linux-kernel - [PATCH v2 1/2] cpufreq/amd-pstate: Push adjust_perf vfunc init into cpu

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Message-ID: <20241028145542.1739160-1-superm1@kernel.org>
Date: Mon, 28 Oct 2024 09:55:41 -0500
From: Mario Limonciello <superm1@...nel.org>
To: "Gautham R . Shenoy" <gautham.shenoy@....com>,
	Perry Yuan <perry.yuan@....com>
Cc: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>,
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	linux-pm@...r.kernel.org (open list:CPU FREQUENCY SCALING FRAMEWORK),
	Mario Limonciello <mario.limonciello@....com>,
	Klara Modin <klarasmodin@...il.com>
Subject: [PATCH v2 1/2] cpufreq/amd-pstate: Push adjust_perf vfunc init into cpu_init

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

As the driver can be changed in and out of different modes it's possible
that adjust_perf is assigned when it shouldn't be.

This could happen if an MSR design is started up in passive mode and then
switches to active mode.

To solve this explicitly clear `adjust_perf` in amd_pstate_epp_cpu_init().

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
Cc: Klara Modin <klarasmodin@...il.com>
 drivers/cpufreq/amd-pstate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 206725219d8c9..e480da818d6f5 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1504,6 +1504,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 		WRITE_ONCE(cpudata->cppc_cap1_cached, value);
 	}
 
+	current_pstate_driver->adjust_perf = NULL;
+
 	return 0;
 
 free_cpudata1:
@@ -1866,8 +1868,6 @@ static int __init amd_pstate_init(void)
 	/* capability check */
 	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
 		pr_debug("AMD CPPC MSR based functionality is supported\n");
-		if (cppc_state != AMD_PSTATE_ACTIVE)
-			current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
 	} else {
 		pr_debug("AMD CPPC shared memory based functionality is supported\n");
 		static_call_update(amd_pstate_cppc_enable, shmem_cppc_enable);
-- 
2.43.0