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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 BN1PEPF0000468D.mail.protection.outlook.com (10.167.243.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.181.6 via Frontend Transport; Mon, 29 Jun 2026 07:39:45 +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; Mon, 29 Jun 2026 02:39:43 -0500 From: Muralidhara M K To: CC: , , Muralidhara M K Subject: [PATCH 4/4] platform/x86/amd/hsmp: Gate the data plane on a fully initialized socket Date: Mon, 29 Jun 2026 13:09:23 +0530 Message-ID: <20260629073923.1595696-5-muralidhara.mk@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260629073923.1595696-1-muralidhara.mk@amd.com> References: <20260629073923.1595696-1-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: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN1PEPF0000468D:EE_|MW6PR12MB8867:EE_ X-MS-Office365-Filtering-Correlation-Id: 9c37dc05-51e4-4ca8-fbb2-08ded5b19700 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|23010399003|376014|1800799024|82310400026|13003099007|6133799003|56012099006|11063799006|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 571t2NeF6sH86F7o5pONUd6FzAqqOGNvU8YZnBBIAmyOO6DSrSYgQzUlJwyzOJ1sBc1H80KkkDWxm+prpKJOn9SC9LKJp1l4GZajyqMGi/EQkhDrR5v9lLxXN1G1rTavrqCOBgEmnQc4BJm9EunFu57Ea+w6+HBJp3MGWWPxXJc5auQBoBOEU2PVIyxZE/2/GgGfUrzCBxpsinUEzHdYgh+Wv46Cnmsnex2bhOXj3mfztU6DTsbdqI2uSkkyI/OVQecv9w20fTc0xq6JNzPKIEjjGTMco6kdvhNBHeb6UpAhy6YDvNCxWsqo7S2cce+rOHFJ0G03BKApeh7kAbXnew1AymlMkICxANeWDTP6BQ7GmomYTqxWqgfeKr2SU0GxDsXK8q+5m65we0fvtZqd5DkQQoCsP4d343QWQXfA7BZpVNhDxFoXHK9z6NrLGaBN X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jun 2026 07:39:45.2146 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9c37dc05-51e4-4ca8-fbb2-08ded5b19700 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: BN1PEPF0000468D.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW6PR12MB8867 hsmp_parse_acpi_table() published sock->dev before hsmp_read_acpi_crs() had mapped virt_base_addr. sock->dev is the readiness gate for the lock-free data plane, so on a multi-socket system - where socket 0 exposes /dev/hsmp before later sockets finish probing - an ioctl aimed at a socket still in bring-up could pass the gate and dereference a NULL virt_base_addr. Publish sock->dev last with smp_store_release() once virt_base_addr, the mailbox offsets and the semaphore are initialized, and read it with smp_load_acquire() in hsmp_send_message() so a non-NULL dev guarantees the rest of the socket state is visible. Signed-off-by: Muralidhara M K Link: https://lore.kernel.org/platform-driver-x86/20260625123337.886435-5-muralidhara.mk@amd.com/T/#u [1] --- drivers/platform/x86/amd/hsmp/acpi.c | 18 ++++++++++++++++-- drivers/platform/x86/amd/hsmp/hsmp.c | 12 ++++++++++++ 2 files changed, 28 insertions(+), 2 deletions(-) diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c index f7fbba4c6b66..5aec3bded712 100644 --- a/drivers/platform/x86/amd/hsmp/acpi.c +++ b/drivers/platform/x86/amd/hsmp/acpi.c @@ -224,7 +224,6 @@ static int hsmp_parse_acpi_table(struct device *dev, u16 sock_ind) int ret; sock->sock_ind = sock_ind; - sock->dev = dev; sock->amd_hsmp_rdwr = amd_hsmp_acpi_rdwr; sema_init(&sock->hsmp_sem, 1); @@ -237,7 +236,22 @@ static int hsmp_parse_acpi_table(struct device *dev, u16 sock_ind) return ret; /* Read mailbox offsets from DSD table */ - return hsmp_read_acpi_dsd(sock, dev); + ret = hsmp_read_acpi_dsd(sock, dev); + if (ret) + return ret; + + /* + * Publish sock->dev last. hsmp_send_message() uses it (via + * smp_load_acquire()) as the readiness gate for the lock-free data + * plane, so it must become visible only after virt_base_addr, the + * mailbox offsets and the semaphore are fully initialized. On a + * multi-socket system socket 0 exposes /dev/hsmp before later sockets + * finish probing, so without this an ioctl aimed at a socket still in + * bring-up could pass the gate and dereference a NULL virt_base_addr. + */ + smp_store_release(&sock->dev, dev); + + return 0; } static ssize_t hsmp_metric_tbl_acpi_read(struct file *filp, struct kobject *kobj, diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c index 6a26937fc2b5..0cd4f691db49 100644 --- a/drivers/platform/x86/amd/hsmp/hsmp.c +++ b/drivers/platform/x86/amd/hsmp/hsmp.c @@ -223,6 +223,18 @@ int hsmp_send_message(struct hsmp_message *msg) sock_ind = array_index_nospec(msg->sock_ind, hsmp_pdev.num_sockets); sock = &hsmp_pdev.sock[sock_ind]; + /* + * A slot exists for every possible socket, but it is only usable once + * that socket has actually been probed. Reject messages aimed at a + * socket that was never brought up or is still in bring-up, so we never + * operate on a zero-initialized semaphore or an unmapped mailbox. A + * non-NULL dev also guarantees virt_base_addr, the mailbox offsets and + * the semaphore are visible. + */ + /* Pairs with smp_store_release(&sock->dev) in hsmp_parse_acpi_table(). */ + if (!smp_load_acquire(&sock->dev)) + return -ENODEV; + ret = down_interruptible(&sock->hsmp_sem); if (ret < 0) return ret; -- 2.43.0