Re: DMAR and DRHD errors[DMAR:[fault reason 06] PTE Read access is not set] Vt-d & intel_iommu

[Don Dutile <ddutile@redhat.com>]

On 12/13/2012 04:50 AM, Jason Gao wrote:
> Dear List:
>
> Description of problem:
> After installed Centos 6.3(RHEL6.3) on my Dell R710(lastest
> bios:Version: 6.3.0,Release Date: 07/24/2012) server,and updated
> lastest kernel "2.6.32-279.14.1.el6.x86_64",I want to use the Intel
> 82576 ET Dual Port nic's SR-IOV feature,assigning VFs to kvm guest
>
> appended kernel boot parameter: intel_iommu=on,after boot with the
> following messages:
>
> Dec 13 16:58:15 2 kernel: DRHD: handling fault status reg 2
> Dec 13 16:58:15 2 kernel: DMAR:[DMA Read] Request device [03:00.0]
> fault addr ffe65000
> Dec 13 16:58:15 2 kernel: DMAR:[fault reason 06] PTE Read access is not set
> Dec 13 16:58:15 2 kernel: DRHD: handling fault status reg 102
> Dec 13 16:58:15 2 kernel: DMAR:[DMA Read] Request device [03:00.0]
> fault addr ffe8a000
> Dec 13 16:58:15 2 kernel: DMAR:[fault reason 06] PTE Read access is not set
> Dec 13 16:58:15 2 kernel: scsi 0:0:32:0: Enclosure         DP
> BACKPLANE        1.07 PQ: 0 ANSI: 5
> Dec 13 16:58:15 2 kernel: DRHD: handling fault status reg 202
> Dec 13 16:58:15 2 kernel: DMAR:[DMA Read] Request device [03:00.0]
> fault addr ffe89000
> Dec 13 16:58:15 2 kernel: DMAR:[fault reason 06] PTE Read access is not set
>
> full dmesg detail:
>     http://pastebin.com/BzFQV0jU
> lspci -vvv full detail:
>     http://pastebin.com/9rP2d1br
>
>
> it's a production server,and I'm not sure if this is a critical
> problem,how to fix it,any help would be greatly appreciated.

DMAR table does not have an entry for this device to this region.
Once the driver reconfigs/resets the device to stop polling bios-boot
cmd rings and use (new) OS (dma-mapped) rings, there's a period of time
during this transition that the hw is babbling away to an area that is no
longer mapped.
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