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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 SA2PEPF00001507.mail.protection.outlook.com (10.167.242.39) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9320.13 via Frontend Transport; Wed, 12 Nov 2025 21:14:10 +0000 Received: from BLRDHSRIVAS.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 15.2.2562.17; Wed, 12 Nov 2025 13:14:06 -0800 From: Dheeraj Kumar Srivastava To: , , , , CC: , , , Dheeraj Kumar Srivastava , Ankit Soni Subject: [PATCH v5] iommu/amd: Enhance "Completion-wait Time-out" error message Date: Thu, 13 Nov 2025 02:43:50 +0530 Message-ID: <20251112211350.894-1-dheerajkumar.srivastava@amd.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: SA2PEPF00001507:EE_|IA0PR12MB8327:EE_ X-MS-Office365-Filtering-Correlation-Id: 488d8f33-425a-4285-211c-08de22306c7e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|36860700013|376014|1800799024; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Nov 2025 21:14:10.6515 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 488d8f33-425a-4285-211c-08de22306c7e 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: SA2PEPF00001507.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB8327 Content-Type: text/plain; charset="utf-8" Current IOMMU driver prints "Completion-wait Time-out" error message with insufficient information to further debug the issue. Enhancing the error message as following: 1. Log IOMMU PCI device ID in the error message. 2. With "amd_iommu_dump=3D1" kernel command line option, dump entire command buffer entries including Head and Tail offset. Dump the entire command buffer only on the first 'Completion-wait Time-out' to avoid dmesg spam. Signed-off-by: Dheeraj Kumar Srivastava Reviewed-by: Ankit Soni Reviewed-by: Vasant Hegde --- Changes since v4: -> Changed head and tail variables from int to u32 in dump_command_buffer() to match readl() return type and updated pr_err() format specifiers from %d to %u accordingly for head and tail. (Ankit) Changes since v3: -> Dump the entire command buffer only on the first 'Completion-wait Time-o= ut' when amd_iommu_dump=3D1, instead of dumping it on every occurrence. drivers/iommu/amd/amd_iommu_types.h | 4 ++++ drivers/iommu/amd/iommu.c | 28 +++++++++++++++++++++++++++- 2 files changed, 31 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_io= mmu_types.h index 95f63c5f6159..c20798fc644d 100644 --- a/drivers/iommu/amd/amd_iommu_types.h +++ b/drivers/iommu/amd/amd_iommu_types.h @@ -247,6 +247,10 @@ #define CMD_BUFFER_ENTRIES 512 #define MMIO_CMD_SIZE_SHIFT 56 #define MMIO_CMD_SIZE_512 (0x9ULL << MMIO_CMD_SIZE_SHIFT) +#define MMIO_CMD_HEAD_MASK GENMASK_ULL(18, 4) /* Command buffer head ptr f= ield [18:4] */ +#define MMIO_CMD_BUFFER_HEAD(x) FIELD_GET(MMIO_CMD_HEAD_MASK, (x)) +#define MMIO_CMD_TAIL_MASK GENMASK_ULL(18, 4) /* Command buffer tail ptr f= ield [18:4] */ +#define MMIO_CMD_BUFFER_TAIL(x) FIELD_GET(MMIO_CMD_TAIL_MASK, (x)) =20 /* constants for event buffer handling */ #define EVT_BUFFER_SIZE 8192 /* 512 entries */ diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index eb348c63a8d0..c68b0fdc5433 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -1156,6 +1156,25 @@ irqreturn_t amd_iommu_int_handler(int irq, void *dat= a) * *************************************************************************= ***/ =20 +static void dump_command_buffer(struct amd_iommu *iommu) +{ + struct iommu_cmd *cmd; + u32 head, tail; + int i; + + head =3D readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET); + tail =3D readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET); + + pr_err("CMD Buffer head=3D%llu tail=3D%llu\n", MMIO_CMD_BUFFER_HEAD(head), + MMIO_CMD_BUFFER_TAIL(tail)); + + for (i =3D 0; i < CMD_BUFFER_ENTRIES; i++) { + cmd =3D (struct iommu_cmd *)(iommu->cmd_buf + i * sizeof(*cmd)); + pr_err("%3d: %08x %08x %08x %08x\n", i, cmd->data[0], cmd->data[1], cmd-= >data[2], + cmd->data[3]); + } +} + static int wait_on_sem(struct amd_iommu *iommu, u64 data) { int i =3D 0; @@ -1166,7 +1185,14 @@ static int wait_on_sem(struct amd_iommu *iommu, u64 = data) } =20 if (i =3D=3D LOOP_TIMEOUT) { - pr_alert("Completion-Wait loop timed out\n"); + + pr_alert("IOMMU %04x:%02x:%02x.%01x: Completion-Wait loop timed out\n", + iommu->pci_seg->id, PCI_BUS_NUM(iommu->devid), + PCI_SLOT(iommu->devid), PCI_FUNC(iommu->devid)); + + if (amd_iommu_dump) + DO_ONCE_LITE(dump_command_buffer, iommu); + return -EIO; } =20 --=20 2.25.1