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Message-ID: <951ae02a-1d43-444a-a2f3-5f9f56fce0fd@amd.com> Date: Fri, 7 Mar 2025 13:47:08 +0530 From: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@....com> To: joro@...tes.org, suravee.suthikulpanit@....com, will@...nel.org, robin.murphy@....com, linux-kernel@...r.kernel.org, iommu@...ts.linux.dev Cc: vasant.hegde@....com Subject: Re: [PATCH v3 0/8] Introduce debugfs support in IOMMU Hi, I hope you're doing well. Just a friendly reminder to kindly review the patches at your earliest convenience. Your feedback is greatly appreciated. Thanks Dheeraj On 2/6/2025 11:29 AM, Dheeraj Kumar Srivastava wrote: > From: root <root@...DHSRIVAS.amd.com> > > Introducing debugfs support in AMD/IOMMU driver that will allow > userspace to dump below IOMMU information > 1) MMIO and Capability register per IOMMU > 2) Command buffer > 3) Device table entry > 4) Interrupt remapping table entry > > Analyzing contents of IOMMU data structures helps in understanding IOMMU > capabilities and behavior and debug issues faster. > > 1. MMIO and Capability registers - Add support to dump MMIO and Capability > registers per IOMMU. > > Example: > a. Write MMIO register offset to dump it > $ echo 0x18 > /sys/kernel/debug/iommu/amd/iommu00/mmio > $ cat /sys/kernel/debug/iommu/amd/iommu00/mmio > > Output: > $ 0x0003f48d > > b. Write capability register offset to dump it > $ echo 0x10 > /sys/kernel/debug/iommu/amd/iommu00/capability > $ cat /sys/kernel/debug/iommu/amd/iommu00/capability > > Output: > $ 0x00203040 > > 2. Command buffer - Add support to dump per IOMMU command buffer. > > Example: > a. cat /sys/kernel/debug/iommu/amd/iommu00/cmdbuf > > Output: > CMD Buffer Head Offset:339 Tail Offset:339 > 0: 00835001100000010000990000000000 > 1: 0000000030000005fffff0037fffffff > 2: 00835001100000010000990100000000 > 3: 0000000030000005fffff0037fffffff > 4: 00835001100000010000990200000000 > ................................... > ................................... > ................................... > > 3. Device table - Add support to dump device table per IOMMU. > > Example: > a. Write device id to dump device table entry for that device > $ echo 0000:01:00.0 > /sys/kernel/debug/iommu/amd/devid > $ cat /sys/kernel/debug/iommu/amd/devid > > Output: > 0000:01:00.0 > > Dump the device table entry for the input given > $ 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 > > b. Write device id to dump device table entry for that device > $ echo 01:00.0 > /sys/kernel/debug/iommu/amd/devid > $ cat /sys/kernel/debug/iommu/amd/devid > > Output: > 0000:01:00.0 > > Dump the device table entry for the input given > $ 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 > > 4. Interrupt remapping table - Add support to dump IRT table valid entries in > "iommu_irqtbl" file. This supports user input to dump IRT entry for a > specific pci device. > > Example: > a. Write device id to dump device table entry for that device > $ echo 0000:01:00.0 > /sys/kernel/debug/iommu/amd/devid > $ cat /sys/kernel/debug/iommu/amd/devid > > Output: > 0000:01:00.0 > > Dump the device table entry for the input given > $ cat /sys/kernel/debug/iommu/amd/irtbl > > Output: > DeviceId 0000:01:00.0 > IRT[0000] 00000000000000200000000000000241 > IRT[0001] 00000000000000200000000000000841 > IRT[0002] 00000000000000200000000000002041 > IRT[0003] 00000000000000200000000000008041 > IRT[0004] 00000000000000200000000000020041 > .......................................... > .......................................... > .......................................... > > b. Write device id to dump device table entry for that device > $ echo 01:00.0 > /sys/kernel/debug/iommu/amd/devid > $ cat /sys/kernel/debug/iommu/amd/devid > > Output: > 0000:01:00.0 > > Dump the device table entry for the input given > $ cat /sys/kernel/debug/iommu/amd/irttbl > > Output: > Device 0000:01:00.0 > IRT[0000] 00000000000000200000000000000241 > IRT[0001] 00000000000000200000000000000841 > IRT[0002] 00000000000000200000000000002041 > IRT[0003] 00000000000000200000000000008041 > IRT[0004] 00000000000000200000000000020041 > .......................................... > .......................................... > .......................................... > > Open question:[Suggestion from Bjorn Helgaas] Instead of using device-id input with > "/sys/kernel/debug/iommu/amd/devid", can we have something like other drivers > have "/sys/kernel/debug/iommu/amd/<bdf>/". > > Each "/sys/kernel/debug/iommu/amd/<bdf>/" will have "devtbl" and "irqtbl" files > for device table and interrupt remapping table dump file. > > > Changes since v2: > -> Patch 2/8 and 3/8: Use single file mmio and capability for input and output registers > offset and registers dump respctively. > -> Patch 8/8: Correct path for files "irqtbl" and "devtbl" in Documentation > > Changes since v1: > -> Patch 2/8 and 3/8: Use kstrtou32_from_user() instead of memdup_user_nul() --> kstrtou32() > -> Patch 4/8: Dump command buffer head and tail offset instead of head and tail pointer registers. > -> Patch 8/8: Fix bot reported warning on v1 upstream. > > Dheeraj Kumar Srivastava (8): > iommu/amd: Refactor AMD IOMMU debugfs initial setup > iommu/amd: Add debugfs support to dump IOMMU MMIO registers > iommu/amd: Add debugfs support to dump IOMMU Capability registers > iommu/amd: Add debugfs support to dump IOMMU command buffer > iommu/amd: Add support for device id user input > iommu/amd: Add debugfs support to dump device table > iommu/amd: Add debugfs support to dump IRT Table > iommu/amd: Add documentation for AMD IOMMU debugfs support > > Documentation/ABI/testing/debugfs-amd-iommu | 114 +++++++ > drivers/iommu/amd/amd_iommu.h | 4 +- > drivers/iommu/amd/amd_iommu_types.h | 7 + > drivers/iommu/amd/debugfs.c | 350 +++++++++++++++++++- > drivers/iommu/amd/init.c | 5 +- > drivers/iommu/amd/iommu.c | 7 - > 6 files changed, 466 insertions(+), 21 deletions(-) > create mode 100644 Documentation/ABI/testing/debugfs-amd-iommu >
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