Subject: Re: [RFC PATCH v2 0/5] Add debugfs support for ARM SMMUv3

From: Qinxin Xia <[email-masked]>
Date: Sat, 28 Mar 2026 18:14:33 +0800

Sorry！patch 2 cannot convert from y to UTF-8,I will release a new
version soon; please ignore this one.

On 2026/3/28 18:09:48, Qinxin Xia <[email-masked]> wrote:
> Add a comprehensive debugfs framework to the ARM SMMUv3 driver,
> providing visibility into internal hardware state for debugging
> and performance analysis. The debugfs entries are organized under
> /sys/kernel/debug/iommu/arm_smmu_v3/, with per-SMMU instance directories
> and per-device stream table entries.
>                   
> Each SMMU instance provides:
> - capabilities – static SMMU features and queue sizes.
> - registers – SMMU key registers.
> - stream_table/ – a directory per device with subdirectories per Stream ID.
>                   
> Each Stream ID subdirectory contains:
> - ste – the Stream Table Entry in decoded and raw format.
> - cd – all valid Context Descriptors (Stage 1 translation tables) associated with the device.
> - a symlink named with the device’s BDF/name pointing to its sysfs directory for easy navigation.
>                   
> /sys/kernel/debug/iommu/arm_smmu_v3/smmu0/stream_table/
> └── <sid>/
>      ├─── ste
>      ├─── cd
>      └─── <dev_name>
> 
> Changes since V1:
>    Address the comments from Nicolin:
>    1.Fixed the incorrect comments and replaced 'kzalloc' with 'kzalloc_obj'
>    2.'stream_table_create/stream_table_remove' is called in probe_device/release_device
>    3.Reused some functions in the driver
> 
>    Address the comments from Robin:
>    1.Remove unnecessary CR0*EN extra strings
>    2.Remove the limit on ssid
> 
>    Address the comments from Robin and Nicolin:
>    1.The directory structure has been changed
>    2.Added lock protection for the ste_show and cd_show
> 
>    Others:
>    1.'arm_smmu_debugfs_remove' is added to remove the corresponding debugfs when SMMU device is removed
>    2.'arm_smmu_debugfs_remove_stream_table' is added to remove the corresponding stream_dir when device is removed
>    3.Use scoped_guard for locks that include return
>    4.Added 'open' and 'release' operations to prevent the device from being released during dump
>    5.Merged 'stream_table_create' and 'ste_show' into one patch
>    6.Some other clean code
> 
> - Link: https://lore.kernel.org/all/[email-masked]/
> 
> Qinxin Xia (5):
>    iommu/arm-smmu-v3: Add basic debugfs framework
>    iommu/arm-smmu-v3: Add register display to debugfs
>    iommu/arm-smmu-v3: Add Stream Table Entry display to debugfs
>    iommu/arm-smmu-v3: Add device symlink in stream table debugfs
>    iommu/arm-smmu-v3: Add Context Descriptor display to debugfs
> 
>   drivers/iommu/Kconfig                         |  11 +
>   drivers/iommu/arm/arm-smmu-v3/Makefile        |   1 +
>   .../arm/arm-smmu-v3/arm-smmu-v3-debugfs.c     | 571 ++++++++++++++++++
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  33 +-
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  32 +
>   5 files changed, 646 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-debugfs.c
> 

-- 
Thanks,
Qinxin