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Mon, 15 May 2023 11:34:21 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DM6NAM11FT065.mail.protection.outlook.com (10.13.172.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.6411.14 via Frontend Transport; Mon, 15 May 2023 11:34:21 +0000 Received: from beas.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Mon, 15 May 2023 06:34:18 -0500 From: Wyes Karny To: , , CC: , , , Wyes Karny Subject: [PATCH v3 0/2] cpufreq/amd-pstate: Fix null pointer dereference when frequency invariance is disabled Date: Mon, 15 May 2023 11:34:02 +0000 Message-ID: <20230515113404.4259-1-wyes.karny@amd.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6NAM11FT065:EE_|DS0PR12MB8020:EE_ X-MS-Office365-Filtering-Correlation-Id: dfed1197-ce55-41f8-17ad-08db553853ec X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 May 2023 11:34:21.6786 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: dfed1197-ce55-41f8-17ad-08db553853ec X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT065.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8020 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Currently, amd_pstate only uses `adjust_perf` and `target` callback functions to get the frequency/effective utilization data from scaling governors. But the governor can switch back to fast_switch callback when frequency invariance is disabled. In that case, if the driver didn't set fast_switch function pointer, null pointer dereference can happen and kernel will crash. Currently, frequency invariance is turned off when any anomaly is detected with aperf/mperf readings. Which triggers this problem. Fix this by adding `fast_switch` function in the amd_pstate driver. The same problem could arise with intel_pstate driver when the driver is in passive mode and the governor is schedutil. Additionally, display a warning message if the scaling driver sets fast_swich_possible flag but not fast_switch function pointer. Changelog: v2 -> v3 - Add fast_switch callback in amd_pstate and warn if any driver sets fast_swich_possible flag but not fast_switch function pointer. v1 -> v2 - Remove fast_switch_enabled flag dependency for adjust_perf callback v1: https://lore.kernel.org/linux-pm/20230410095045.14872-1-wyes.karny@amd.com/ v2: https://lore.kernel.org/linux-pm/20230509180503.739208-1-wyes.karny@amd.com/ Gautham R. Shenoy (1): amd_pstate: Add ->fast_switch() callback Wyes Karny (1): cpufreq: Warn if fast_switch is not set drivers/cpufreq/amd-pstate.c | 35 +++++++++++++++++++++++++++++------ drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++++ include/linux/cpufreq.h | 5 ++++- 3 files changed, 51 insertions(+), 7 deletions(-)