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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 BL6PEPF0001AB4C.mail.protection.outlook.com (10.167.242.70) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8093.14 via Frontend Transport; Wed, 23 Oct 2024 17:22:27 +0000 Received: from purico-9eb2host.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 15.1.2507.39; Wed, 23 Oct 2024 12:22:17 -0500 From: Yazen Ghannam To: CC: , , , , , , , , , , , , , , , , , , , Yazen Ghannam Subject: [PATCH 16/16] x86/amd_smn: Add support for debugfs access to SMN registers Date: Wed, 23 Oct 2024 17:21:50 +0000 Message-ID: <20241023172150.659002-17-yazen.ghannam@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241023172150.659002-1-yazen.ghannam@amd.com> References: <20241023172150.659002-1-yazen.ghannam@amd.com> Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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: BL6PEPF0001AB4C:EE_|BL1PR12MB5946:EE_ X-MS-Office365-Filtering-Correlation-Id: 9f102ef4-3a53-480e-3dcd-08dcf3874479 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|36860700013|1800799024|82310400026; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Oct 2024 17:22:27.3604 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9f102ef4-3a53-480e-3dcd-08dcf3874479 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: BL6PEPF0001AB4C.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5946 From: Mario Limonciello There are certain registers on AMD Zen systems that can only be accessed through SMN. Introduce a new interface that provides debugfs files for accessing SMN. As this introduces the capability for userspace to manipulate the hardware in unpredictable ways, taint the kernel when writing. Signed-off-by: Mario Limonciello Signed-off-by: Yazen Ghannam --- arch/x86/kernel/amd_smn.c | 83 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) diff --git a/arch/x86/kernel/amd_smn.c b/arch/x86/kernel/amd_smn.c index aeebd63234f9..618d9a05f3d7 100644 --- a/arch/x86/kernel/amd_smn.c +++ b/arch/x86/kernel/amd_smn.c @@ -7,6 +7,7 @@ #define pr_fmt(fmt) "amd_smn: " fmt #include +#include #include @@ -113,6 +114,82 @@ int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write } EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr); +static struct dentry *debugfs_dir; +static u16 debug_node; +static u32 debug_address; + +static ssize_t smn_node_write(struct file *file, const char __user *userbuf, + size_t count, loff_t *ppos) +{ + int ret; + + ret = kstrtou16_from_user(userbuf, count, 0, &debug_node); + if (ret) + return ret; + + return count; +} + +static int smn_node_show(struct seq_file *m, void *v) +{ + seq_printf(m, "0x%08x\n", debug_node); + return 0; +} + +static ssize_t smn_address_write(struct file *file, const char __user *userbuf, + size_t count, loff_t *ppos) +{ + int ret; + + ret = kstrtouint_from_user(userbuf, count, 0, &debug_address); + if (ret) + return ret; + + return count; +} + +static int smn_address_show(struct seq_file *m, void *v) +{ + seq_printf(m, "0x%08x\n", debug_address); + return 0; +} + +static int smn_value_show(struct seq_file *m, void *v) +{ + u32 val; + int ret; + + ret = amd_smn_read(debug_node, debug_address, &val); + if (ret) + return ret; + + seq_printf(m, "0x%08x\n", val); + return 0; +} + +static ssize_t smn_value_write(struct file *file, const char __user *userbuf, + size_t count, loff_t *ppos) +{ + u32 val; + int ret; + + ret = kstrtouint_from_user(userbuf, count, 0, &val); + if (ret) + return ret; + + add_taint(TAINT_USER, LOCKDEP_STILL_OK); + + ret = amd_smn_write(debug_node, debug_address, val); + if (ret) + return ret; + + return count; +} + +DEFINE_SHOW_STORE_ATTRIBUTE(smn_node); +DEFINE_SHOW_STORE_ATTRIBUTE(smn_address); +DEFINE_SHOW_STORE_ATTRIBUTE(smn_value); + static int amd_cache_roots(void) { u16 node, num_nodes = amd_num_nodes(); @@ -180,6 +257,12 @@ static int __init amd_smn_init(void) if (err) return err; + debugfs_dir = debugfs_create_dir("amd_smn", arch_debugfs_dir); + + debugfs_create_file("node", 0600, debugfs_dir, NULL, &smn_node_fops); + debugfs_create_file("address", 0600, debugfs_dir, NULL, &smn_address_fops); + debugfs_create_file("value", 0600, debugfs_dir, NULL, &smn_value_fops); + return 0; }