KVM PCI passthrough issues, RTL-8169 PCI NICs

[Andrew Useckas <dronin@gmail.com>]

Hi,

I have been trying to get the PCI pass through working on my Asus Crosshair IV 
Formula motherboard.

The motherboard does support IOMMU (AMD-Vi), and IOMMU as well as SVM are 
enabled in the BIOS.

PCI pass through does seem to work just fine when it comes to with built in 
network device (Marvel 8059 Yukon), however I can't get it working with two 
PCI RTL-8169 network cards. Both devices are bound to pci-stub.

Every time I attempt I get a message that the device is busy, as shown below:

PCI region 1 at address 0xf9dff800 has size 0x100, which is not a multiple of 
4K. You might experience some performance hit due to that.
Failed to assign device "(null)" : Device or resource busy
*** The driver 'pci-stub' is occupying your device 0000:01:05.0.


The kernel logs show the following:

Dec 14 10:19:55 phalsenet kernel: [ 1718.806644] pci-stub 0000:01:05.0: PCI 
INT A -> GSI 20 (level, low) -> IRQ 20
Dec 14 10:19:55 phalsenet kernel: [ 1718.836741] pci-stub 0000:01:05.0: 
restoring config space at offset 0x1 (was 0x2b00400, writing 0x2b00103)
Dec 14 10:19:55 phalsenet kernel: [ 1718.903118] assign device 0:1:5.0 failed
Dec 14 10:19:55 phalsenet kernel: [ 1718.903161] pci-stub 0000:01:05.0: PCI 
INT A disabled


The box is running Gentoo Linux. I have tested with 2.6.34 and 2.6.36 kernels, 
with kvm and kvm-amd modules that came with the kernels as well as with the 
latest kvm-kmod sources (2.6.36.1).

The qemu-kvm version is 0.13.0.

Here lspci -v output from one of the network devices:

01:05.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit 
Ethernet (rev 10)
        Subsystem: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet
        Flags: 66MHz, medium devsel, IRQ 20
        I/O ports at b400 [size=256]
        Memory at f9dff800 (32-bit, non-prefetchable) [size=256]
        Expansion ROM at f9da0000 [disabled] [size=128K]
        Capabilities: [dc] Power Management version 2
        Kernel driver in use: pci-stub


Any help would be appreciated.

Regards,
Andrew