Messages in this thread | | | Date | Tue, 11 Jul 2023 10:52:23 +0800 | Subject | Re: [PATCH 0/5] iommu/vt-d: debugfs: Enhancements to IOMMU debugfs | From | Baolu Lu <> |
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On 2023/7/11 9:40, Liu, Jingqi wrote: > On 7/4/2023 3:54 PM, Tian, Kevin wrote: >>> From: Liu, Jingqi <jingqi.liu@intel.com> >>> Sent: Monday, July 3, 2023 10:37 PM >>> >>> On 7/3/2023 3:15 PM, Tian, Kevin wrote: >>>>> From: Liu, Jingqi <jingqi.liu@intel.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 >>> Thanks. >>> >>> Do you mean create a directory for each device, whether it supports >>> PASID or not ? >> every device has PASID#0 valid, i.e. RID2PASID. > Sorry for the late response. > Got it. Thanks. >>> Seems the PASID can be assigned at runtime. >>> So it needs to support creating debugfs file at runtime in IOMMU driver. >>> Looks like this requires modifying IOMMU driver. >>> >> Isn't this patch trying to modify the driver? > I just tried not to modify the driver except debugfs. > I'll try this implementation.
I'd second Kevin's suggestion.
If you check how usb xhci dumps its contexts for devices, you can see the similar scheme.
# ls /sys/kernel/debug/usb/xhci/0000:00:14.0/devices 01 02 03 04 05
In our case, pasid 0 is special which denotes the domain attached to the RID.
Best regards, baolu
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