Re: [Xen-devel] [PATCH] amd iommu: Dump flags of IO page faults

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Fri, Sep 07, 2012 at 12:01:33PM +0200, Sander Eikelenboom wrote:
> 
> Friday, September 7, 2012, 10:54:40 AM, you wrote:
> 
> > On 09/07/2012 09:32 AM, Sander Eikelenboom wrote:
> >>
> >> Thursday, September 6, 2012, 5:03:05 PM, you wrote:
> >>
> >>> On 09/06/2012 03:50 PM, Sander Eikelenboom wrote:
> >>>>
> >>>> Thursday, September 6, 2012, 3:32:51 PM, you wrote:
> >>>>
> >>>>> On 09/06/2012 12:59 AM, Sander Eikelenboom wrote:
> >>>>>>
> >>>>>> Wednesday, September 5, 2012, 4:42:42 PM, you wrote:
> >>>>>>
> >>>>>>> Hi Jan,
> >>>>>>> Attached patch dumps io page fault flags. The flags show the reason of
> >>>>>>> the fault and tell us if this is an unmapped interrupt fault or a DMA 
> >>>>>>> fault.
> >>>>>>
> >>>>>>> Thanks,
> >>>>>>> Wei
> >>>>>>
> >>>>>>> signed-off-by: Wei Wang<wei.wang2@xxxxxxx>
> >>>>>>
> >>>>>>
> >>>>>> I have applied the patch and the flags seem to differ between the 
> >>>>>> faults:
> >>>>>>
> >>>>>> AMD-Vi: IO_PAGE_FAULT: domain = 0, device id = 0x0a06, fault address = 
> >>>>>> 0xc2c2c2c0, flags = 0x000
> >>>>>> (XEN) [2012-09-05 20:54:16] AMD-Vi: IO_PAGE_FAULT: domain = 0, device 
> >>>>>> id = 0x0a06, fault address = 0xc2c2c2c0, flags = 0x000
> >>>>>> (XEN) [2012-09-05 20:54:16] AMD-Vi: IO_PAGE_FAULT: domain = 14, device 
> >>>>>> id = 0x0700, fault address = 0xa8d339e0, flags = 0x020
> >>>>>> (XEN) [2012-09-05 20:54:16] AMD-Vi: IO_PAGE_FAULT: domain = 14, device 
> >>>>>> id = 0x0700, fault address = 0xa8d33a40, flags = 0x020
> >>>>
> >>>>> OK, so they are not interrupt requests. I guess further information from
> >>>>> your system would be helpful to debug this issue:
> >>>>> 1) xl info
> >>>>> 2) xl list
> >>>>> 3) lscpi -vvv (NOTE: not in dom0 but in your guest)
> >>>>> 4) cat /proc/iomem (in both dom0 and your hvm guest)
> >>>>
> >>>> dom14 is not a HVM guest,it's a PV guest.
> >>
> >>> Ah, I see. PV guest is quite different than hvm, it does use p2m tables
> >>> as io page tables. So no-sharept option does not work in this case. PV
> >>> guests always use separated io page tables. There might be some
> >>> incorrect mappings on the page tables. I will check this on my side.
> >>
> >> I have reverted the machine to xen-4.1.4-pre (changeset 23353) and kept 
> >> everything else the same.
> >> I haven't seen any IO PAGE FAULTS after that.
> >>
> >> I did spot some differences in the output from lspci between xen 4.1 and 
> >> 4.2, related to MSI enabled or not for the IOMMU device.
> >> Have attached the xl/xm dmesg and lspci from booting with both versions.
> >>
> >> lspci:
> >>
> >> 00:00.2 Generic system peripheral [0806]: ATI Technologies Inc RD990 I/O 
> >> Memory Management Unit (IOMMU) [1002:5a23]
> >>          Subsystem: ATI Technologies Inc RD990 I/O Memory Management Unit 
> >> (IOMMU) [1002:5a23]
> >>          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
> >>          Interrupt: pin A routed to IRQ 10
> >>          Capabilities: [40] Secure device<?>
> >> 4.1:    Capabilities: [54] MSI: Enable- Count=1/1 Maskable- 64bit+
> 
> > Eh... That is interesting. So which dom0 are you using?  There is a c/s 
> > in 4.2 to prevent recent dom0 to disable iommu interrupt (changeset 
> > 25492:61844569a432) Otherwise, iommu cannot send any events including IO 
> > PAGE faults. You could try to revert dom0 to an old version like 2.6 
> > pv_ops to see if you really have no io page faults on 4.1
> 
> Ok i will give that a try, only dom0 will have to be a 2.6 pv_ops i assume ?
> 

So the failure they are describing is due to:
http://lists.xen.org/archives/html/xen-devel/2012-06/msg00668.html

Or you can use the patch that Jan posted
http://lists.xen.org/archives/html/xen-devel/2012-06/msg01196.html

and use the existing kernel.. But more interesting - is this device
(00:00.2) in the Xen-pciback.hide arguments (if not, then don't worry)?

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