[Xen-users] PCI/USB forward to domU works, but this is a strange problem!

["Reinhard Proessler" <rpr-listen@xxxxxx>]

Hello

I'm fighting with a strange problem.
 
I've setup PCI to domU forwarding with the configuration/setup below. 
The problem:

If the USB device is unplugged and I start the the domU, the virtual machine 
comes up without problems.
The command lspci shows the controller:

00:00.0 USB Controller: Intel Corporation 82801CA/CAM USB Controller #1 (rev 02)

If I plug in the USB cable of the USB device it is found immediately, lsusb 
shows:

Bus 001 Device 002: ID 057c:2000 AVM GmbH ISDN-Connector FRITZ!X
Bus 001 Device 001: ID 0000:0000

This is what I expected. So far so good!

But if I shutdown the virtuell machine (domU) and leave the USB device plugged 
in,
then the virt. machine crashes on the next boot.

I can repeat it so often as I want:

unplugged device -> start of domU -> plug in the the device -> everything is 
fine.
device pluged in -> start of domU -> crash.

Well, i tried 'swiotlb=force', as suggestet in the crash message, but only then 
the crash message is only different. 

Can anybody enlighten me a little bit where the problem might be??

Kind Regards
RPr

----------------------------------------------------------------------------
My environment:
DELL 2600 with 
01:1d.0 PCI bridge: Intel Corporation 82870P2 P64H2 Hub PCI Bridge (rev 04)

OS RedHat EL 5.2
with kernel 2.6.18-92.1.10.el5xen, pciback as a module, pci frontend = Y

USB device is 
---
Bus 001 Device 002: ID 057c:2000 AVM GmbH ISDN-Connector FRITZ!X

in /etc/modprobe.conf
---
options pciback hide=(0000:00:1d.0)

in a script:
---
modprobe pciback
#
SLOT=0000:00:1d.0
# Unbind a PCI network card from its network driver
echo -n $SLOT > /sys/bus/pci/drivers/uhci_hcd/unbind
# And now bind it to the PCI Backend
echo -n $SLOT > /sys/bus/pci/drivers/pciback/new_slot
echo -n $SLOT > /sys/bus/pci/drivers/pciback/bind


in the domU configuration:
---
pci = [ '0000:00:1d.0' ]
usb = 1
usbdevice = [ 'host:057c:2000' ] 

and start the domU crashes immediately:

PCI: Fatal: No PCI config space access function found
rtc: IRQ 8 is not free.
i8042.c: No controller found.

Fatal DMA error! Please use 'swiotlb=force'
------------[ cut here ]------------
kernel BUG at arch/i386/kernel/pci-dma-xen.c:401!
invalid opcode: 0000 [#1]
SMP
last sysfs file: /block/ram0/dev
Modules linked in: dm_snapshot dm_zero dm_mirror dm_mod xenblk ext3 jbd 
uhci_hcd ohci_hcd ehci_hcd
CPU:    0
EIP:    0061:[<c040a39c>]    Not tainted VLI
EFLAGS: 00010292   (2.6.18-92.1.10.el5xen #1)
EIP is at dma_map_single+0x12d/0x147
eax: 0000002f   ebx: 00000000   ecx: 00000001   edx: f5416000
esi: 042a07e0   edi: 00000001   ebp: 00000008   esp: c0de1dbc
ds: 007b   es: 007b   ss: 0069
Process khubd (pid: 23, ti=c0de1000 task=c0dddaa0 task.ti=c0de1000)
Stack: c0622b1d c0da1c48 0082f7e0 00000000 c0da1c48 dff690c0 00000000 c0938c34
       c057c3c3 00000001 00000010 dfff9800 c057b122 00000000 dff690c0 00000000
       c057c387 c0de1f20 c0772f21 c0de1f20 ffffffff c04e3117 00000002 00000000
Call Trace:
 [<c057c3c3>] hcd_submit_urb+0x649/0x739
 [<c057b122>] usb_hcd_giveback_urb+0x28/0x53
 [<c057c387>] hcd_submit_urb+0x60d/0x739
 [<c04e3117>] vsnprintf+0x41f/0x45d
 [<c06094b8>] _spin_lock_irqsave+0x8/0x28
 [<c04219a2>] release_console_sem+0x18c/0x1c6
 [<c057c6c3>] usb_submit_urb+0x1b3/0x1d6
 [<c057cb49>] usb_start_wait_urb+0x39/0xd0
 [<c057cdc8>] usb_control_msg+0xc5/0xcf
 [<c057cdb8>] usb_control_msg+0xb5/0xcf
 [<c06f2800>] sanitize_e820_map+0x223/0x2b0
 [<c05789bb>] hub_port_init+0x1e4/0x46d
 [<c057a55d>] hub_thread+0x4f6/0x98d
 [<c06f2800>] sanitize_e820_map+0x223/0x2b0
 [<c060000a>] xfrm_add_policy+0xc7/0x153
 [<c06f2800>] sanitize_e820_map+0x223/0x2b0
 [<c043193f>] autoremove_wake_function+0x0/0x2d
 [<c057a067>] hub_thread+0x0/0x98d
 [<c043187d>] kthread+0xc0/0xeb
 [<c04317bd>] kthread+0x0/0xeb
 [<c0403005>] kernel_thread_helper+0x5/0xb
 =======================
Code: c0 74 07 8b 08 8b 58 04 eb 05 83 c9 ff 31 db 89 da 89 c8 f7 d2 f7 d0 21 
fa 21 f0 89 d1 09 c1 74 13 68 1d 2b 62 c0 e8 de 7b 01 00 <0f> 0b 91 01 fe 2a 62 
c0 5d f0 83 04 24 00 83 c4 0c 89 f0 89 fa
EIP: [<c040a39c>] dma_map_single+0x12d/0x147 SS:ESP 0069:c0de1dbc
 <0>Kernel panic - not syncing: Fatal exception

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