Re: [PATCH v3 01/15] xen/cpufreq: introduces XEN_PM_PSD for solely delivery of _PSD

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.03.2025 09:39, Penny Zheng wrote:
> --- a/xen/include/public/platform.h
> +++ b/xen/include/public/platform.h
> @@ -363,12 +363,12 @@ DEFINE_XEN_GUEST_HANDLE(xenpf_getidletime_t);
>  #define XEN_PM_PX   1
>  #define XEN_PM_TX   2
>  #define XEN_PM_PDC  3
> +#define XEN_PM_PSD  4
>  
>  /* Px sub info type */
>  #define XEN_PX_PCT   1
>  #define XEN_PX_PSS   2
>  #define XEN_PX_PPC   4
> -#define XEN_PX_PSD   8
>  
>  struct xen_power_register {
>      uint32_t     space_id;
> @@ -439,6 +439,7 @@ struct xen_psd_package {
>      uint64_t coord_type;
>      uint64_t num_processors;
>  };
> +typedef struct xen_psd_package xen_psd_package_t;
>  
>  struct xen_processor_performance {
>      uint32_t flags;     /* flag for Px sub info type */
> @@ -447,12 +448,6 @@ struct xen_processor_performance {
>      struct xen_pct_register status_register;
>      uint32_t state_count;     /* total available performance states */
>      XEN_GUEST_HANDLE(xen_processor_px_t) states;
> -    struct xen_psd_package domain_info;
> -    /* Coordination type of this processor */
> -#define XEN_CPUPERF_SHARED_TYPE_HW   1 /* HW does needed coordination */
> -#define XEN_CPUPERF_SHARED_TYPE_ALL  2 /* All dependent CPUs should set freq 
> */
> -#define XEN_CPUPERF_SHARED_TYPE_ANY  3 /* Freq can be set from any dependent 
> CPU */
> -    uint32_t shared_type;
>  };
>  typedef struct xen_processor_performance xen_processor_performance_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_processor_performance_t);
> @@ -463,9 +458,15 @@ struct xenpf_set_processor_pminfo {
>      uint32_t type;  /* {XEN_PM_CX, XEN_PM_PX} */
>      union {
>          struct xen_processor_power          power;/* Cx: _CST/_CSD */
> -        struct xen_processor_performance    perf; /* Px: _PPC/_PCT/_PSS/_PSD 
> */
> +        xen_psd_package_t                   domain_info; /* _PSD */
> +        struct xen_processor_performance    perf; /* Px: _PPC/_PCT/_PSS/ */
>          XEN_GUEST_HANDLE(uint32)            pdc;  /* _PDC */
>      } u;
> +    /* Coordination type of this processor */
> +#define XEN_CPUPERF_SHARED_TYPE_HW   1 /* HW does needed coordination */
> +#define XEN_CPUPERF_SHARED_TYPE_ALL  2 /* All dependent CPUs should set freq 
> */
> +#define XEN_CPUPERF_SHARED_TYPE_ANY  3 /* Freq can be set from any dependent 
> CPU */
> +    uint32_t shared_type;
>  };
>  typedef struct xenpf_set_processor_pminfo xenpf_set_processor_pminfo_t;
>  DEFINE_XEN_GUEST_HANDLE(xenpf_set_processor_pminfo_t);

With this change to stable hypercall structures, how is an older Dom0 kernel
going to be able to properly upload the necessary data? IOW: No, you can't
alter existing stable hypercall structures like this.

Jan