Re: [PATCH] iommu/vt-d: Fix scatterlist offset handling

[Casey Leedom]

| From: Harsh Jain <Harsh@xxxxxxxxxxx>
| Sent: Friday, September 29, 2017 1:14:45 AM
|     
| Robin,
| 
| I tried running patch on our test setup.
| 
| With "intel_iommu=on" : I can see single occurrence of DMAR Write failure
| on perf traffic with 10 thread.
| 
| [  749.616480] perf: interrupt took too long (3203 > 3202), lowering kernel.perf_event_max_sample_rate to 62000
| [  852.500671] DMAR: DRHD: handling fault status reg 2
| [  852.506039] DMAR: [DMA Write] Request device [02:00.4] fault addr ef919000 [fault reason 05] PTE Write access is not set
| [root@heptagon linux_t4_build]# cat /proc/cmdline
| BOOT_IMAGE=/vmlinuz-4.9.51+ root=UUID=ccbb7f18-b3f0-43df-89de-07521e9c02fe ro intel_iommu=on crashkernel=auto rhgb quiet rhgb quiet console=ttyS0,115200, console=tty0 LANG=en_US.UTF-8

Harsh. Can you provide the debugging information for that one DMA FAILURE
trace?  It May be yet another corner case in __domain_mapping() or a
different path.

| With intel_iommu=sp_off : It works fine for more than 30 minutes without
| any issues.

I think that even without Robin's patch using intel_iommu=sp_off worked
without errors, right?

Casey