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SubjectRe: [iommu/vt] c9ac3b69cf: WARNING:at_drivers/iommu/intel-iommu.c:#dmar_parse_one_rmrr
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Date
Hi -

On 2/3/20 4:10 AM, kernel test robot wrote:
> FYI, we noticed the following commit (built with gcc-7):
>
> commit: c9ac3b69cfdbc46a0504fa353b5126827e4b0bdb ("iommu/vt-d: skip RMRR entries that fail the sanity check")
> https://github.com/0day-ci/linux/commits/Barret-Rhoden/iommu-vt-d-bad-RMRR-workarounds/20200109-051817

This looks like your system's firmware might be buggy, which is what the
warning is all about.

From the kmesg:

> kern :info : [ 2.912758] DMAR: RMRR base: 0x0000009f271000 end: 0x0000009f290fff
> kern :info : [ 2.919226] DMAR: RMRR base: 0x000000a1800000 end: 0x000000a3ffffff
> kern :err : [ 2.925692] DMAR: [Firmware Bug]: No firmware reserved region can cover this RMRR [0x00000000a1800000-0x00000000a3ffffff], contact BIOS vendor for fixes
> kern :warn : [ 2.939636] ------------[ cut here ]------------
> kern :warn : [ 2.944436] Your BIOS is broken; bad RMRR [0x00000000a1800000-0x00000000a3ffffff]
> BIOS vendor: Dell Inc.; Ver: 1.2.8; Product Version:


The e820 map has this:

> kern :info : [ 0.000000] BIOS-e820: [mem 0x00000000a0000000-0x00000000a00fffff] reserved
> kern :info : [ 0.000000] BIOS-e820: [mem 0x00000000f8000000-0x00000000fbffffff] reserved
> kern :info : [ 0.000000] BIOS-e820: [mem 0x00000000fe000000-0x00000000fe010fff] reserved

The region 0xa1800000-0xa3ffffff isn't explicitly reserved (it's not
listed at all), which the IOMMU-folk say is the fault of the firmware.

My commit made it so that it merely spits out a warning, instead of
failing to use the IOMMU at all.

Thanks,

Barret

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