Re: [Bug 86951] New: iommu regression

[Bjorn Helgaas <bhelgaas@google.com>]

[+to linux-pci, +cc Alex]

On Sun, Oct 26, 2014 at 7:56 AM,  <bugzilla-daemon@bugzilla.kernel.org> wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=86951
>
>             Bug ID: 86951
>            Summary: iommu regression
>            Product: Drivers
>            Version: 2.5
>     Kernel Version: 3.13
>           Hardware: All
>                 OS: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: PCI
>           Assignee: drivers_pci@kernel-bugs.osdl.org
>           Reporter: nodenet@hotmail.com
>         Regression: No
>
> I am trying to make a Digium TDM410 PCI card available to a guest VM via VT-d /
> IOMMU. This appears to work under kernel 3.2 but not via any later kernel
> tested since.
>
> I noted pci_find_upstream_pcie_bridge errors
> (https://bugzilla.kernel.org/show_bug.cgi?id=44881) which appear resolved in
> 3.17 and above but was advised to file a new bug as this appears to be a new
> problem.
>
> Working kernel linux 3.2.0-70-generic
> Tested but not working 3.5.0-54-generic, 3.13.0-37-generic,
> 3.16.6-031606-generic, 3.17.1-031701-generic or 3.18.0-031800rc1-generic.
>
> 3.17.1 and 3.18.0-rc1 resolve the pci_find_upstream_pcie_bridge error message
> both still have the DMAR errors, the later has both read and write errors.
>
> https://bugs.launchpad.net/ubuntu/+source/linux-lts-trusty/+bug/1385388
>
> I believe this type of configuration is often achieved using Xen but I am using
> virtualbox 4.1.34 and it is possible there are some quirks associated with my
> motherboard.
>
> Motherboard: Gigabyte Technology Co., Ltd. Z87X-D3H/Z87X-D3H-CF, BIOS F9
> 08/25/2014 (latest)
>
> 03:00.0 Ethernet controller: Digium, Inc. Wildcard TDM410 4-port analog card
> (rev 11)
> 03:00.0 0200: d161:8005 (rev 11)
>
> 02:00.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 41) (prog-if 01
> [Subtractive decode])
> 02:00.0 0604: 8086:244e (rev 41)
>
> typical errors shown on the host when module loaded via modprobe in the
> guest....
>
> Oct 26 06:35:39 kernel: [ 227.795652] dmar: DRHD: handling fault status reg 3
> Oct 26 06:35:39 kernel: [ 227.795678] dmar: DMAR:[DMA Read] Request device
> [03:00.0] fault addr 73ac6000
> Oct 26 06:35:39 kernel: [ 227.795678] DMAR:[fault reason 06] PTE Read access is
> not set
>
> Modprobe freezes in the guest, guest is causing a high cpu load and freezes on
> reboot due to possible spin lock.
>
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