Re: [Xen-users] PCI Passthrough, Radeon 7950 and Windows 7 64-bit

[Matthias <matthias.kannenberg@xxxxxxxxxxxxxx>]

Hi,

did some testing in my lunch break:

# dmesg -c && xm dmesg -c
# xm destroy WINDOMU
# dmesg
[257342.161103] xen1: port 1(work) entered disabled state
[257342.162777] xen1: port 1(work) entered disabled state
[257345.003372] irq 18: nobody cared (try booting with the "irqpoll" option)
[257345.004847] Pid: 11048, comm: qemu-dm Not tainted 3.4.2-xen #2
[257345.006208] Call Trace:
[257345.006208]  [<ffffffff800085d5>] dump_trace+0x85/0x1c0
[257345.006208]  [<ffffffff8088c036>] dump_stack+0x69/0x6f
[257345.006208]  [<ffffffff800c9936>] __report_bad_irq+0x36/0xe0
[257345.006208]  [<ffffffff800c9c8b>] note_interrupt+0x1fb/0x240
[257345.006208]  [<ffffffff800c72c4>] handle_irq_event_percpu+0x94/0x1d0
[257345.006208]  [<ffffffff800c7464>] handle_irq_event+0x64/0x90
[257345.006208]  [<ffffffff800ca7b4>] handle_fasteoi_irq+0x64/0x120
[257345.006208]  [<ffffffff80008468>] handle_irq+0x18/0x30
[257345.006208]  [<ffffffff805c1cc4>] evtchn_do_upcall+0x1c4/0x2e0
[257345.006208]  [<ffffffff808a308e>] do_hypervisor_callback+0x1e/0x30
[257345.006208]  [<ffffffff8014802a>] fget_light+0x3a/0xc0
[257345.006208]  [<ffffffff80159c65>] do_select+0x315/0x660
[257345.006208]  [<ffffffff8015a15a>] core_sys_select+0x1aa/0x2e0
[257345.006208]  [<ffffffff8015a347>] sys_select+0xb7/0x110
[257345.006208]  [<ffffffff808a29bb>] system_call_fastpath+0x1a/0x1f
[257345.006208]  [<00007f1a6d0081d3>] 0x7f1a6d0081d2
[257345.006208] handlers:
[257345.006208] [<ffffffff80658a80>] usb_hcd_irq
[257345.006208] [<ffffffff80658a80>] usb_hcd_irq
[257345.006208] [<ffffffff80658a80>] usb_hcd_irq
[257345.006208] Disabling IRQ #18
# xm dmesg
<nothing here>
# xm create WINDOMU
booted without problems and i played some Diablo 3 for testing
purpose: no performance change, everything normal

Then i analysed the kernel output in dmesg from the kill and found out
that the IRQ 18 is not in fact my graphic card what i always thought,
but my usb host controler which i have forwarded to the domU, too. So
appereantly there is no nothing vga related in the dmesg. Then I
thought okay, if the dom0 in fact doesn't care about the vga state, it
might actually be the domU and the only thing i guess can be
responsible for that is this in my domU config:

#######################
#   PCI Power Management:
#
#   If it's set, the guest OS will be able to program D0-D3hot states of the
# PCI device for the purpose of low power consumption.
#
pci_power_mgmt=1
#######################

My new theory is that this allowes the domU (and therefor my windows)
to reset the vga on boot so i don't have the problems you have..

Question is: Are you using this option in your domU or might that be
the difference in our configs?




2012/6/26 Radoslaw Szkodzinski <astralstorm@xxxxxxxxx>:
> On Tue, Jun 26, 2012 at 2:51 AM, Casey DeLorme <cdelorme@xxxxxxxxx> wrote:
>> I agree with you that Xen has an awareness, but what I read suggested that
>> the DomU is supposed to be responsible for the reset.
>
> Quite silly, many OSes and drivers don't care about device shutdown on
> "poweroff".
> Why should they, the power usually will be off real soon anyway.
> I think currently only Linux cares enough - due to the need to support kexec.
>
> Suspend to ram is different matter. Perhaps that avenue would be
> useful to explore.
> (Attempting to S2R the VM instead of shutdown...)
>
> Still, it'd be nice for Xen to force reset the devices (FLR, then
> D0->D3->D0 ASPM, then finally PCI bus reset as a last resort) when the
> VM stops using the devices.
> Better safe than sorry.
>
>> In any event, please
>> do post your results.  If you don't have the same performance degradation
>> and you can help identify where our configurations differ, it could help fix
>> the problem which would be awesome.
>
> --
> Radosław Szkodziński

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