linux-kernel - [PATCH v2] ACPI: CPPC: Fix remaining for_each_possible

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Message-ID: <20260211212254.30190-1-skelley@nvidia.com>
Date: Wed, 11 Feb 2026 21:22:54 +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 v2] ACPI: CPPC: Fix remaining for_each_possible_cpu() to use 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 send_pcc_cmd() and acpi_get_psd_map() still iterate over all
possible CPUs. In acpi_get_psd_map(), encountering an offline CPU
returns -EFAULT, causing cppc_cpufreq initialization to fail.

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

Fix by using for_each_online_cpu() in both functions.

Fixes: 80b8286aeec0 ("ACPI / CPPC: support for batching CPPC requests")
Signed-off-by: Sean V Kelley <skelley@...dia.com>
---

Notes:
    v2: Also fix for_each_possible_cpu() in send_pcc_cmd() (Rafael)

 drivers/acpi/cppc_acpi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index a09bdabaa804..0e6ffb188fe7 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -362,7 +362,7 @@ static int send_pcc_cmd(int pcc_ss_id, u16 cmd)
 end:
 	if (cmd == CMD_WRITE) {
 		if (unlikely(ret)) {
-			for_each_possible_cpu(i) {
+			for_each_online_cpu(i) {
 				struct cpc_desc *desc = per_cpu(cpc_desc_ptr, i);
 
 				if (!desc)
@@ -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