RE: [Xen-devel] iommu: mapping reserved region failed - Q35 -VT-DIssue

["Ross Philipson" <Ross.Philipson@xxxxxxxxxx>]

The dump of the DMAR on your system showed the individual remapping
hardware units and which PCI devices they handled. Here is an excerpt
(my comment prefixed with a **):

DMA Remapping Hardware Unit Definition (DRHD) Structure #1
Type:           0x0000 (ACPI_DMAR_DRHD)
Length:         0x0018
Flags:          0x00  -- INCLUDE_ALL = no 
Reserved:       0x00
Segment Number: 0x0000
Register Base:  0xfed90000
    Device Scope Structure #1 ** This unit has one device scope entry
    ==========================
    Type:           0x01 (ACPI_DEV_ENDPOINT)
    Length:         0x08
    Reserved:       00 00
    Enumeration ID: 0x00 - Reserved
    Start Bus Num:  0x00
    Path Depth = 1, Path Entries:
       -- Device: 0x1b Function: 0x00 ** This unit support this
device/function on bus 0

DMA Remapping Hardware Unit Definition (DRHD) Structure #2
Type:           0x0000 (ACPI_DMAR_DRHD)
Length:         0x0028
Flags:          0x00  -- INCLUDE_ALL = no
Reserved:       0x00
Segment Number: 0x0000
Register Base:  0xfed92000
    Device Scope Structure #1 ** This unit has 3 device scope entries
each supporting one a different function on
device 3 bus 0
    ==========================
    Type:           0x01 (ACPI_DEV_ENDPOINT)
    Length:         0x08
    Reserved:       00 00
    Enumeration ID: 0x00 - Reserved
    Start Bus Num:  0x00
    Path Depth = 1, Path Entries:
       -- Device: 0x03 Function: 0x00 ** one function
    Device Scope Structure #2 ** another scope
    ==========================
    Type:           0x01 (ACPI_DEV_ENDPOINT)
    Length:         0x08
    Reserved:       00 00
    Enumeration ID: 0x00 - Reserved
    Start Bus Num:  0x00
    Path Depth = 1, Path Entries:
       -- Device: 0x03 Function: 0x02 ** another function
    Device Scope Structure #3 ** another scope
    ==========================
    Type:           0x01 (ACPI_DEV_ENDPOINT)
    Length:         0x08
    Reserved:       00 00
    Enumeration ID: 0x00 - Reserved
    Start Bus Num:  0x00
    Path Depth = 1, Path Entries:
       -- Device: 0x03 Function: 0x03 ** another function

Normally there is another DMA Remapping Hardware Unit Definition (DRHD)
that has the INCLUDE_ALL flag set and handles all devices that are not
specifically handled by DRHDs like the ones above (at least that has
been my experience though I haven't seen all that many machines). Your
system does not seem to have that. So there is no real way to setup DMA
remapping for any of the devices on your system that is not explicitly
represented above. My gut feeling is that it is a BIOS problem - the
ACPI tables are incorrect/incomplete but I cannot be sure.

If you use lspci you can see the (small) set of PCI devices that the
VT-d hardware seems to have DRHD units for. You might also want to
contact Lenovo and see if this is a known issue.

Thanks
Ross

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Stefan Bauer
Sent: Friday, October 31, 2008 3:43 PM
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] iommu: mapping reserved region failed - Q35
-VT-DIssue

Ross Philipson schrieb:
> That is a bummer. I am not really sure where to go with it. If there
is
> no DRHD for that device (or a number of other ones so it would seem)
> then there is no way to setup DMA remapping for those devices. Maybe
> someone else on the list has some ideas.

So if i understand you correctly, there is some problem with the PEG
graphic card in my case? Another graphic card might solve that problem?

Regards

-- 
stefan

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