linux-kernel - [PATCH 5.15 599/846] ACPI: CPPC: Check present CPUs for determining

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Date:   Mon, 24 Jan 2022 19:41:56 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jinzhou Su <Jinzhou.Su@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Huang Rui <ray.huang@....com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 599/846] ACPI: CPPC: Check present CPUs for determining _CPC is valid

From: Mario Limonciello <mario.limonciello@....com>

[ 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@....com>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
Signed-off-by: Huang Rui <ray.huang@....com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.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 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;
-- 
2.34.1