Re: AMD iommu , pci passthrough problems assigning devices to HVM

[Wei Wang2 <wei.wang2@amd.com>]

Hi,
In your debug output I saw:
(XEN) AMD-Vi: Fail to find iommu for device04:00.0
This means no iommu attached to 04:00.0, so it cannot be assigned to any hvm 
guest. What is this device in your system? An add-on device or on board 
device? It looks like BIOS failed to create an IVRS entry for this device.

Wei

On Tuesday 10 August 2010 14:26:14 Sander Eikelenboom wrote:
> Hi,
>
> I'm running a machine with:
> - Hypervisor: xen-unstable
> - Dom0: xen/next-2.6.32.17  commit c3f5aba942c7516a5c76c47345ff0a473daf2542
>
> Hardware:
> -MSI 890FXA-GD70 with AMD IOMMU
> -Phenom X6
>
> I'm trying to do PCI passthrough to a HVM, this fails with:
>
> Error: Failed to assign device to IOMMU
> (0000:04:00.0@100,msitranslate=1,power_mgmt=0) Error: pci: to avoid
> potential security issue, 0000:08:00.0 is not allowed to be assigned to
> guest since it is behind PCIe switch that does not support or enable ACS.
>
>
> I have found this thread https://bugzilla.redhat.com/show_bug.cgi?id=526713
> regarding the ACS problem, which says the pci bridges need these
> capabilities: ScrValid+, ReqRedir+, CmpltRedir+, and UpstreamFwd+
>
> When i do a lspci -vvv on my system i see these capabilities, but i do see
> some disturbing debug message on boot when amd_iommu_debug is on.
>
> Attached:
> - xm info
> - xm dmesg (booted with amd_iommu_debug on)
> - dmesg
> - lspci -vvv
>
> --
> Sander