[Bug 219431] [6.12] amd-pstate / Ryzen 5xxx (Zen 3, Vermeer): Could not retrieve highest performance (-19)

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=219431

--- Comment #13 from Mario Limonciello (AMD) (mario.limonciello@amd.com) ---
> I suspect the answer is yes.

Actually; no it should be new, but it's because the frequency calculation was
wrong before.

I found a system with shared mem and I have a theory what's going on is that
frequency invariance is attempting to get setup before all CPUs have probed.

Before the preferred cores code frequency invariance would be calculated from
the first CPU only as _CPC is probed.  But with preferred cores code in place
you need ALL _CPC values present to know whether you have preferred cores or
not.

I added some dump stack calls to acpi_cppc_processor_probe when the struct is
parsed:

ACPI CPPC: Parsed CPC struct for CPU: 0
CPU: 0 UID: 0 PID: 23 Comm: cpuhp/0 Not tainted 6.12.0-rc5-00026-g0c7b883226dd
#268
Hardware name: LENOVO 30E1S68903/1046, BIOS S07KT5BA 01/26/2024
Call Trace:
 <TASK>
 dump_stack_lvl+0x60/0x80
 acpi_cppc_processor_probe+0x9fc/0xe50
 acpi_soft_cpu_online+0x69/0x160
 ? __pfx_acpi_soft_cpu_online+0x10/0x10
 cpuhp_invoke_callback+0x308/0x4c0
 ? srso_return_thunk+0x5/0x5f
 ? __pfx_smpboot_thread_fn+0x10/0x10
 cpuhp_thread_fun+0x131/0x210
 smpboot_thread_fn+0x187/0x220
 kthread+0xdd/0x110
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x30/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Then I added one to the error sequence.

ACPI CPPC: No CPC descriptor for CPU:1
CPU: 0 UID: 0 PID: 23 Comm: cpuhp/0 Not tainted 6.12.0-rc5-00026-g0c7b883226dd
#268
Hardware name: LENOVO 30E1S68903/1046, BIOS S07KT5BA 01/26/2024
Call Trace:
 <TASK>
 dump_stack_lvl+0x60/0x80
 cppc_get_perf+0x127/0x1c0
 amd_get_highest_perf+0x5e/0x80
 amd_detect_prefcore+0x7a/0x130
 amd_get_boost_ratio_numerator+0x28/0x90
 init_freq_invariance_cppc+0xad/0x140
 acpi_cppc_processor_probe+0x7ce/0xe50
 acpi_soft_cpu_online+0x69/0x160
 ? __pfx_acpi_soft_cpu_online+0x10/0x10
 cpuhp_invoke_callback+0x308/0x4c0
 ? srso_return_thunk+0x5/0x5f
 ? __pfx_smpboot_thread_fn+0x10/0x10
 cpuhp_thread_fun+0x131/0x210
 smpboot_thread_fn+0x187/0x220
 kthread+0xdd/0x110
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x30/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Could not retrieve highest performance (-19)

You can see that in both cases the code runs on CPU0.  So it's trying to get
values that won't be initialized until CPU1 is ready.

I think this will help "prevent" the error from coming up:

diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
index 5e9325273a9fb..a21c26d1fe65a 100644
--- a/arch/x86/kernel/acpi/cppc.c
+++ b/arch/x86/kernel/acpi/cppc.c
@@ -190,7 +190,7 @@ int amd_detect_prefcore(bool *detected)
                break;
        }

-       for_each_present_cpu(cpu) {
+       for_each_online_cpu(cpu) {
                u32 tmp;
                int ret;

But it's going to probably break preferred cores detection, so it's not a
correct solution.

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