Re: [PATCH v2 21/21] hw/core/qdev-properties: support valid default value for DEFINE_PROP_UINT64_CHECKMASK

["Chen, Zide" <zide.chen@intel.com>]

On 2/9/2026 7:23 PM, Zhao Liu wrote:
> DEFINE_PROP_UINT64_CHECKMASK is designed to detect and check user's
> property setting:
>  * checking: check property value against a bitmask.
>  * detection: ask caller to provide an invalid value as the initial
>      "sentinel" value, which is impossible to be set by users. However,
>      this detection is not strict, since the property could be also
>      set internally.
> 
> The entire mechanism is not easy to use.
> 
> Now there's USER_SET flag in place (and the current unique use case
> "lbr-fmt" has been converted to checking USER_SET way), manual setting
> of invalid initial values is no longer required.
> 
> Thus, extend DEFINE_PROP_UINT64_CHECKMASK to support *valid* default
> value, and for "lbr-fmt" case, replace the invalid initialization value
> `~PERF_CAP_LBR_FMT` with a valid value `0`.
> 
> In addition, considering DEFINE_PROP_UINT64_CHECKMASK itself actually
> doesn't identify whether the property is set by the user or not, remove
> "user-supplied" related description in its document.
> 
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---

Nice to see "cpu->lbr_fmt = ~PERF_CAP_LBR_FMT" is gone.

Reviewed-by: Zide Chen <zide.chen@intel.com>

>  hw/core/qdev-properties.c         |  1 +
>  include/hw/core/qdev-properties.h | 14 +++++++-------
>  target/i386/cpu.c                 |  4 +---
>  3 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> index 91c4010e7dc9..b84214e60f19 100644
> --- a/hw/core/qdev-properties.c
> +++ b/hw/core/qdev-properties.c
> @@ -507,6 +507,7 @@ const PropertyInfo qdev_prop_uint64_checkmask = {
>      .type  = "uint64",
>      .get   = get_uint64,
>      .set   = set_uint64_checkmask,
> +    .set_default_value = qdev_propinfo_set_default_value_uint,
>  };
>  
>  /* --- pointer-size integer --- */
> diff --git a/include/hw/core/qdev-properties.h b/include/hw/core/qdev-properties.h
> index c06de37b1e9d..2ac784bb5e9c 100644
> --- a/include/hw/core/qdev-properties.h
> +++ b/include/hw/core/qdev-properties.h
> @@ -128,14 +128,14 @@ extern const PropertyInfo qdev_prop_link;
>                  ##__VA_ARGS__)
>  
>  /**
> - * The DEFINE_PROP_UINT64_CHECKMASK macro checks a user-supplied value
> - * against corresponding bitmask, rejects the value if it violates.
> - * The default value is set in instance_init().
> + * The DEFINE_PROP_UINT64_CHECKMASK macro checks a value against corresponding
> + * bitmask, rejects the value if it violates.
>   */
> -#define DEFINE_PROP_UINT64_CHECKMASK(_name, _state, _field, _bitmask)   \
> -    DEFINE_PROP(_name, _state, _field, qdev_prop_uint64_checkmask, uint64_t, \
> -                .bitmask    = (_bitmask),                     \
> -                .set_default = false)
> +#define DEFINE_PROP_UINT64_CHECKMASK(_name, _state, _field, _bitmask, _defval) \
> +    DEFINE_PROP(_name, _state, _field, qdev_prop_uint64_checkmask, uint64_t,   \
> +                .bitmask    = (_bitmask),                                      \
> +                .set_default = true,                                           \
> +                .defval.u    = (_defval))
>  
>  /**
>   * DEFINE_PROP_ARRAY:
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index a6d943c53a3f..56735570d66c 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -10265,9 +10265,7 @@ static void x86_cpu_initfn(Object *obj)
>      object_property_add_alias(obj, "pause_filter", obj, "pause-filter");
>      object_property_add_alias(obj, "sse4_1", obj, "sse4.1");
>      object_property_add_alias(obj, "sse4_2", obj, "sse4.2");
> -
>      object_property_add_alias(obj, "hv-apicv", obj, "hv-avic");
> -    cpu->lbr_fmt = ~PERF_CAP_LBR_FMT;
>      object_property_add_alias(obj, "lbr_fmt", obj, "lbr-fmt");
>  
>      if (xcc->model) {
> @@ -10439,7 +10437,7 @@ static const Property x86_cpu_properties[] = {
>  #endif
>      DEFINE_PROP_INT32("node-id", X86CPU, node_id, CPU_UNSET_NUMA_NODE_ID),
>      DEFINE_PROP_BOOL("pmu", X86CPU, enable_pmu, false),
> -    DEFINE_PROP_UINT64_CHECKMASK("lbr-fmt", X86CPU, lbr_fmt, PERF_CAP_LBR_FMT),
> +    DEFINE_PROP_UINT64_CHECKMASK("lbr-fmt", X86CPU, lbr_fmt, PERF_CAP_LBR_FMT, 0),
>  
>      DEFINE_PROP_UINT32("hv-spinlocks", X86CPU, hyperv_spinlock_attempts,
>                         HYPERV_SPINLOCK_NEVER_NOTIFY),