Re: [Xen-devel] VT-d faults with Integrated Intel graphics on 4.6

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 8/27/2015 7:03 PM, Konrad Rzeszutek Wilk wrote:
> On Thu, Aug 27, 2015 at 11:06:30AM +0800, Chen, Tiejun wrote:
> > On 8/25/2015 10:43 PM, Konrad Rzeszutek Wilk wrote:
> > >On Tue, Aug 25, 2015 at 02:55:31PM +0800, Chen, Tiejun wrote:
> > >>On 8/25/2015 8:19 AM, Tamas K Lengyel wrote:
> > >>>Hi everyone,
> > >>>I saw some people passingly mention this on the list before but just in
> > >>>case it has been missed, my serial is also being spammed with the following
> > >>>printouts with both Xen 4.6 RC1 and the latest staging build:
> > >>>
> > >>>...
> > >>>(XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr
> > >>>33487d7000, iommu reg = ffff82c000201000
> > >>>(XEN) [VT-D]DMAR: reason 06 - PTE Read access is not set
> > >>>(XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr
> > >>>33487d7000, iommu reg = ffff82c000201000
> > >>>(XEN) [VT-D]DMAR: reason 06 - PTE Read access is not set
> > >>>(XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr
> > >>>33487d7000, iommu reg = ffff82c000201000
> > >>>(XEN) [VT-D]DMAR: reason 06 - PTE Read access is not set
> > >>>(XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr
> > >>>33487d7000, iommu reg = ffff82c000201000
> > >>>(XEN) [VT-D]DMAR: reason 06 - PTE Read access is not set
> > >>>(XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr
> > >>>2610742000, iommu reg = ffff82c000201000
> > >>>(XEN) [VT-D]DMAR: reason 07 - Next page table ptr is invalid
> > >>>...
> > >>>
> > >>
> > >>What's your platform? BDW? And how much memory is set to your guest OS?
> > >
> > >Is see this as well. But oddly enough - only when I use the AMT feature
> > >(normally I just use serial console on the machine).
> > >
> > >The platform is             /DQ67SW, BIOS
> > >SWQ6710H.86A.0066.2012.1105.1504 11/05/2012
> > >
> > >There is no guest OS - this is initial domain. And I boot with 2GB:
> > >  Released 0 page(s)
> > >
> > >Xen: [mem 0x0000000000000000-0x0000000000099fff] usable
> > >Xen: [mem 0x000000000009a800-0x00000000000fffff] reserved
> > >Xen: [mem 0x0000000000100000-0x000000001fffffff] usable
> > >Xen: [mem 0x0000000020000000-0x00000000201fffff] reserved
> > >Xen: [mem 0x0000000020200000-0x000000003fffffff] usable
> > >Xen: [mem 0x0000000040000000-0x00000000401fffff] reserved
> > >Xen: [mem 0x0000000040200000-0x0000000080465fff] usable
> > >Xen: [mem 0x0000000080466000-0x000000009e855fff] unusable
> > >Xen: [mem 0x000000009e856000-0x000000009e85efff] ACPI data
> > >Xen: [mem 0x000000009e85f000-0x000000009e8a9fff] ACPI NVS
> > >Xen: [mem 0x000000009e8aa000-0x000000009e8b1fff] unusable
> > >Xen: [mem 0x000000009e8b2000-0x000000009e9a4fff] reserved
> > >Xen: [mem 0x000000009e9a5000-0x000000009e9a6fff] unusable
> > >Xen: [mem 0x000000009e9a7000-0x000000009ebc5fff] reserved
> > >Xen: [mem 0x000000009ebc6000-0x000000009ebc6fff] unusable
> > >Xen: [mem 0x000000009ebc7000-0x000000009ebd6fff] reserved
> > >Xen: [mem 0x000000009ebd7000-0x000000009ebf4fff] ACPI NVS
> > >Xen: [mem 0x000000009ebf5000-0x000000009ec18fff] reserved
> > >Xen: [mem 0x000000009ec19000-0x000000009ec5bfff] ACPI NVS
> > >Xen: [mem 0x000000009ec5c000-0x000000009ee7bfff] reserved
> > >Xen: [mem 0x000000009ee7c000-0x000000009effffff] unusable
> > >Xen: [mem 0x000000009f800000-0x00000000bf9fffff] reserved
> > >Xen: [mem 0x00000000fec00000-0x00000000fec00fff] reserved
> > >Xen: [mem 0x00000000fed1c000-0x00000000fed3ffff] reserved
> > >Xen: [mem 0x00000000fed90000-0x00000000fed91fff] reserved
> > >Xen: [mem 0x00000000fee00000-0x00000000feefffff] reserved
> > >Xen: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
> > >Xen: [mem 0x0000000100000000-0x000000043e5fffff] unusable
> > >
> > >>
> > >>Just at first glance to fault address, this seems be issued from some
> >
> > As you see those fault addresses are out of the normal memory range  here.
> >
> > >>known erratas on BDS and SKL.
> > >
> > >I am runnig v4.2-rc8.
> >
> > So I really doubt this is related to some erratas. Currently the pre-fetch
> > unit of IOMMU unit dedicated to IGD can't work well on some platforms, so
> > you can see these wired faults.
> Do you have some ideas for a solution/patch?
I can't reproduce this on my BDW. And this is my assumption as well. So 
could anyone provide a log with iommu=debug?
Thanks
Tiejun

> Thanks!
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