From: Qinxin Xia <xiaqinxin@huawei•com>
To: <robin.murphy@arm•com>, <nicolinc@nvidia•com>, <will@kernel•org>,
<jpb@kernel•org>
Cc: <linux-arm-kernel@lists•infradead.org>, <iommu@lists•linux.dev>,
<xiaqinxin@huawei•com>, <wangzhou1@hisilicon•com>,
<prime.zeng@hisilicon•com>, <fanghao11@huawei•com>,
<jonathan.cameron@huawei•com>, <wuyifan50@huawei•com>,
<linuxarm@huawei•com>
Subject: [RFC PATCH v2 0/5] Add debugfs support for ARM SMMUv3
Date: Sat, 28 Mar 2026 18:17:01 +0800 [thread overview]
Message-ID: <20260328101706.3448655-1-xiaqinxin@huawei.com> (raw)
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/20260313104351.3502293-1-xiaqinxin@huawei.com/
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
--
2.33.0
WARNING: multiple messages have this Message-ID (diff)
From: Qinxin Xia <xiaqinxin@huawei•com>
To: <robin.murphy@arm•com>, <nicolinc@nvidia•com>, <will@kernel•org>,
<jpb@kernel•org>
Cc: <linux-arm-kernel@lists•infradead.org>, <iommu@lists•linux.dev>,
<xiaqinxin@huawei•com>, <wangzhou1@hisilicon•com>,
<prime.zeng@hisilicon•com>, <fanghao11@huawei•com>,
<jonathan.cameron@huawei•com>, <wuyifan50@huawei•com>,
<linuxarm@huawei•com>, <linux-kernel@vger•kernel.org>
Subject: [PATCH 0/5] Add debugfs support for ARM SMMUv3
Date: Wed, 20 May 2026 14:37:06 +0800 [thread overview]
Message-ID: <20260328101706.3448655-1-xiaqinxin@huawei.com> (raw)
Message-ID: <20260520063706.OZy2VlaLCfxiKwmjF7ONYoyIxuPlgKI2zqELkvCgREA@z> (raw)
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 RFCv2:
Address review comments from Nicolin Chen, kernel test robot, and Sashiko
automated review:
Build & kerneldoc fixes (patches 1-3):
- Add missing @unused parameter description to kerneldoc comments to fix
clang W=1 warnings reported by kernel test robot.
- Fix commit message: "driver.This" -> "driver. This" (patch 1).
Correctness fixes:
- Fix integer overflow: 1 << sid_bits -> 1ULL << sid_bits with %llu format,
preventing undefined behavior when SIDSIZE = 32 (patch 1).
- Fix EVTQ register access: use smmu->page1 instead of smmu->base for
EVTQ_PROD/EVTQ_CONS, which reside in register page 1 (patch 2).
- Fix STE config bit test: use proper cfg comparison instead of bitwise AND
on non-mask enumeration values, and extract S1ContextPtr from data[0]
instead of data[1] (patch 3).
Resource leak fixes (patches 1-5):
- Fix device reference leak: call put_device() when single_open() fails in
all open() callbacks (capabilities, registers, ste, cd).
- Fix dentry reference leak: add missing dput() after debugfs_lookup() in
stream table remove path (patch 3).
- Move kobject_get_path() outside the per-stream loop to avoid repeated
allocation (patch 4).
Locking & concurrency fixes:
- arm_smmu_debugfs_remove(): use scoped_guard() and move
debugfs_remove_recursive() outside the lock to avoid blocking other SMMU
instances on active VFS operations (patch 1).
- smmu_debugfs_ste_show(): change scoped_guard to guard(mutex) since the
entire function body is within the lock scope (patch 3).
- smmu_debugfs_cd_show(): change manual mutex_lock/unlock to
guard(mutex)(&arm_smmu_asid_lock) (patch 5).
