Re: [RFC PATCH v2 23/29] target/arm/qmp: add query-arm-cpu-props-info

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Jun 05, 2026 at 08:33:52AM +0000, Khushit Shah wrote:
> Introduce 'query-arm-cpu-props-info' QMP command. This command returns
> information about ARM CPU model properties, including their name, type,
> supported values on the given host, and composite parent if any.

Do we have to make this ARM only ?

x86 has named CPU properties too. They are all basically
booleans so this API offers a superset of functionality
needed for x86, and thus I'd expect x86 to be folded into
this new API too.

> This provides management layer necessary information to determine
> migration compatibility off a VM on different host.
> 
> Signed-off-by: Khushit Shah <khushit.shah@nutanix.com>
> ---
>  qapi/misc-arm.json              | 41 ++++++++++++++++
>  stubs/qmp-arm-gic.c             |  6 +++
>  target/arm/arm-cpu-props-stub.c | 13 +++++
>  target/arm/arm-cpu-props.c      | 85 +++++++++++++++++++++++++++++++++
>  target/arm/arm-cpu-props.h      |  5 ++
>  target/arm/arm-qmp-cmds.c       | 44 +++++++++++++++++
>  target/arm/cpu-idregs.c         | 71 +++++++++++++++++++++++++++
>  target/arm/cpu-idregs.h         |  8 ++++
>  8 files changed, 273 insertions(+)
> 
> diff --git a/qapi/misc-arm.json b/qapi/misc-arm.json
> index 4dc66d00e5..1a3fb140c4 100644
> --- a/qapi/misc-arm.json
> +++ b/qapi/misc-arm.json
> @@ -46,6 +46,47 @@
>  ##
>  { 'command': 'query-gic-capabilities', 'returns': ['GICCapability'] }
>  
> +##
> +# @CpuPropInfo:
> +#
> +# Information about a specific ARM CPU model property.
> +#
> +# @name: the name of the property
> +#
> +# @type: the type of the property, any of ('string', 'boolean',
> +#     'number').
> +#
> +# @supported-values: the set of values the host hardware supports
> +#     for the property, a list of strings.
> +#
> +# @composite: name of the encapsulating composite property if any.
> +#
> +# Since: 11.1
> +##
> +{ 'struct': 'CpuPropInfo',
> +  'data': { 'name': 'str',
> +            'type': 'str',

This should be an enumerated type, not a string.

> +            'supported-values': 'any',

If these values vary based on @type, then this should
be a discriminated union.

> +            '*composite': 'str' } }
> +

With regards,
Daniel
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