linux-kernel - [PATCH] cpufreq: intel_pstate: Avoid using CPPC when ACPI CPC is not valid

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Message-Id: <20211118124553.599419-1-kai.heng.feng@canonical.com>
Date:   Thu, 18 Nov 2021 20:45:53 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     srinivas.pandruvada@...ux.intel.com, lenb@...nel.org,
        rafael@...nel.org, viresh.kumar@...aro.org
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        linux-pm@...r.kernel.org (open list:INTEL PSTATE DRIVER),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] cpufreq: intel_pstate: Avoid using CPPC when ACPI CPC is not valid

If ACPI CPC is not valid, dereference cpc_desc in cppc_get_perf() causes
a NULL pointer dereference. So avoid using CPPC for that scenario.

Fixes: 46573fd6369f ("cpufreq: intel_pstate: hybrid: Rework HWP calibration")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/cpufreq/intel_pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 815df3daae9df..24c7d705b99b6 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -3369,7 +3369,7 @@ static int __init intel_pstate_init(void)
 			if (!default_driver)
 				default_driver = &intel_pstate;
 
-			if (boot_cpu_has(X86_FEATURE_HYBRID_CPU))
+			if (boot_cpu_has(X86_FEATURE_HYBRID_CPU) && acpi_cpc_valid())
 				intel_pstate_cppc_set_cpu_scaling();
 
 			goto hwp_cpu_matched;
-- 
2.32.0