Re: [PATCH v3 1/2] qdev-properties: Add a new macro to validate bitmask for setter

[Markus Armbruster]

Like Xu <like.xu@linux.intel.com> writes:

> The new generic DEFINE_PROP_BITMASK_UINT64 could be used to ensure
> that a user-provided property value complies with its bitmask rule
> and the default value is recommended to be set in instance_init().
>
> Signed-off-by: Like Xu <like.xu@linux.intel.com>
> ---
>  hw/core/qdev-properties.c    | 19 +++++++++++++++++++
>  include/hw/qdev-properties.h | 12 ++++++++++++
>  include/qapi/qmp/qerror.h    |  3 +++
>  3 files changed, 34 insertions(+)
>
> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> index 50f40949f5..3784d3b30d 100644
> --- a/hw/core/qdev-properties.c
> +++ b/hw/core/qdev-properties.c
> @@ -428,6 +428,25 @@ const PropertyInfo qdev_prop_int64 = {
>      .set_default_value = qdev_propinfo_set_default_value_int,
>  };
>  
> +static void set_bitmask_uint64(Object *obj, Visitor *v, const char *name,
> +                      void *opaque, Error **errp)
> +{
> +    Property *prop = opaque;
> +    uint64_t *ptr = object_field_prop_ptr(obj, prop);
> +
> +    visit_type_uint64(v, name, ptr, errp);
> +
> +    if (*ptr & ~prop->bitmask) {
> +        error_setg(errp, QERR_INVALID_BITMASK_VALUE, name, prop->bitmask);
> +    }
> +}
> +
> +const PropertyInfo qdev_prop_bitmask_uint64 = {
> +    .name  = "int64",
> +    .get   = get_uint64,
> +    .set   = set_bitmask_uint64,
> +};
> +
>  /* --- string --- */
>  
>  static void release_string(Object *obj, const char *name, void *opaque)
> diff --git a/include/hw/qdev-properties.h b/include/hw/qdev-properties.h
> index 0ef97d60ce..42f0112e14 100644
> --- a/include/hw/qdev-properties.h
> +++ b/include/hw/qdev-properties.h
> @@ -17,6 +17,7 @@ struct Property {
>      const PropertyInfo *info;
>      ptrdiff_t    offset;
>      uint8_t      bitnr;
> +    uint64_t     bitmask;

The new member is used just for BITMASK properties.  Similar to how
.bitnr is used just for BIT properties, .link_type is just for LINK
properties, and the .arrayFOO are just for ARRAY properties.  I don't
like that, to be frank, but I'm not the maintainer.

>      bool         set_default;
>      union {
>          int64_t i;
> @@ -53,6 +54,7 @@ extern const PropertyInfo qdev_prop_uint16;
>  extern const PropertyInfo qdev_prop_uint32;
>  extern const PropertyInfo qdev_prop_int32;
>  extern const PropertyInfo qdev_prop_uint64;
> +extern const PropertyInfo qdev_prop_bitmask_uint64;
>  extern const PropertyInfo qdev_prop_int64;
>  extern const PropertyInfo qdev_prop_size;
>  extern const PropertyInfo qdev_prop_string;
> @@ -102,6 +104,16 @@ extern const PropertyInfo qdev_prop_link;
>                  .set_default = true,                         \
>                  .defval.u    = (bool)_defval)
>  
> +/**
> + * The DEFINE_PROP_BITMASK_UINT64 could be used to ensure that
> + * a user-provided value complies with certain bitmask rule and
> + * the default value is recommended to be set in instance_init().
> + */
> +#define DEFINE_PROP_BITMASK_UINT64(_name, _state, _field, _bitmask)   \
> +    DEFINE_PROP(_name, _state, _field, qdev_prop_bitmask_uint64, uint64_t, \
> +                .bitmask    = (_bitmask),                     \
> +                .set_default = false)
> +
>  #define PROP_ARRAY_LEN_PREFIX "len-"
>  
>  /**
> diff --git a/include/qapi/qmp/qerror.h b/include/qapi/qmp/qerror.h
> index 596fce0c54..aab7902760 100644
> --- a/include/qapi/qmp/qerror.h
> +++ b/include/qapi/qmp/qerror.h
> @@ -68,4 +68,7 @@
>  #define QERR_UNSUPPORTED \
>      "this feature or command is not currently supported"
>  
> +#define QERR_INVALID_BITMASK_VALUE \
> +    "the requested value for '%s' violates its bitmask '0x%lx'"
> +
>  #endif /* QERROR_H */

Note the comment further up:

   /*
    * These macros will go away, please don't use in new code, and do not
    * add new ones!
    */

Please put the error message string into set_bitmask_uint64()'s
error_setg() call instead.