> -----Original Message-----
> From: Joerg Roedel [mailto:[email protected]]
> 
> [Adding the Emulex driver developers to Cc for some input on the device,
>  and why it might use wrong request ids]
> 
> On Mon, Aug 25, 2014 at 02:44:59PM +0800, Yijing Wang wrote:
> > We found some strange devices in HP C7000 and Huawei Storage Server.
> These
> > devices can not be enumerated by OS, but they still did DMA read/write
> > without OS management. Because iommu will not create the DMA
> mapping for
> > these devices, the DMA read/write will be blocked by iommu hardware.

Hi Wang, could you please share the lspci -vvv output and the kernel log too.
Thanks!

> >
> > Eg.
> > in HP C7000:
> >  \-[0000:00]-+-00.0  Intel Corporation Xeon E5/Core i7 DMI2
> >              +-01.0-[11]--
> >                      +-01.1-[02]--
> >                      +-02.0-[04]--+-00.0  Emulex Corporation OneConnect
> 10Gb NIC (be3)
> >              |            +-00.1  Emulex Corporation OneConnect 10Gb NIC 
> > (be3)
> >              |            +-00.2  Emulex Corporation OneConnect 10Gb iSCSI
> Initiator (be3)
> >              |            \-00.3  Emulex Corporation OneConnect 10Gb iSCSI
> Initiator (be3)
> >              +-02.1-[12]--
> > Kernel only found four devices in bus 0x04, but we found following DMA
> errors in dmesg.
> >
> > [ 1438.477262] DRHD: handling fault status reg 402
> > [ 1438.498278] DMAR:[DMA Write] Request device [04:00.4] fault addr
> bdf70000
> > [ 1438.498280] DMAR:[fault reason 02] Present bit in context entry is clear
> > [ 1438.566458] DMAR:[DMA Write] Request device [04:00.5] fault addr
> bdf70000
> > [ 1438.566460] DMAR:[fault reason 02] Present bit in context entry is clear
> > [ 1438.635211] DMAR:[DMA Write] Request device [04:00.6] fault addr
> bdf70000
> > [ 1438.635213] DMAR:[fault reason 02] Present bit in context entry is clear
> > [ 1438.703849] DMAR:[DMA Write] Request device [04:00.7] fault addr
> bdf70000
> > [ 1438.703851] DMAR:[fault reason 02] Present bit in context entry is clear
> >
> > This patch add a kernel boot command parameter
> iommu=pt_force=domain:busnum
> > that based iommu identity mapping and force to create identity for all
> devfn in
> > the specific bus number to fix this issue.
> 
> No! If the device really uses request-ids it shouldn't use please add a
> DMA alias quirk instead. A new kernel parameter will not work out of the
> box for other users of this device.
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