From: Gautham R. Shenoy Date: Fri, 7 Nov 2025 07:41:43 +0000 (+0530) Subject: ACPI: CPPC: Perform fast check switch only for online CPUs X-Git-Tag: v6.18-rc6~28^2^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8821c8e80a65bc4eb73daf63b34aac6b8ad69461;p=thirdparty%2Fkernel%2Flinux.git ACPI: CPPC: Perform fast check switch only for online CPUs per_cpu(cpc_desc_ptr, cpu) object is initialized for only the online CPUs via acpi_soft_cpu_online() --> __acpi_processor_start() --> acpi_cppc_processor_probe(). However the function cppc_allow_fast_switch() checks for the validity of the _CPC object for all the present CPUs. This breaks when the kernel is booted with "nosmt=force". Check fast_switch capability only on online CPUs Fixes: 15eece6c5b05 ("ACPI: CPPC: Fix NULL pointer dereference when nosmp is used") Reviewed-by: "Mario Limonciello (AMD) (kernel.org)" Signed-off-by: Gautham R. Shenoy Link: https://patch.msgid.link/20251107074145.2340-4-gautham.shenoy@amd.com Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index da6b35ac8c87..7492c9922866 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -476,7 +476,7 @@ bool cppc_allow_fast_switch(void) struct cpc_desc *cpc_ptr; int cpu; - for_each_present_cpu(cpu) { + for_each_online_cpu(cpu) { cpc_ptr = per_cpu(cpc_desc_ptr, cpu); desired_reg = &cpc_ptr->cpc_regs[DESIRED_PERF]; if (!CPC_IN_SYSTEM_MEMORY(desired_reg) &&