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Mountain mystic
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Joined: 26 Oct 2018
Posts: 21
Location: 39°6′32″N 76°46′17″W

PostPosted: Thu Nov 15, 2018 12:20 am    Post subject: DMAR fault, IOMMU issues? Reply with quote

Hi everyone,
I am having an extremely large amount of errors in dmesg (over 2000 for 5 days of uptime).
Here is the kernel config: https://pastebin.com/yw9ukJhY

I suspect these are the related section in the configuration:
Code:
CONFIG_IOMMU_IOVA=y
CONFIG_AMD_IOMMU=y
# CONFIG_AMD_IOMMU_V2 is not set
CONFIG_DMAR_TABLE=y
CONFIG_INTEL_IOMMU=y
# CONFIG_INTEL_IOMMU_SVM is not set
CONFIG_INTEL_IOMMU_DEFAULT_ON=y
CONFIG_INTEL_IOMMU_FLOPPY_WA=y
CONFIG_IRQ_REMAP=y


There seems to be a related Fedora bug: https://bugzilla.redhat.com/show_bug.cgi?id=1573021 Does anyone have any related issues I am trying to find out if this is a kernel (and therefore upstream) bug.

Code:
[84580.107753] dmar_fault: 173 callbacks suppressed
[84580.107754] DMAR: DRHD: handling fault status reg 2
[84580.107757] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[84580.109593] DMAR: DRHD: handling fault status reg 2
[84580.109596] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85169.823575] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null)
[85201.510779] DMAR: DRHD: handling fault status reg 2
[85201.510783] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.523535] DMAR: DRHD: handling fault status reg 2
[85201.523539] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.790450] DMAR: DRHD: handling fault status reg 2
[85201.790456] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.790739] DMAR: DRHD: handling fault status reg 2
[85201.790743] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.800804] DMAR: DRHD: handling fault status reg 2
[85201.800807] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85419.581626] DMAR: DRHD: handling fault status reg 2
[85419.581630] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85419.590547] DMAR: DRHD: handling fault status reg 2
[85419.590550] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85420.027229] DMAR: DRHD: handling fault status reg 2
[85420.027234] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85420.027405] DMAR: DRHD: handling fault status reg 2
[85420.027409] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85420.037493] DMAR: DRHD: handling fault status reg 2
[85420.037498] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set

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ali3nx
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Joined: 21 Sep 2003
Posts: 612
Location: Vancouver, Canada

PostPosted: Thu Nov 15, 2018 3:31 am    Post subject: Re: DMAR fault, IOMMU issues? Reply with quote

Mountain mystic wrote:
Hi everyone,
I am having an extremely large amount of errors in dmesg (over 2000 for 5 days of uptime).
Here is the kernel config: https://pastebin.com/yw9ukJhY

I suspect these are the related section in the configuration:
Code:
CONFIG_IOMMU_IOVA=y
CONFIG_AMD_IOMMU=y
# CONFIG_AMD_IOMMU_V2 is not set
CONFIG_DMAR_TABLE=y
CONFIG_INTEL_IOMMU=y
# CONFIG_INTEL_IOMMU_SVM is not set
CONFIG_INTEL_IOMMU_DEFAULT_ON=y
CONFIG_INTEL_IOMMU_FLOPPY_WA=y
CONFIG_IRQ_REMAP=y


There seems to be a related Fedora bug: https://bugzilla.redhat.com/show_bug.cgi?id=1573021 Does anyone have any related issues I am trying to find out if this is a kernel (and therefore upstream) bug.

Code:
[84580.107753] dmar_fault: 173 callbacks suppressed
[84580.107754] DMAR: DRHD: handling fault status reg 2
[84580.107757] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[84580.109593] DMAR: DRHD: handling fault status reg 2
[84580.109596] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85169.823575] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null)
[85201.510779] DMAR: DRHD: handling fault status reg 2
[85201.510783] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.523535] DMAR: DRHD: handling fault status reg 2
[85201.523539] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.790450] DMAR: DRHD: handling fault status reg 2
[85201.790456] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.790739] DMAR: DRHD: handling fault status reg 2
[85201.790743] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85201.800804] DMAR: DRHD: handling fault status reg 2
[85201.800807] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85419.581626] DMAR: DRHD: handling fault status reg 2
[85419.581630] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85419.590547] DMAR: DRHD: handling fault status reg 2
[85419.590550] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85420.027229] DMAR: DRHD: handling fault status reg 2
[85420.027234] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85420.027405] DMAR: DRHD: handling fault status reg 2
[85420.027409] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set
[85420.037493] DMAR: DRHD: handling fault status reg 2
[85420.037498] DMAR: [DMA Write] Request device [00:02.0] fault addr f9b78000 [fault reason 05] PTE Write access is not set


Depending on which cpu you have some cpu's have eratta bugs with iommu. My 1st gen intel i7-920 when dmar by default is enabled is completely unusable and produces a very prominent cpu eratta bug warning in dmesg.

Check dmesg and report back with the pc hardware your using. iommu remapping or CONFIG_INTEL_IOMMU_DEFAULT_ON=y is not well supported on all devices, some devices will hard lock when using iommu remapping and some cpu stability issues can be potentially resolved with cpu microcode updates compiled into the kernel binary.
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bunder
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PostPosted: Thu Nov 15, 2018 6:04 am    Post subject: Reply with quote

I've seen this before, try adding intel_iommu=on,igfx_off to your kernel cmdline, I don't think this happens anymore on 4.19.
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tholin
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Joined: 04 Oct 2008
Posts: 176

PostPosted: Thu Nov 15, 2018 9:32 am    Post subject: Reply with quote

Device [00:02.0] is the igpu right? Since you get so many errors I assume you use it but if not disable it in bios. IOMMU and intel igpu are known to be problematic but intel's devs don't really care about it. You'll just get the recommendation to use intel_iommu=igfx_off to work around the problem. The various IOMMU related problems are dumped into this bug https://bugs.freedesktop.org/show_bug.cgi?id=89360
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