Re: Status of pci passthrough work?

[Avi Kivity <avi@redhat.com>]

Jan C. Bernauer wrote:
> Hi,
>
>  I have about the same problem, so excuse me for hijacking this thread.
>
> My hardware consists of a 780g/SB700 Mainboard and a 4850e AMD CPU, and
> I'm interested in forwarding a DVB-C tuner card to the guest. Maybe
> some NICs later.
>
> I tried and 'sort of' got it working with Amit's kernel and userspace
> tools.
> First thing:
> The dvb-c card has an interesting memory mapping, as reported by
> lspci -v:
>         Memory at cfdff000 (32-bit, non-prefetchable) [size=512]
>
> Size 512 doesn't fly with a check in kvm_main.c:
> if (mem->memory_size & (PAGE_SIZE - 1))
>                 goto out;
>
> So I patched the userspace utilities to use 4096 instead.
>
> With that patch, the guest saw the card, the driver got loaded,
> and channel tuning works, but I get some i2c timeouts on the
> guest side, and the host side has errors like:
>
> ------------[ cut here ]------------
> Sep 22 02:28:54 [kernel] WARNING: at kernel/irq/manage.c:180
> enable_irq+0x3a/0x55()
> Sep 22 02:28:54 [kernel] Unbalanced enable for IRQ 20
>   

That looks due to bad error handling, due to the failures you had before.

Try rebooting the host and starting again with the patched userspace.

Amit, can you take a look at the error handling paths?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.