Re: [Xen-devel] Multi-bridged PCIe devices (Was: Re: iommuu/vt-d issues with LSI MegaSAS (PERC5i))

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of Gordan Bobic
> Sent: Tuesday, January 07, 2014 6:44 PM
> To: Andrew Cooper
> Cc: xen-devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] Multi-bridged PCIe devices (Was: Re: iommuu/vt-d
> issues with LSI MegaSAS (PERC5i))
> 
> On 2014-01-07 10:38, Andrew Cooper wrote:
> > On 07/01/14 10:35, Gordan Bobic wrote:
> >> On 2014-01-07 03:17, Zhang, Yang Z wrote:
> >>> Konrad Rzeszutek Wilk wrote on 2014-01-07:
> >>>>> Which would look like this:
> >>>>>
> >>>>> C220 ---> Tundra Bridge -----> (HB6 PCI bridge -> Brooktree BDFs)
> >>>>> on the card
> >>>>>           \--------------> IEEE-1394a
> >>>>>
> >>>>> I am actually wondering if this 07:00.0 device is the one that
> >>>>> reports itself as 08:00.0 (which I think is what you alluding to
> >>>>> Jan)
> >>>>>
> >>>>
> >>>> And to double check that theory I decided to pass in the IEEE-1394a
> >>>> to a guest:
> >>>>
> >>>>            +-1c.5-[07-08]----00.0-[08]----03.0  Texas Instruments
> >>>> TSB43AB22A IEEE-1394a-2000 Controller (PHY/Link) [iOHCI-Lynx]
> >>>>
> >>>>
> >>>> (XEN) [VT-D]iommu.c:885: iommu_fault_status: Fault Overflow (XEN)
> >>>> [VT-D]iommu.c:887: iommu_fault_status: Primary Pending Fault (XEN)
> >>>> [VT-D]iommu.c:865: DMAR:[DMA Read] Request device [0000:08:00.0]
> >>>> fault
> >>>> addr 370f1000, iommu reg = ffff82c3ffd53000 (XEN) DMAR:[fault reason
> >>>> 02h] Present bit in context entry is clear (XEN) print_vtd_entries:
> >>>> iommu ffff83083d4939b0 dev 0000:08:00.0 gmfn 370f1 (XEN)
> >>>> root_entry
> >>>> = ffff83083d47f000 (XEN)     root_entry[8] = 72569b001 (XEN)
> >>>> context
> >>>> = ffff83072569b000 (XEN)     context[0] = 0_0 (XEN)
> >>>> ctxt_entry[0]
> >>>> not present
> >>>>
> >>>> So, capture card OK - Likely the Tundra bridge has an issue:
> >>>>
> >>>> 07:00.0 PCI bridge: Tundra Semiconductor Corp. Device 8113 (rev 01)
> >>>> (prog-if 01 [Subtractive decode])
> >>>>         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV-
> VGASnoop-
> >>>>         ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+
> >>>> 66MHz-
> >>>>         UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
> <MAbort+
> >>>>         >SERR- <PERR- INTx- Latency: 0 Bus: primary=07,
> >>>> secondary=08,
> >>>>         subordinate=08, sec-latency=32 Memory behind bridge:
> >>>>         f0600000-f06fffff Secondary status: 66MHz+ FastB2B+ ParErr-
> >>>>         DEVSEL=medium TAbort- <TAbort- <MAbort+ <SERR- <PERR-
> >>>> BridgeCtl:
> >>>>         Parity- SERR- NoISA- VGA- MAbort- >Reset- FastB2B-
> >>>>                 PriDiscTmr- SecDiscTmr- DiscTmrStat-
> DiscTmrSERREn-
> >>>>         Capabilities: [60] Subsystem: Super Micro Computer Inc
> >>>> Device 0805
> >>>>         Capabilities: [a0] Power Management version 3
> >>>>                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
> >>>>                 PME(D0+,D1+,D2+,D3hot+,D3cold+) Status: D0
> >>>> NoSoftRst+
> >>>>                 PME-Enable- DSel=0 DScale=0 PME-
> >>>>
> >>>> or there is some unknown bridge in the motherboard.
> >>>
> >>> According your description above, the upstream Linux should also have
> >>> the same problem. Did you see it with upstream Linux?
> >>
> >> The problem I was seeing with LSI cards (phantom device doing DMA)
> >> does, indeed, also occur in upstream Linux. If I enable intel-iommu on
> >> bare metal Linux, the same problem occurs as with Xen.
> >>
> >>> There may be some buggy device that generate DMA request with
> >>> internal
> >>> BDF but it didn't expose it(not like Phantom device). For those
> >>> devices, I think we need to setup the VT-d page table manually.
> >>
> >> I think what is needed is a pci-phantom style override that tells the
> >> hypervisor to tell the IOMMU to allow DMA traffic from a specific
> >> invisible device ID.
> >>
> >> Gordan
> >
> > There is.  See "pci-phantom" in
> > http://xenbits.xen.org/docs/unstable/misc/xen-command-line.html
> 
> I thought this was only applicable to phantom _functions_ (number after
> the
> dot) rather than whole phantom _devices_. Is that not the case?

I think that's right. I go through the related code for the pci phantom device 
just now, I find that
the information of command line 'pci-phantom' is stored in variable ' 
phantom_devs[8] '
with type of s truct phantom_dev{}. This variable is used in function 
alloc_pdev() as follow:


                for ( i = 0; i < nr_phantom_devs; ++i )
                    if ( phantom_devs[i].seg == pseg->nr &&
                         phantom_devs[i].bus == bus &&
                         phantom_devs[i].slot == PCI_SLOT(devfn) &&
                         phantom_devs[i].stride > PCI_FUNC(devfn) )
                    {
                        pdev->phantom_stride = phantom_devs[i].stride;
                        break;
                    }

So from the code, we can see this command line only works for phantom 
_function_, not for whole phantom _devices_.


> 
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Thanks,
Feng

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