Re: [Xen-users] PCI Passthrough of iwlwifi adapter into Windows HVM failed to start

[John Mok <a9121431@xxxxxxxxx>]

>From what I understand, some devices can't be reinitialized (and won't work) 
>by the DomU driver after they've already been initialized on >the Dom0. 
>Blacklisting the module should prevent it from being initialized before being 
>passed through to the DomU.

The driver iwlwifi was compiled as a module and I can see it using
lsmod. The module has been preceeded by the xen-pciback, such that the
xen-pciback is loaded first, and I use the command, xl
pci-assignable-list, and the WiFi PCI device, i.e. 0030:00.0, appears.

>If that doesn't work, it's worth reading this page in full: 
>http://wiki.xenproject.org/wiki/Xen_PCI_Passthrough and mentioning your 
>distro, >Xen version, and hardware (e.g. whether you have an IOMMU or not).

In Xen 4.0.x, I succeeded to pass through LSI SAS controller to
Windows HVM. I had read through
http://wiki.xenproject.org/wiki/Xen_PCI_Passthrough, and the hardware
ThinkPad x250 has VT-d support in BIOS.

Any idea why the driver in Windows HVM could not start?

Thanks a lot.

John Mok


On Fri, Jan 1, 2016 at 9:36 PM,  <sm8ax1@xxxxxxxxxxx> wrote:
> Quoting "John Mok" <a9121431@xxxxxxxxx>:
>
>>> Just to confirm, are you certain that the driver in question really does
>>> work when it is running on baremetal ....?
>>
>>
>> Yes, the driver works on baremetal, but not try on other
>> virtualization passthrough.
>>
>>> I'm just guessing here, but does dmesg/journalctl have anything to say on
>>> the Dom0 side? In particular, an error about the driver >attempting to write
>>> to read-only configuration space could indicate that you need the
>>> "permissive=1" flag. See
>>> http://wiki.xenproject.org/wiki/Xen_PCI_Passthrough#PV_guests_and_PCI_quirks
>>
>>
>> I do not see anything complaining driver failing to write to read-only
>> configuration space. But somehow the Windows 7 HVM guest could not
>> bring up the Intel AC 7265 driver with error code 10 (fail to start).
>>
>> As the driver could run on baremetal, it should be a Xen PCI
>> passthrough problem.
>>
>> I hope someone could advise how to solve the problem, or point me to
>> the right direction.
>>
>> Thanks a lot.
>>
>> John Mok
>
>
> My mistake, the "permissive" flag only applies to PV guests.
>
> Once again I'm just guessing, but you could try blacklisting the module
> (iwlwifi) for the adapter on the Dom0. Make sure `lsmod | grep iwlwifi`
> outputs something, just to make sure that module isn't built into the
> kernel, then run `echo blacklist iwlwifi >> /etc/modprobe.d/blacklist` and
> reboot. Check your distro's documentation for blacklisting modules if that
> doesn't work.
>
> From what I understand, some devices can't be reinitialized (and won't work)
> by the DomU driver after they've already been initialized on the Dom0.
> Blacklisting the module should prevent it from being initialized before
> being passed through to the DomU.
>
> If that doesn't work, it's worth reading this page in full:
> http://wiki.xenproject.org/wiki/Xen_PCI_Passthrough and mentioning your
> distro, Xen version, and hardware (e.g. whether you have an IOMMU or not).
>
>
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