Documentation/ABI/testing/debugfs-intel-iommu
What: /sys/kernel/debug/iommu/intel/iommu_regset
Date: December 2023
Contact: Jingqi Liu <Jingqi.liu@intel.com>
Description:
This file dumps all the register contents for each IOMMU device.
Example in Kabylake:
::
$ sudo cat /sys/kernel/debug/iommu/intel/iommu_regset
IOMMU: dmar0 Register Base Address: 26be37000
Name Offset Contents
VER 0x00 0x0000000000000010
GCMD 0x18 0x0000000000000000
GSTS 0x1c 0x00000000c7000000
FSTS 0x34 0x0000000000000000
FECTL 0x38 0x0000000000000000
[...]
IOMMU: dmar1 Register Base Address: fed90000
Name Offset Contents
VER 0x00 0x0000000000000010
GCMD 0x18 0x0000000000000000
GSTS 0x1c 0x00000000c7000000
FSTS 0x34 0x0000000000000000
FECTL 0x38 0x0000000000000000
[...]
IOMMU: dmar2 Register Base Address: fed91000
Name Offset Contents
VER 0x00 0x0000000000000010
GCMD 0x18 0x0000000000000000
GSTS 0x1c 0x00000000c7000000
FSTS 0x34 0x0000000000000000
FECTL 0x38 0x0000000000000000
[...]
What: /sys/kernel/debug/iommu/intel/ir_translation_struct
Date: December 2023
Contact: Jingqi Liu <Jingqi.liu@intel.com>
Description:
This file dumps the table entries for Interrupt
remapping and Interrupt posting.
Example in Kabylake:
::
$ sudo cat /sys/kernel/debug/iommu/intel/ir_translation_struct
Remapped Interrupt supported on IOMMU: dmar0
IR table address:100900000
Entry SrcID DstID Vct IRTE_high IRTE_low
0 00:0a.0 00000080 24 0000000000040050 000000800024000d
1 00:0a.0 00000001 ef 0000000000040050 0000000100ef000d
Remapped Interrupt supported on IOMMU: dmar1
IR table address:100300000
Entry SrcID DstID Vct IRTE_high IRTE_low
0 00:02.0 00000002 26 0000000000040010 000000020026000d
[...]
****
Posted Interrupt supported on IOMMU: dmar0
IR table address:100900000
Entry SrcID PDA_high PDA_low Vct IRTE_high IRTE_low
What: /sys/kernel/debug/iommu/intel/dmar_translation_struct
Date: December 2023
Contact: Jingqi Liu <Jingqi.liu@intel.com>
Description:
This file dumps Intel IOMMU DMA remapping tables, such
as root table, context table, PASID directory and PASID
table entries in debugfs. For legacy mode, it doesn't
support PASID, and hence PASID field is defaulted to
'-1' and other PASID related fields are invalid.
Example in Kabylake:
::
$ sudo cat /sys/kernel/debug/iommu/intel/dmar_translation_struct
IOMMU dmar1: Root Table Address: 0x103027000
B.D.F Root_entry
00:02.0 0x0000000000000000:0x000000010303e001
Context_entry
0x0000000000000102:0x000000010303f005
PASID PASID_table_entry
-1 0x0000000000000000:0x0000000000000000:0x0000000000000000
IOMMU dmar0: Root Table Address: 0x103028000
B.D.F Root_entry
00:0a.0 0x0000000000000000:0x00000001038a7001
Context_entry
0x0000000000000000:0x0000000103220e7d
PASID PASID_table_entry
0 0x0000000000000000:0x0000000000800002:0x00000001038a5089
[...]
What: /sys/kernel/debug/iommu/intel/invalidation_queue
Date: December 2023
Contact: Jingqi Liu <Jingqi.liu@intel.com>
Description:
This file exports invalidation queue internals of each
IOMMU device.
Example in Kabylake:
::
$ sudo cat /sys/kernel/debug/iommu/intel/invalidation_queue
Invalidation queue on IOMMU: dmar0
Base: 0x10022e000 Head: 20 Tail: 20
Index qw0 qw1 qw2
0 0000000000000014 0000000000000000 0000000000000000
1 0000000200000025 0000000100059c04 0000000000000000
2 0000000000000014 0000000000000000 0000000000000000
qw3 status
0000000000000000 0000000000000000
0000000000000000 0000000000000000
0000000000000000 0000000000000000
[...]
Invalidation queue on IOMMU: dmar1
Base: 0x10026e000 Head: 32 Tail: 32
Index qw0 qw1 status
0 0000000000000004 0000000000000000 0000000000000000
1 0000000200000025 0000000100059804 0000000000000000
2 0000000000000011 0000000000000000 0000000000000000
[...]
