linux-kernel - [PATCH] ACPI: CPPC: Fix acpi_get_psd

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Message-ID: <20260211204838.21269-1-skelley@nvidia.com>
Date: Wed, 11 Feb 2026 20:48:38 +0000
From: Sean V Kelley <skelley@...dia.com>
To: rafael@...nel.org
Cc: lenb@...nel.org,
	pprakash@...eaurora.org,
	gautham.shenoy@....com,
	jamien@...dia.com,
	mochs@...dia.com,
	linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Sean V Kelley <skelley@...dia.com>
Subject: [PATCH] ACPI: CPPC: Fix acpi_get_psd_map() to iterate only 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 acpi_get_psd_map() iterates over all possible CPUs
when building the P-state domain map. When it encounters an offline CPU,
it returns -EFAULT, causing cppc_cpufreq initialization to fail.

This breaks systems booted with "nosmt" or "nosmt=force".

Fix by using for_each_online_cpu() so that only CPUs with valid CPC
descriptors are considered.

Fixes: 80b8286aeec0 ("ACPI / CPPC: support for batching CPPC requests")
Signed-off-by: Sean V Kelley <skelley@...dia.com>
---
 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 a09bdabaa804..e7cfd4cf029a 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -524,7 +524,7 @@ int acpi_get_psd_map(unsigned int cpu, struct cppc_cpudata *cpu_data)
 	else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
 		cpu_data->shared_type = CPUFREQ_SHARED_TYPE_ANY;

-	for_each_possible_cpu(i) {
+	for_each_online_cpu(i) {
 		if (i == cpu)
 			continue;

-- 
2.43.0