Error handling fixes:
- Replace if (!debugfs_create_dir(...)) with IS_ERR() checks throughout,
since debugfs_create_dir() returns ERR_PTR on failure, not NULL
(patches 1, 3).
- Add NULL check for smmu->debugfs before dereference in stream table
create path (patch 3).
- Add NULL check for kzalloc_obj() result (patch 3).
Code style & cleanup:
- Directory tree comment: use ├── for last entry to avoid churn on
subsequent patches (patches 1-5).
- Fix tab/space alignment in directory tree comments (patches 1, 2).
- Reorder function parameters: @smmu first, @dev second (patch 3).
- Fix return statement indentation (patch 3).
- Move function declarations from #ifndef-static pattern to header file
(patch 3).
- Move char name[32] and snprintf() to function top for reuse by
iommu_device_sysfs_add() regardless of CONFIG_ARM_SMMU_V3_DEBUGFS
(patch 1).
- Adopt non-tab-aligned style for new struct members (patches 1, 3).
- Remove useless comments: "DebugFS Info" and "Reserved for future
extensions" (patches 1, 3).
- Remove spurious blank line (patch 3).
- Link: https://lore.kernel.org/all/20260328101706.3448655-1-xiaqinxin@huawei.com/
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 +
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-debugfs.c | 609 +++++++++++++++++++++
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 27 +-
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 30 +
5 files changed, 675 insertions(+), 3 deletions(-)
create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-debugfs.c
--
2.51.0
next reply other threads:[~2026-03-28 10:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-28 10:17 Qinxin Xia [this message]
2026-03-28 10:17 ` [RFC PATCH v2 1/5] iommu/arm-smmu-v3: Add basic debugfs framework Qinxin Xia
2026-03-30 10:46 ` Nicolin Chen
2026-04-02 3:50 ` Qinxin Xia
2026-03-28 10:17 ` [RFC PATCH v2 2/5] iommu/arm-smmu-v3: Add register display to debugfs Qinxin Xia
2026-03-30 11:25 ` Nicolin Chen
2026-03-28 10:17 ` [RFC PATCH v2 3/5] iommu/arm-smmu-v3: Add Stream Table Entry " Qinxin Xia
2026-04-04 5:43 ` Nicolin Chen
2026-03-28 10:17 ` [RFC PATCH v2 4/5] iommu/arm-smmu-v3: Add device symlink in stream table debugfs Qinxin Xia
2026-03-28 10:17 ` [RFC PATCH v2 5/5] iommu/arm-smmu-v3: Add Context Descriptor display to debugfs Qinxin Xia
2026-05-20 6:37 ` [PATCH 0/5] Add debugfs support for ARM SMMUv3 Qinxin Xia
2026-05-20 6:37 ` [PATCH 1/5] iommu/arm-smmu-v3: Add basic debugfs framework Qinxin Xia
2026-05-27 0:41 ` Nicolin Chen
2026-05-20 6:37 ` [PATCH 2/5] iommu/arm-smmu-v3: Add register display to debugfs Qinxin Xia
2026-05-27 1:28 ` Nicolin Chen
2026-05-20 6:37 ` [PATCH 3/5] iommu/arm-smmu-v3: Add Stream Table Entry " Qinxin Xia
2026-05-27 2:18 ` Nicolin Chen
2026-05-27 2:43 ` Nicolin Chen
2026-05-20 6:37 ` [PATCH 4/5] iommu/arm-smmu-v3: Add device symlink in stream table debugfs Qinxin Xia
2026-05-20 6:37 ` [PATCH 5/5] iommu/arm-smmu-v3: Add Context Descriptor display to debugfs Qinxin Xia
2026-05-27 2:40 ` Nicolin Chen
2026-05-27 0:07 ` [PATCH 0/5] Add debugfs support for ARM SMMUv3 Nicolin Chen
-- strict thread matches above, loose matches on Subject: below --
2026-03-28 10:09 [RFC PATCH v2 " Qinxin Xia
2026-03-28 10:14 ` Qinxin Xia
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