diff options
| author | Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> | 2025-07-02 15:08:04 +0530 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2025-07-15 11:41:53 +0100 |
| commit | 39215bb3b0d929f336b6c82ff1665a3377ca0d4f (patch) | |
| tree | c8367619f673034fee90ae4727e7cbd838554ea5 | |
| parent | 349ad6d5263a6299aae64ad59d82bb5b03b478fa (diff) | |
iommu/amd: Add documentation for AMD IOMMU debugfs support
Add documentation describing how to use AMD IOMMU debugfs support to
dump IOMMU data structures - IRT table, Device table, Registers (MMIO and
Capability) and command buffer.
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20250702093804.849-9-dheerajkumar.srivastava@amd.com
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | Documentation/ABI/testing/debugfs-amd-iommu | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/debugfs-amd-iommu b/Documentation/ABI/testing/debugfs-amd-iommu new file mode 100644 index 000000000000..c14b1620aec1 --- /dev/null +++ b/Documentation/ABI/testing/debugfs-amd-iommu @@ -0,0 +1,114 @@ +What: /sys/kernel/debug/iommu/amd/iommu<x>/mmio +Date: January 2025 +Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> +Description: + This file provides read/write access for user input. Users specify the + MMIO register offset for iommu<x>, and the file outputs the corresponding + MMIO register value of iommu<x> + + Example: + $ echo "0x18" > /sys/kernel/debug/iommu/amd/iommu00/mmio + $ cat /sys/kernel/debug/iommu/amd/iommu00/mmio + + Output: + Offset:0x18 Value:0x000c22000003f48d + +What: /sys/kernel/debug/iommu/amd/iommu<x>/capability +Date: January 2025 +Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> +Description: + This file provides read/write access for user input. Users specify the + capability register offset for iommu<x>, and the file outputs the + corresponding capability register value of iommu<x>. + + Example: + $ echo "0x10" > /sys/kernel/debug/iommu/amd/iommu00/capability + $ cat /sys/kernel/debug/iommu/amd/iommu00/capability + + Output: + Offset:0x10 Value:0x00203040 + +What: /sys/kernel/debug/iommu/amd/iommu<x>/cmdbuf +Date: January 2025 +Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> +Description: + This file is a read-only output file containing iommu<x> command + buffer entries. + + Examples: + $ cat /sys/kernel/debug/iommu/amd/iommu<x>/cmdbuf + + Output: + CMD Buffer Head Offset:339 Tail Offset:339 + 0: 00835001 10000001 00003c00 00000000 + 1: 00000000 30000005 fffff003 7fffffff + 2: 00835001 10000001 00003c01 00000000 + 3: 00000000 30000005 fffff003 7fffffff + 4: 00835001 10000001 00003c02 00000000 + 5: 00000000 30000005 fffff003 7fffffff + 6: 00835001 10000001 00003c03 00000000 + 7: 00000000 30000005 fffff003 7fffffff + 8: 00835001 10000001 00003c04 00000000 + 9: 00000000 30000005 fffff003 7fffffff + 10: 00835001 10000001 00003c05 00000000 + 11: 00000000 30000005 fffff003 7fffffff + [...] + +What: /sys/kernel/debug/iommu/amd/devid +Date: January 2025 +Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> +Description: + This file provides read/write access for user input. Users specify the + device ID, which can be used to dump IOMMU data structures such as the + interrupt remapping table and device table. + + Example: + 1. + $ echo 0000:01:00.0 > /sys/kernel/debug/iommu/amd/devid + $ cat /sys/kernel/debug/iommu/amd/devid + + Output: + 0000:01:00.0 + + 2. + $ echo 01:00.0 > /sys/kernel/debug/iommu/amd/devid + $ cat /sys/kernel/debug/iommu/amd/devid + + Output: + 0000:01:00.0 + +What: /sys/kernel/debug/iommu/amd/devtbl +Date: January 2025 +Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> +Description: + This file is a read-only output file containing the device table entry + for the device ID provided in /sys/kernel/debug/iommu/amd/devid. + + Example: + $ cat /sys/kernel/debug/iommu/amd/devtbl + + Output: + DeviceId QWORD[3] QWORD[2] QWORD[1] QWORD[0] iommu + 0000:01:00.0 0000000000000000 20000001373b8013 0000000000000038 6000000114d7b603 iommu3 + +What: /sys/kernel/debug/iommu/amd/irqtbl +Date: January 2025 +Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> +Description: + This file is a read-only output file containing valid IRT table entries + for the device ID provided in /sys/kernel/debug/iommu/amd/devid. + + Example: + $ cat /sys/kernel/debug/iommu/amd/irqtbl + + Output: + DeviceId 0000:01:00.0 + IRT[0000] 0000000000000020 0000000000000241 + IRT[0001] 0000000000000020 0000000000000841 + IRT[0002] 0000000000000020 0000000000002041 + IRT[0003] 0000000000000020 0000000000008041 + IRT[0004] 0000000000000020 0000000000020041 + IRT[0005] 0000000000000020 0000000000080041 + IRT[0006] 0000000000000020 0000000000200041 + IRT[0007] 0000000000000020 0000000000800041 + [...] |