This is a note to let you know that I've just added the patch titled ACPI: CPPC: Check present CPUs for determining _CPC is valid to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: acpi-cppc-check-present-cpus-for-determining-_cpc-is.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 34a5b49d40b9d235a55db22dc76e1b88f2338210 Author: Mario Limonciello <mario.limonciello@xxxxxxx> Date: Fri Dec 24 09:04:58 2021 +0800 ACPI: CPPC: Check present CPUs for determining _CPC is valid [ Upstream commit 2aeca6bd02776d7f56a49a32be0dd184f204d888 ] As this is a static check, it should be based upon what is currently present on the system. This makes probeing more deterministic. While local APIC flags field (lapic_flags) of cpu core in MADT table is 0, then the cpu core won't be enabled. In this case, _CPC won't be found in this core, and return back to _CPC invalid with walking through possible cpus (include disable cpus). This is not expected, so switch to check present CPUs instead. Reported-by: Jinzhou Su <Jinzhou.Su@xxxxxxx> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx> Signed-off-by: Huang Rui <ray.huang@xxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 3fbb17ecce2d5..6fe28a2d387bd 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -411,7 +411,7 @@ bool acpi_cpc_valid(void) struct cpc_desc *cpc_ptr; int cpu; - for_each_possible_cpu(cpu) { + for_each_present_cpu(cpu) { cpc_ptr = per_cpu(cpc_desc_ptr, cpu); if (!cpc_ptr) return false;