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iommu/amd: Enhance "Completion-wait Time-out" error message

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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=1" 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 <dheerajkumar.srivastava@amd.com>
Reviewed-by: Ankit Soni <Ankit.Soni@amd.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Dheeraj Kumar Srivastava
2025-11-13 02:43:50 +05:30
committed by Joerg Roedel
parent a0c7005333
commit d1e281f832
2 changed files with 31 additions and 1 deletions
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4
drivers/iommu/amd/amd_iommu_types.h
View File

@@ -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 field [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 field [18:4] */
#define MMIO_CMD_BUFFER_TAIL(x) FIELD_GET(MMIO_CMD_TAIL_MASK, (x))
/* constants for event buffer handling */
#define EVT_BUFFER_SIZE 8192 /* 512 entries */

28
drivers/iommu/amd/iommu.c
View File

@@ -1157,6 +1157,25 @@ irqreturn_t amd_iommu_int_handler(int irq, void *data)
*
****************************************************************************/
static void dump_command_buffer(struct amd_iommu *iommu)
{
struct iommu_cmd *cmd;
u32 head, tail;
int i;
head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
tail = readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
pr_err("CMD Buffer head=%llu tail=%llu\n", MMIO_CMD_BUFFER_HEAD(head),
MMIO_CMD_BUFFER_TAIL(tail));
for (i = 0; i < CMD_BUFFER_ENTRIES; i++) {
cmd = (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 = 0;
@@ -1167,7 +1186,14 @@ static int wait_on_sem(struct amd_iommu *iommu, u64 data)
}
if (i == 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;
}