Re: [RFC PATCH 0/3] iommu/arm-smmu-v3: Add debug interfaces for SMMUv3

[Zhou Wang <wangzhou1@hisilicon.com>]

On 2021/1/29 17:06, Zhou Wang wrote:
> This RFC series is the followed patch of this discussion:
> https://www.spinics.net/lists/arm-kernel/msg866187.html. 
> 
> Currently there is no debug interface about SMMUv3 driver, which makes it
> not convenient when we want to dump some information, like the value of
> CD/STE, S1/S2 page table, SMMU registers or cmd/event/pri queues.
> 
> This series tries to add support of dumping CD/STE and page table. The
> interface design is that user sets device/pasid firstly by sysfs files
> and then read related sysfs file to get information:
> 
>  (currently only support PCI device)
>  echo <domain>:<bus>:<dev>.<fun> > /sys/kernel/debug/iommu/smmuv3/pci_dev
>  echo <pasid> > /sys/kernel/debug/iommu/smmuv3/pasid
>  
>  Then value in CD and STE can be got by:
>  cat /sys/kernel/debug/iommu/smmuv3/ste
>  cat /sys/kernel/debug/iommu/smmuv3/cd
>  
>  S1 and S2 page tables can be got by:
>  cat /sys/kernel/debug/iommu/smmuv3/pt_dump_s1
>  cat /sys/kernel/debug/iommu/smmuv3/pt_dump_s2
> 
> For STE, CD and page table, related device and pasid are set in pci_dev
> and pasid files as above.
> 
> First and second patch export some help functions or macros in arm-smmu-v3
> and io-pgtable-arm codes, so we can reuse them in debugfs.c. As a RFC, this
> series does not go further to dump SMMU registers and cmd/event/pri queues.
> I am not sure this series is in the right way, so let's post it out and have a
> discussion. Looking forward to any feedback.
> 
> Zhou Wang (3):
>   iommu/arm-smmu-v3: Export cd/ste get functions
>   iommu/io-pgtable: Export page table walk needed functions and macros
>   iommu/arm-smmu-v3: Add debug interfaces for SMMUv3
> 
>  drivers/iommu/Kconfig                       |  11 +
>  drivers/iommu/arm/arm-smmu-v3/Makefile      |   1 +
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  10 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  10 +
>  drivers/iommu/arm/arm-smmu-v3/debugfs.c     | 398 ++++++++++++++++++++++++++++
>  drivers/iommu/io-pgtable-arm.c              |  47 +---
>  drivers/iommu/io-pgtable-arm.h              |  43 +++
>  7 files changed, 475 insertions(+), 45 deletions(-)
>  create mode 100644 drivers/iommu/arm/arm-smmu-v3/debugfs.c
> 

Any comments about this series?

Best,
Zhou


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