[dpdk-dev] IXGBE, IOMMU DMAR DRHD handling fault issue

Ravi Kerur rkerur at gmail.com
Thu Feb 1 20:26:29 CET 2018


On Thu, Feb 1, 2018 at 2:10 AM, Burakov, Anatoly <anatoly.burakov at intel.com>
wrote:

> On 31-Jan-18 9:51 PM, Ravi Kerur wrote:
>
>>
>> Hi Anatoly,
>>
>> Thanks. I am following wiki link below which uses vIOMMU with DPDK as a
>> use-case and instantiate VM as specified with Q35 chipset in Qemu.
>>
>> https://wiki.qemu.org/Features/VT-d
>>
>> Qemu-version is 2.11
>> Host kernel 4.9
>> Guest kernel 4.4
>>
>> I can only guess that guest kernel needs an upgrade in my setup to work
>> correctly, if versions on my setup rings a bell on not having support
>> kindly let me know.
>>
>> When 'modprobe vfio enable_unsafe_noiommu_node=Y' is executed on guest I
>> get following error
>> ...
>> vfio: unknown parameter 'enable_unsafe_noiommu_node' ignored
>> ...
>>
>> in guest.
>>
>> Thanks.
>>
>
>
AFAIK kernel 4.4 should have noiommu mode - it was introduced in 3.1x days.
> However, in order for that to work, kernel also has to be built with this
> mode enabled. My guess is, whoever is the supplier of your kernel, did not
> do that. You should double-check the kernel configuration of your
> distribution.
>
> However, if you have vIOMMU in QEMU, you shouldn't need noiommu mode -
> "regular" vfio should work fine. noiommu mode should only be needed if you
> know you don't have IOMMU enabled in your kernel, and even if you can't
> enable it, you can still use igb_uio.
>
> Hi Anatoly,

Do you suggest I take this discussion to kvm/qemu mailing list as I am not
sure which component has the issue? I check dmesg for BIOS physical memory
map and address reported as fault by DMAR is reported by BIOS as usable on
both host and vm.

[ 4539.597737] DMAR: [DMA Read] Request device [04:10.0] fault addr *33a128000
*[fault reason 06] PTE Read access is not set

dmesg | grep BIOS
[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009afff] usable
[    0.000000] BIOS-e820: [mem 0x000000000009b000-0x000000000009ffff]
reserved
[    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff]
reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007938afff] usable
[    0.000000] BIOS-e820: [mem 0x000000007938b000-0x000000007994bfff]
reserved
[    0.000000] BIOS-e820: [mem 0x000000007994c000-0x000000007999cfff] ACPI
data
[    0.000000] BIOS-e820: [mem 0x000000007999d000-0x0000000079f7dfff] ACPI
NVS
[    0.000000] BIOS-e820: [mem 0x0000000079f7e000-0x000000007bd37fff]
reserved
[    0.000000] BIOS-e820: [mem 0x000000007bd38000-0x000000007bd38fff] usable
[    0.000000] BIOS-e820: [mem 0x000000007bd39000-0x000000007bdbefff]
reserved
[    0.000000] BIOS-e820: [mem 0x000000007bdbf000-0x000000007bffffff] usable
[    0.000000] BIOS-e820: [mem 0x000000007c000000-0x000000008fffffff]
reserved
[    0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed44fff]
reserved
[    0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff]
reserved
[*    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000407fffffff]
usable*

Kindly let me know your inputs.

Thanks.


-- 
> Thanks,
> Anatoly
>


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