What: /sys/kernel/debug/iommu/intel/dmar_perf_latency
Date: December 2023
Contact: Jingqi Liu <Jingqi.liu@intel.com>
Description:
This file is used to control and show counts of
execution time ranges for various types per DMAR.
Firstly, write a value to
/sys/kernel/debug/iommu/intel/dmar_perf_latency
to enable sampling.
The possible values are as follows:
* 0 - disable sampling all latency data
* 1 - enable sampling IOTLB invalidation latency data
* 2 - enable sampling devTLB invalidation latency data
* 3 - enable sampling intr entry cache invalidation latency data
Next, read /sys/kernel/debug/iommu/intel/dmar_perf_latency gives
a snapshot of sampling result of all enabled monitors.
Examples in Kabylake:
::
1) Disable sampling all latency data:
$ sudo echo 0 > /sys/kernel/debug/iommu/intel/dmar_perf_latency
2) Enable sampling IOTLB invalidation latency data
$ sudo echo 1 > /sys/kernel/debug/iommu/intel/dmar_perf_latency
$ sudo cat /sys/kernel/debug/iommu/intel/dmar_perf_latency
IOMMU: dmar0 Register Base Address: 26be37000
<0.1us 0.1us-1us 1us-10us 10us-100us 100us-1ms
inv_iotlb 0 0 0 0 0
1ms-10ms >=10ms min(us) max(us) average(us)
inv_iotlb 0 0 0 0 0
[...]
IOMMU: dmar2 Register Base Address: fed91000
<0.1us 0.1us-1us 1us-10us 10us-100us 100us-1ms
inv_iotlb 0 0 18 0 0
1ms-10ms >=10ms min(us) max(us) average(us)
inv_iotlb 0 0 2 2 2
3) Enable sampling devTLB invalidation latency data
$ sudo echo 2 > /sys/kernel/debug/iommu/intel/dmar_perf_latency
$ sudo cat /sys/kernel/debug/iommu/intel/dmar_perf_latency
IOMMU: dmar0 Register Base Address: 26be37000
<0.1us 0.1us-1us 1us-10us 10us-100us 100us-1ms
inv_devtlb 0 0 0 0 0
>=10ms min(us) max(us) average(us)
inv_devtlb 0 0 0 0
[...]
What: /sys/kernel/debug/iommu/intel/<bdf>/domain_translation_struct
Date: December 2023
Contact: Jingqi Liu <Jingqi.liu@intel.com>
Description:
This file dumps a specified page table of Intel IOMMU
in legacy mode or scalable mode.
For a device that only supports legacy mode, dump its
page table by the debugfs file in the debugfs device
directory. e.g.
/sys/kernel/debug/iommu/intel/0000:00:02.0/domain_translation_struct.
For a device that supports scalable mode, dump the
page table of specified pasid by the debugfs file in
the debugfs pasid directory. e.g.
/sys/kernel/debug/iommu/intel/0000:00:02.0/1/domain_translation_struct.
Examples in Kabylake:
::
1) Dump the page table of device "0000:00:02.0" that only supports legacy mode.
$ sudo cat /sys/kernel/debug/iommu/intel/0000:00:02.0/domain_translation_struct
Device 0000:00:02.0 @0x1017f8000
IOVA_PFN PML5E PML4E
0x000000008d800 | 0x0000000000000000 0x00000001017f9003
0x000000008d801 | 0x0000000000000000 0x00000001017f9003
0x000000008d802 | 0x0000000000000000 0x00000001017f9003
PDPE PDE PTE
0x00000001017fa003 0x00000001017fb003 0x000000008d800003
0x00000001017fa003 0x00000001017fb003 0x000000008d801003
0x00000001017fa003 0x00000001017fb003 0x000000008d802003
[...]
2) Dump the page table of device "0000:00:0a.0" with PASID "1" that
supports scalable mode.
$ sudo cat /sys/kernel/debug/iommu/intel/0000:00:0a.0/1/domain_translation_struct
Device 0000:00:0a.0 with pasid 1 @0x10c112000
IOVA_PFN PML5E PML4E
0x0000000000000 | 0x0000000000000000 0x000000010df93003
0x0000000000001 | 0x0000000000000000 0x000000010df93003
0x0000000000002 | 0x0000000000000000 0x000000010df93003
PDPE PDE PTE
0x0000000106ae6003 0x0000000104b38003 0x0000000147c00803
0x0000000106ae6003 0x0000000104b38003 0x0000000147c01803
0x0000000106ae6003 0x0000000104b38003 0x0000000147c02803
[...]