.c
> index ba6e01abd0..f8eb29efec 100644
> --- a/target/arm/monitor.c
> +++ b/target/arm/monitor.c
> @@ -225,6 +225,8 @@ CpuModelExpansionInfo 
> *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
>          }
>      }
>  
> +    arm_cpu_features_to_dict(ARM_CPU(obj), qdict_out);

Since nobody is looking for these features in qdict_in, then none
of these features can be changed by QMP user. How does the QMP
user probe whether or not the feature will work when enabled?

Thanks,
drew

> +
>      if (!qdict_size(qdict_out)) {
>          qobject_unref(qdict_out);
>      } else {
> -- 
> 2.18.4
>