On 28.08.2025 08:54, Penny, Zheng wrote:
> [Public]
>
>> -----Original Message-----
>> From: Jan Beulich <jbeul...@suse.com>
>> Sent: Thursday, August 28, 2025 2:38 PM
>> To: Penny, Zheng <penny.zh...@amd.com>
>> Cc: Huang, Ray <ray.hu...@amd.com>; Anthony PERARD
>> <anthony.per...@vates.tech>; Andrew Cooper <andrew.coop...@citrix.com>;
>> Orzel, Michal <michal.or...@amd.com>; Julien Grall <jul...@xen.org>; Roger
>> Pau
>> Monné <roger....@citrix.com>; Stefano Stabellini <sstabell...@kernel.org>;
>> xen-
>> de...@lists.xenproject.org
>> Subject: Re: [PATCH v7 13/13] xen/cpufreq: Adapt SET/GET_CPUFREQ_CPPC
>> xen_sysctl_pm_op for amd-cppc driver
>>
>> On 28.08.2025 08:35, Jan Beulich wrote:
>>> On 28.08.2025 06:06, Penny, Zheng wrote:
>>>>> -----Original Message-----
>>>>> From: Jan Beulich <jbeul...@suse.com>
>>>>> Sent: Tuesday, August 26, 2025 12:03 AM
>>>>>
>>>>> On 22.08.2025 12:52, Penny Zheng wrote:
>>>>>> --- a/xen/include/public/sysctl.h
>>>>>> +++ b/xen/include/public/sysctl.h
>>>>>> @@ -336,8 +336,14 @@ struct xen_ondemand {
>>>>>> uint32_t up_threshold;
>>>>>> };
>>>>>>
>>>>>> +#define CPUFREQ_POLICY_UNKNOWN 0
>>>>>> +#define CPUFREQ_POLICY_POWERSAVE 1
>>>>>> +#define CPUFREQ_POLICY_PERFORMANCE 2
>>>>>> +#define CPUFREQ_POLICY_ONDEMAND 3
>>>>>
>>>>> Without XEN_ prefixes they shouldn't appear in a public header. But
>>>>> do we need ...
>>>>>
>>>>>> struct xen_get_cppc_para {
>>>>>> /* OUT */
>>>>>> + uint32_t policy; /* CPUFREQ_POLICY_xxx */
>>>>>
>>>>> ... the new field at all? Can't you synthesize the kind-of-governor
>>>>> into struct xen_get_cpufreq_para's respective field? You invoke both
>>>>> sub-ops from xenpm now anyway ...
>>>>>
>>>>
>>>> Maybe I could borrow governor field to indicate policy info, like the
>>>> following in
>> print_cpufreq_para(), then we don't need to add the new filed "policy"
>>>> ```
>>>> + /* Translate governor info to policy info in CPPC active mode */
>>>> + if ( is_cppc_active )
>>>> + {
>>>> + if ( !strncmp(p_cpufreq->u.s.scaling_governor,
>>>> + "ondemand", CPUFREQ_NAME_LEN) )
>>>> + printf("cppc policy : ondemand\n");
>>>> + else if ( !strncmp(p_cpufreq->u.s.scaling_governor,
>>>> + "performance", CPUFREQ_NAME_LEN) )
>>>> + printf("cppc policy : performance\n");
>>>> +
>>>> + else if ( !strncmp(p_cpufreq->u.s.scaling_governor,
>>>> + "powersave", CPUFREQ_NAME_LEN) )
>>>> + printf("cppc policy : powersave\n");
>>>> + else
>>>> + printf("cppc policy : unknown\n");
>>>> + }
>>>> +
>>>> ```
>>>
>>> Something like this is what I was thinking of, yes.
>>
>> Albeit - why the complicated if/else sequence? Why not simply print the
>> field the
>> hypercall returned?
>
> userspace governor doesn't have according policy. I could simplify it to
> ```
> if ( !strncmp(p_cpufreq->u.s.scaling_governor,
> "userspace", CPUFREQ_NAME_LEN) )
> printf("policy : unknown\n");
> else
> printf("policy : %s\n",
> p_cpufreq->u.s.scaling_governor);
> ```
But the hypervisor shouldn't report back "userspace" when the CPPC driver
is in use. ANd I think the tool is okay to trust the hypervisor.
Jan
