linux-kernel - RE: [PATCH 0/5] iommu/vt-d: debugfs: Enhancements to IOMMU debugfs

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Date:   Mon, 3 Jul 2023 07:15:04 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     "Liu, Jingqi" <jingqi.liu@...el.com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 0/5] iommu/vt-d: debugfs: Enhancements to IOMMU debugfs

> From: Liu, Jingqi <jingqi.liu@...el.com>
> Sent: Sunday, June 25, 2023 11:05 PM
> 
> The original debugfs only dumps all IOMMU page tables without pasid
> supported. It traverses all devices on the pci bus, then dumps all page
> tables based on device domains. This traversal is from software
> perspective.
> 
> This series dumps page tables by traversing root tables, context tables,
> pasid directories and pasid tables from hardware perspective. By
> specifying source identifier and PASID, it supports dumping specified
> page table or all page tables in legacy mode or scalable mode.
> 
> For a device that only supports legacy mode, specify the source
> identifier, and search the root table and context table to dump its
> page table. It does not support to specify PASID.
> 
> For a device that supports scalable mode, specify a
> {source identifier, PASID} pair and search the root table, context table
> and pasid table to dump its page table.  If the pasid is not specified,
> it is set to RID_PASID.
> 
> Switch to dump all page tables by specifying "auto".
> 
> Examples are as follows:
> 1) Dump the page table of device "00:1f.0" that only supports legacy
> mode.
> 
> $ sudo echo 00:1f.0 >
> /sys/kernel/debug/iommu/intel/domain_translation_struct
> $ sudo cat /sys/kernel/debug/iommu/intel/domain_translation_struct
> Device 0000:00:1f.0 @0x105407000
> IOVA_PFN                PML5E                   PML4E
> 0x0000000000000 |       0x0000000000000000      0x0000000105408003
> 0x0000000000001 |       0x0000000000000000      0x0000000105408003
> 0x0000000000002 |       0x0000000000000000      0x0000000105408003
> 0x0000000000003 |       0x0000000000000000      0x0000000105408003
> 
> PDPE                    PDE                     PTE
> 0x0000000105409003      0x000000010540a003      0x0000000000000003
> 0x0000000105409003      0x000000010540a003      0x0000000000001003
> 0x0000000105409003      0x000000010540a003      0x0000000000002003
> 0x0000000105409003      0x000000010540a003      0x0000000000003003
> 
> [...]
> 
> 2) Dump the page table of device "00:0a.0" with pasid "2".
> 
> $ sudo echo 00:0a.0,2 >
> /sys/kernel/debug/iommu/intel/domain_translation_struct
> $ sudo cat /sys/kernel/debug/iommu/intel/domain_translation_struct

What about creating a directory layout per {dev, pasid} so the user can
easily figure out and dump?

e.g.

/sys/kernel/debug/iommu/intel/00:0a.0/0/domain_translation_struct
/sys/kernel/debug/iommu/intel/00:0a.0/2/domain_translation_struct

> Device 0000:00:0a.0 with pasid 2 @0x1083d7000
> IOVA_PFN                PML5E                   PML4E
> 0x0000000000000 |       0x0000000000000000      0x0000000106aaa003
> 0x0000000000001 |       0x0000000000000000      0x0000000106aaa003
> 0x0000000000002 |       0x0000000000000000      0x0000000106aaa003
> 0x0000000000003 |       0x0000000000000000      0x0000000106aaa003
> 
> PDPE                    PDE                     PTE
> 0x000000010a819003      0x000000010a7aa003      0x0000000129800003
> 0x000000010a819003      0x000000010a7aa003      0x0000000129801003
> 0x000000010a819003      0x000000010a7aa003      0x0000000129802003
> 0x000000010a819003      0x000000010a7aa003      0x0000000129803003
> 
> [...]
> 
> 3) Dump all page tables:
> $ sudo echo "auto" >
> /sys/kernel/debug/iommu/intel/domain_translation_struct
> $ sudo cat /sys/kernel/debug/iommu/intel/domain_translation_struct
> [...]
> 
> Device 0000:00:02.0 @0x103072000
> IOVA_PFN                PML5E                   PML4E
> 0x000000008d800 |       0x0000000000000000      0x0000000103073003
> 0x000000008d801 |       0x0000000000000000      0x0000000103073003
> 
> PDPE                    PDE                     PTE
> 0x0000000103074003      0x0000000103075003      0x000000008d800003
> 0x0000000103074003      0x0000000103075003      0x000000008d801003
> 
> [...]
> 
> Device 0000:00:0a.0 with pasid 2 @0x10a0b6000
> IOVA_PFN                PML5E                   PML4E
> 0x0000000000000 |       0x0000000000000000      0x00000001072d2003
> 0x0000000000001 |       0x0000000000000000      0x00000001072d2003
> 
> PDPE                    PDE                     PTE
> 0x0000000107d6e003      0x00000001161d4003      0x00000001bdc00003
> 0x0000000107d6e003      0x00000001161d4003      0x00000001bdc01003
> 
> [...]
> 
> Thanks,
> Jingqi
> 
> Jingqi Liu (5):
>   iommu/vt-d: debugfs: Define domain_translation_struct file ops
>   iommu/vt-d: debugfs: Support specifying source identifier and PASID
>   iommu/vt-d: debugfs: Dump the corresponding page table of a pasid
>   iommu/vt-d: debugfs: Support dumping a specified page table
>   iommu/vt-d: debugfs: Dump entry pointing to huge page
> 
>  drivers/iommu/intel/debugfs.c | 361 ++++++++++++++++++++++++++++++----
>  1 file changed, 326 insertions(+), 35 deletions(-)
> 
> --
> 2.21.3