Re: [Xen-devel] error when pass through device to guest with qemu-xen-dir-remote

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Anthony PERARD wrote on 2012-09-19:
> On Wed, Sep 19, 2012 at 1:06 AM, Zhang, Yang Z <yang.z.zhang@xxxxxxxxx>
> wrote:
>> Anthony PERARD wrote on 2012-09-18:
>>> 
>>> Hi,
>>> 
>>> So, we'll have to add a check in the unplug code of qemu to ignore
>>> passthrough devices.
>>> 
>>> Here is a patches, I did not test it.
>>> 
>>> diff --git a/hw/xen_platform.c b/hw/xen_platform.c
>>> index 0d6c2ff..2d3978e 100644
>>> --- a/hw/xen_platform.c
>>> +++ b/hw/xen_platform.c
>>> @@ -85,8 +85,10 @@ static void log_writeb ...
>>> 
>>>   static void unplug_nic(PCIBus *b, PCIDevice *d, void *o)
>>>   {
>>> +    /* We have to ignore passthrough devices */
>>>       if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
>>> -            PCI_CLASS_NETWORK_ETHERNET) {
>>> +            PCI_CLASS_NETWORK_ETHERNET
>>> +        && strcmp(d->name, "xen-pci-passthrough") != 0) {
>>>           qdev_free(&d->qdev);
>>>       }
>>>   }
>> 
>> In old qemu, we will free the invalid NIC through this function. And it will 
>> fail w/
> your change. Shouldn't we follow the old logic?
> 
> I don't understand. Are you arguing this patch or the function it self?
> 
> My change is fine and follow the old logic: do not do anything for a
> passthrough device.
No. Old logic will unplug the passthrough device which mask as invalid. And 
this patch just ignores all passthrough device.
I wonder whether this change will impact other part? If not, it should be ok.

> I now have tested the change, and QEMU work as espected, it will
> unplug the emulated NIC, and ignore any passthrough devices. So the
> guest can the passthroughed NIC.
> 
> Thanks,
> 
> --
> Anthony PERARD


Best regards,
Yang


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