6.12-stable review patch. If anyone has any objections, please let me know.
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From: Gautham R. Shenoy gautham.shenoy@amd.com
[ Upstream commit 8821c8e80a65bc4eb73daf63b34aac6b8ad69461 ]
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)" superm1@kernel.org Signed-off-by: Gautham R. Shenoy gautham.shenoy@amd.com Link: https://patch.msgid.link/20251107074145.2340-4-gautham.shenoy@amd.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/cppc_acpi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 3ce5bb87d25b7..c4a1fee4b4873 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -463,7 +463,7 @@ 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) &&