Re: [PATCH v2 2/3] qdev-properties: Add DEFINE_PROP_ON_OFF_AUTO_BIT64()

[Akihiko Odaki <akihiko.odaki@daynix.com>]

On 2024/10/29 1:50, Daniel P. Berrangé wrote:
> On Tue, Oct 22, 2024 at 01:50:39PM +0900, Akihiko Odaki wrote:
>> DEFINE_PROP_ON_OFF_AUTO_BIT64() corresponds to DEFINE_PROP_ON_OFF_AUTO()
>> as DEFINE_PROP_BIT64() corresponds to DEFINE_PROP_BOOL(). The difference
>> is that DEFINE_PROP_ON_OFF_AUTO_BIT64() exposes OnOffAuto instead of
>> bool.
> 
> Again, same feedback as last time.
> 
> With this design, existing users of DEFINE_PROP_BIT64 that
> get converted to DEFINE_PROP_ON_OFF_AUTO_BIT64, in addition
> to gaining the desired "auto" value, also gain redundant
> 'on' and 'off' values as side-effects.
> 
> In the next patch, the stated problem is that virtio code
> needs to distinguish between bits that are user set, and
> bits that are set based on available host backend features.
> 
> That doesn't seem to require us to accept any new values
> from the user. It should be sufficient to track user
> specified features, separately from user specified values.
> ie when parsing user input for bitfields, we need to parse
> into a pair of fields
> 
>    uint64_t has_user_features;  /* which bits were specified */
>    uint64_t user_features;      /* values of specified bits*/

Properties also have getters. We don't know what to return with them 
without the new value.

Regards,
Akihiko Odaki

> 
>>
>> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
>> ---
>>   include/hw/qdev-properties.h | 18 ++++++++++++
>>   hw/core/qdev-properties.c    | 66 +++++++++++++++++++++++++++++++++++++++++++-
>>   2 files changed, 83 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/hw/qdev-properties.h b/include/hw/qdev-properties.h
>> index 09aa04ca1e27..afec53a48470 100644
>> --- a/include/hw/qdev-properties.h
>> +++ b/include/hw/qdev-properties.h
>> @@ -43,11 +43,22 @@ struct PropertyInfo {
>>       ObjectPropertyRelease *release;
>>   };
>>   
>> +/**
>> + * struct OnOffAutoBit64 - OnOffAuto storage with 64 elements.
>> + * @on_bits: Bitmap of elements with "on".
>> + * @auto_bits: Bitmap of elements with "auto".
>> + */
>> +typedef struct OnOffAutoBit64 {
>> +    uint64_t on_bits;
>> +    uint64_t auto_bits;
>> +} OnOffAutoBit64;
>> +
>>   
>>   /*** qdev-properties.c ***/
>>   
>>   extern const PropertyInfo qdev_prop_bit;
>>   extern const PropertyInfo qdev_prop_bit64;
>> +extern const PropertyInfo qdev_prop_on_off_auto_bit64;
>>   extern const PropertyInfo qdev_prop_bool;
>>   extern const PropertyInfo qdev_prop_enum;
>>   extern const PropertyInfo qdev_prop_uint8;
>> @@ -100,6 +111,13 @@ extern const PropertyInfo qdev_prop_link;
>>                   .set_default = true,                              \
>>                   .defval.u  = (bool)_defval)
>>   
>> +#define DEFINE_PROP_ON_OFF_AUTO_BIT64(_name, _state, _field, _bit, _defval) \
>> +    DEFINE_PROP(_name, _state, _field, qdev_prop_on_off_auto_bit64,         \
>> +                OnOffAutoBit64,                                             \
>> +                .bitnr    = (_bit),                                         \
>> +                .set_default = true,                                        \
>> +                .defval.i = (OnOffAuto)_defval)
>> +
>>   #define DEFINE_PROP_BOOL(_name, _state, _field, _defval)     \
>>       DEFINE_PROP(_name, _state, _field, qdev_prop_bool, bool, \
>>                   .set_default = true,                         \
>> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
>> index f0a270bb4f61..cc76ff0dfae6 100644
>> --- a/hw/core/qdev-properties.c
>> +++ b/hw/core/qdev-properties.c
>> @@ -187,7 +187,8 @@ const PropertyInfo qdev_prop_bit = {
>>   
>>   static uint64_t qdev_get_prop_mask64(Property *prop)
>>   {
>> -    assert(prop->info == &qdev_prop_bit64);
>> +    assert(prop->info == &qdev_prop_bit64 ||
>> +           prop->info == &qdev_prop_on_off_auto_bit64);
>>       return 0x1ull << prop->bitnr;
>>   }
>>   
>> @@ -232,6 +233,69 @@ const PropertyInfo qdev_prop_bit64 = {
>>       .set_default_value = set_default_value_bool,
>>   };
>>   
>> +static void prop_get_on_off_auto_bit64(Object *obj, Visitor *v,
>> +                                       const char *name, void *opaque,
>> +                                       Error **errp)
>> +{
>> +    Property *prop = opaque;
>> +    OnOffAutoBit64 *p = object_field_prop_ptr(obj, prop);
>> +    int value;
>> +    uint64_t mask = qdev_get_prop_mask64(prop);
>> +
>> +    if (p->auto_bits & mask) {
>> +        value = ON_OFF_AUTO_AUTO;
>> +    } else if (p->on_bits & mask) {
>> +        value = ON_OFF_AUTO_ON;
>> +    } else {
>> +        value = ON_OFF_AUTO_OFF;
>> +    }
>> +
>> +    visit_type_enum(v, name, &value, &OnOffAuto_lookup, errp);
>> +}
>> +
>> +static void prop_set_on_off_auto_bit64(Object *obj, Visitor *v,
>> +                                       const char *name, void *opaque,
>> +                                       Error **errp)
>> +{
>> +    Property *prop = opaque;
>> +    OnOffAutoBit64 *p = object_field_prop_ptr(obj, prop);
>> +    bool bool_value;
>> +    int value;
>> +    uint64_t mask = qdev_get_prop_mask64(prop);
>> +
>> +    if (visit_type_bool(v, name, &bool_value, NULL)) {
>> +        value = bool_value ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
>> +    } else if (!visit_type_enum(v, name, &value, &OnOffAuto_lookup, errp)) {
>> +        return;
>> +    }
>> +
>> +    switch (value) {
>> +    case ON_OFF_AUTO_AUTO:
>> +        p->on_bits &= ~mask;
>> +        p->auto_bits |= mask;
>> +        break;
>> +
>> +    case ON_OFF_AUTO_ON:
>> +        p->on_bits |= mask;
>> +        p->auto_bits &= ~mask;
>> +        break;
>> +
>> +    case ON_OFF_AUTO_OFF:
>> +        p->on_bits &= ~mask;
>> +        p->auto_bits &= ~mask;
>> +        break;
>> +    }
>> +}
>> +
>> +const PropertyInfo qdev_prop_on_off_auto_bit64 = {
>> +    .name  = "OnOffAuto",
>> +    .description = "on/off/auto",
>> +    .enum_table = &OnOffAuto_lookup,
>> +    .get = prop_get_on_off_auto_bit64,
>> +    .set = prop_set_on_off_auto_bit64,
>> +    .set_default_value = qdev_propinfo_set_default_value_enum,
>> +};
>> +
>>   /* --- bool --- */
>>   
>>   static void get_bool(Object *obj, Visitor *v, const char *name, void *opaque,
>>
>> -- 
>> 2.47.0
>>
>>
> 
> With regards,
> Daniel