Re: Warnings `Could not retrieve perf counters (-19)` and `amd_pstate: the _CPC object is not present in SBIOS or ACPI disabled` (Dell PowerEdge R7625, AMD EPYC 9174F)

[Paul Menzel <pmenzel@molgen.mpg.de>]

Dear Linux folks,


Am 28.01.25 um 16:08 schrieb Paul Menzel:
> [Cc: +x86 maintainers and ACPI list]

> Am 28.01.25 um 11:49 schrieb Paul Menzel:
> 
>> Thank you for your quick replies. Gautham, messages with HTML are 
>> rejected by Linux kernel lists.
>>
>>
>> Am 28.01.25 um 04:51 schrieb Shenoy, Gautham Ranjal:
>>
>>> As Mario mentioned, you need to enable the CPPC option. Looking for 
>>> some of the Dell PowerEdge documentation, there is an option called 
>>> "Collaborative CPU Performance Control" (https://www.dell.com/ 
>>> support/manuals/en-in/poweredge-r730/r730_ompublication/system- 
>>> profile-settings-details?guid=guid-2e9b46a1-71e3-4072-9d86- 
>>> db648757f0e6&lang=en-us).
>>>
>>> [cid:fe57df8f-3d99-4ea0-8f6e-b0daae49bb0e]
>>> Can you please try enabling it ?
>>
>> You quoted the Dell PowerEdge R730. I couldn’t find it in the *Dell 
>> PowerEdge R7625 Installation and Service Manual* [1], and also it’s 
>> not listed in the iDRAC9 Web site (attached with added `.txt` 
>> extension to trick the Linux list).
> 
> The amd_pstate warning seems to be related to the perf counters warning 
> Linux prints earlier:
> 
>      $ dmesg --level alert,crit,err,warn
>      [    2.666393] Spectre V2 : WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!
>      [    8.109446] Could not retrieve perf counters (-19)
>      [    9.386551] scsi 0:0:4:0: set ignore_delay_remove for handle(0x0012)
>      [    9.487804] amd_pstate: the _CPC object is not present in SBIOS or ACPI disabled
>      [   14.726193] wmi_bus wmi_bus-PNP0C14:00: [Firmware Bug]: WQBC data block query control method not found
> 
> x86 maintainers, the original report with the Linux logs attached is in 
> the archive [3].
> 
> It looks like, there is something missing in the Dell firmware to enable 
> the feature.
> 
> The perf counters warning is from `amd_set_max_freq_ratio()` in `arch/ 
> x86/kernel/acpi/cppc.c`:
> 
> ```
> static void amd_set_max_freq_ratio(void)
> {
>          struct cppc_perf_caps perf_caps;
>          u64 numerator, nominal_perf;
>          u64 perf_ratio;
>          int rc;
> 
>          rc = cppc_get_perf_caps(0, &perf_caps);
>          if (rc) {
>                  pr_warn("Could not retrieve perf counters (%d)\n", rc);
>                  return;
>          }
>          […]
> }
> ```
> 
> With
> 
>      include/uapi/asm-generic/errno-base.h:#define    ENODEV        19    /* No such device */
> 
> this is returned by in `drivers/acpi/cppc_acpi.c`:
> 
> ```
> /**
>   * cppc_get_perf_caps - Get a CPU's performance capabilities.
>   * @cpunum: CPU from which to get capabilities info.
>   * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h
>   *
>   * Return: 0 for success with perf_caps populated else -ERRNO.
>   */
> int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
> {
>          struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
>          […]
>          if (!cpc_desc) {
>                  pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
>                  return -ENODEV;
>          }
>          […]
> }
> ```

@AMD folks, just for clarity. Did Dell something with their firmware? If 
so, are you going to work with Dell on a solution, or do I need to 
report the issue to them?


Kind regards,

Paul


>> PS:
>>
>>> -- 
>>>
>>> Thanks and Regards
>>>
>>> Gautham.
>>
>> Only if you care: Your signature delimiter misses a space at the end [2].
>>
>>
>> [1]: https://www.dell.com/support/manuals/de-de/poweredge-r7625/per7625_ism_pub/system-profile-settings?guid=guid-9f6b6652-4079-45e7-90f5-1c8feee08ec0&lang=en-us
>> [2]: https://en.wikipedia.org/wiki/Signature_block#Standard_delimiter
> [3]: https://lore.kernel.org/linux-pm/d09f52d8-e084-4875-9608-5b3db2554f3d@molgen.mpg.de/T/#t