Re: [PATCH v2 2/2] domain: expose newly introduced hypercalls as XENFEAT

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 06/10/2023 2:00 pm, Roger Pau Monne wrote:
> diff --git a/xen/include/public/features.h b/xen/include/public/features.h
> index d2a9175aae67..22713a51b520 100644
> --- a/xen/include/public/features.h
> +++ b/xen/include/public/features.h
> @@ -111,6 +111,15 @@
>  #define XENFEAT_not_direct_mapped         16
>  #define XENFEAT_direct_mapped             17
>  
> +/*
> + * Signal whether the domain is permitted to use the following hypercalls:
> + *
> + * VCPUOP_register_runstate_phys_area
> + * VCPUOP_register_vcpu_time_phys_area
> + */
> +#define XENFEAT_runstate_phys_area     18
> +#define XENFEAT_vcpu_time_phys_area    19
> +
>  #define XENFEAT_NR_SUBMAPS 1
>  
>  #endif /* __XEN_PUBLIC_FEATURES_H__ */
> diff --git a/xen/include/public/vcpu.h b/xen/include/public/vcpu.h
> index 8fb0bd1b6c03..03b031a3e557 100644
> --- a/xen/include/public/vcpu.h
> +++ b/xen/include/public/vcpu.h
> @@ -236,6 +236,9 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_register_time_memory_area_t);
>   * Note that the area registered via VCPUOP_register_runstate_memory_area 
> will
>   * be updated in the same manner as the one registered via virtual address 
> PLUS
>   * VMASST_TYPE_runstate_update_flag engaged by the domain.
> + *
> + * XENFEAT_{runstate,vcpu_time}_phys_area feature bits signal if the domain 
> is
> + * permitted the usage of the hypercalls.
>   */
>  #define VCPUOP_register_runstate_phys_area      14
>  #define VCPUOP_register_vcpu_time_phys_area     15

For both of these, I'd suggest s/permitted/able/.  For older versions of
Xen which don't advertise the XENFEAT, it's a matter of capability, not
permission.

Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> and
I'm happy to adjust on commit to save sending out a v3.

Thanks,

~Andrew