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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CO1PEPF00012E83.mail.protection.outlook.com (10.167.249.58) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.223.9 via Frontend Transport; Mon, 13 Jul 2026 04:40:29 +0000 Received: from dcsm-trdripper1.amd.com (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.41; Sun, 12 Jul 2026 23:40:27 -0500 From: Muralidhara M K To: CC: , , , Muralidhara M K Subject: [PATCH v6 3/6] platform/x86/amd/hsmp: Serialize per-socket metric table reads with a mutex Date: Mon, 13 Jul 2026 10:10:02 +0530 Message-ID: <20260713044005.1194115-4-muralidhara.mk@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260713044005.1194115-1-muralidhara.mk@amd.com> References: <20260713044005.1194115-1-muralidhara.mk@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PEPF00012E83:EE_|SA1PR12MB8841:EE_ X-MS-Office365-Filtering-Correlation-Id: 4e798de1-555f-460a-0c94-08dee098ddaa X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700016|376014|82310400026|23010399003|18002099003|22082099003|11063799006|56012099006|6133799003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: uo6oC0QEa+cpIm56f7Q9aj9wsCkprDYhCmiAtgo4w1p5+af8r6aTeBfW9kGd8x0rOiZA3lsfDw/N+VhgpeIbeDvcxTeiJeaPVWKX9SYXQbW07Y0bPqrAw6nosuSLBP7yiLwFPQIOElFsWKwzh6j//BMDZ/dZDCNVNVxFo/0yRWqLNaIBtZTGotwIfvubIPw1p+lEAnrOAknNK7DXNMZUAaA6O5UyXHsZ+OG22wfyOAhMCvleWfHU2kLzsZLl2OEjR1WcXydJlZmwhVp3JbQ4CrmALco7WxgXv9gQjMc1nXQZAQ1j+AKUBGR3GjRyFaDLLMZilqKxStBgcjYFG1pquewP5hg/lt59topEb7GEy6KDR9Dv7DmqJEzPEVzWRht17+Ov3roLGBssvRTDB97K4FaUnPK0hr5IpNLRz9eJdNo18Wkh9XURv3S6mPlEyMlN X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Jul 2026 04:40:29.0653 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 4e798de1-555f-460a-0c94-08dee098ddaa 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF00012E83.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB8841 HSMP_GET_METRIC_TABLE makes the firmware refill a shared per-socket metric DRAM region, which hsmp_metric_tbl_read() then copies out with memcpy_fromio(). Two concurrent readers of the metrics_bin sysfs attribute on the same socket can race: one can trigger a fresh fill while the other is mid-copy and return a torn snapshot. (The hwmon path does not touch this region; it only issues power messages via hsmp_send_message().) Embed a struct mutex metric_read_lock in each hsmp_socket and hold it across the fill-and-copy in hsmp_metric_tbl_read(). Add hsmp_init_metric_read_locks() and hsmp_destroy_metric_read_locks(), which take only struct hsmp_plat_device and iterate pdev->sock[] over pdev->num_sockets so the caller cannot pass a count that disagrees with the array. Wire them into both front-ends' probe and teardown paths so the mutex is always initialized before metrics_bin is exposed: the platform driver and the ACPI driver both drive hsmp_metric_tbl_read() through the same 0444 metrics_bin attribute. Doing this in one patch avoids a bisection point where an ACPI read would lock an uninitialized mutex. Signed-off-by: Muralidhara M K --- drivers/platform/x86/amd/hsmp/acpi.c | 3 +++ drivers/platform/x86/amd/hsmp/hsmp.c | 28 ++++++++++++++++++++++++++++ drivers/platform/x86/amd/hsmp/hsmp.h | 5 +++++ drivers/platform/x86/amd/hsmp/plat.c | 3 +++ 4 files changed, 39 insertions(+) diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c index a23797bd1dd5..a092d7589bcb 100644 --- a/drivers/platform/x86/amd/hsmp/acpi.c +++ b/drivers/platform/x86/amd/hsmp/acpi.c @@ -639,6 +639,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev) GFP_KERNEL); if (!hsmp_pdev->sock) return -ENOMEM; + + hsmp_init_metric_read_locks(hsmp_pdev); } ret = init_acpi(&pdev->dev); @@ -670,6 +672,7 @@ static void hsmp_acpi_remove(struct platform_device *pdev) */ if (hsmp_pdev->is_probed) { hsmp_misc_deregister(); + hsmp_destroy_metric_read_locks(hsmp_pdev); hsmp_pdev->is_probed = false; } } diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c index 008f3c0b2ad7..fd36c8f142c0 100644 --- a/drivers/platform/x86/amd/hsmp/hsmp.c +++ b/drivers/platform/x86/amd/hsmp/hsmp.c @@ -10,9 +10,11 @@ #include #include +#include #include #include #include +#include #include #include #include @@ -415,6 +417,14 @@ ssize_t hsmp_metric_tbl_read(struct hsmp_socket *sock, char *buf, size_t size) msg.msg_id = HSMP_GET_METRIC_TABLE; msg.sock_ind = sock->sock_ind; + /* + * HSMP_GET_METRIC_TABLE makes firmware refill this socket's shared + * metric DRAM region, which is then copied out below. Hold the + * per-socket lock across the fill-and-copy so concurrent readers of the + * same socket cannot return a torn snapshot. + */ + guard(mutex)(&sock->metric_read_lock); + ret = hsmp_send_message(&msg); if (ret) return ret; @@ -424,6 +434,24 @@ ssize_t hsmp_metric_tbl_read(struct hsmp_socket *sock, char *buf, size_t size) } EXPORT_SYMBOL_NS_GPL(hsmp_metric_tbl_read, "AMD_HSMP"); +void hsmp_init_metric_read_locks(struct hsmp_plat_device *pdev) +{ + u16 i; + + for (i = 0; i < pdev->num_sockets; i++) + mutex_init(&pdev->sock[i].metric_read_lock); +} +EXPORT_SYMBOL_NS_GPL(hsmp_init_metric_read_locks, "AMD_HSMP"); + +void hsmp_destroy_metric_read_locks(struct hsmp_plat_device *pdev) +{ + u16 i; + + for (i = 0; i < pdev->num_sockets; i++) + mutex_destroy(&pdev->sock[i].metric_read_lock); +} +EXPORT_SYMBOL_NS_GPL(hsmp_destroy_metric_read_locks, "AMD_HSMP"); + void hsmp_unmap_metric_tbls(struct hsmp_plat_device *pdev) { struct hsmp_socket *sock; diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h index b0d67b93363d..ec92c2a429bb 100644 --- a/drivers/platform/x86/amd/hsmp/hsmp.h +++ b/drivers/platform/x86/amd/hsmp/hsmp.h @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -44,6 +45,8 @@ struct hsmp_socket { void __iomem *metric_tbl_addr; void __iomem *virt_base_addr; struct semaphore hsmp_sem; + /* Serializes HSMP_GET_METRIC_TABLE fill-and-copy for this socket */ + struct mutex metric_read_lock; char name[HSMP_ATTR_GRP_NAME_SIZE]; struct device *dev; u16 sock_ind; @@ -65,6 +68,8 @@ void hsmp_misc_deregister(void); int hsmp_misc_register(struct device *dev); int hsmp_get_tbl_dram_base(u16 sock_ind); void hsmp_unmap_metric_tbls(struct hsmp_plat_device *pdev); +void hsmp_init_metric_read_locks(struct hsmp_plat_device *pdev); +void hsmp_destroy_metric_read_locks(struct hsmp_plat_device *pdev); ssize_t hsmp_metric_tbl_read(struct hsmp_socket *sock, char *buf, size_t size); struct hsmp_plat_device *get_hsmp_pdev(void); #if IS_ENABLED(CONFIG_HWMON) diff --git a/drivers/platform/x86/amd/hsmp/plat.c b/drivers/platform/x86/amd/hsmp/plat.c index b5f2120765c8..7a16d1ab463b 100644 --- a/drivers/platform/x86/amd/hsmp/plat.c +++ b/drivers/platform/x86/amd/hsmp/plat.c @@ -212,6 +212,7 @@ static int init_platform_device(struct device *dev) static void hsmp_pltdrv_release(void *data) { hsmp_unmap_metric_tbls(hsmp_pdev); + hsmp_destroy_metric_read_locks(hsmp_pdev); } static int hsmp_pltdrv_probe(struct platform_device *pdev) @@ -224,6 +225,8 @@ static int hsmp_pltdrv_probe(struct platform_device *pdev) if (!hsmp_pdev->sock) return -ENOMEM; + hsmp_init_metric_read_locks(hsmp_pdev); + ret = devm_add_action_or_reset(&pdev->dev, hsmp_pltdrv_release, NULL); if (ret) return ret; -- 2.34.1