[vfio-users] Lost link when pass through rtl8168 to guest

[Wei Xu]

On 2016年09月21日 12:31, Alex Williamson wrote:
> On Wed, 21 Sep 2016 11:52:31 +0800
> Wei Xu <wexu at redhat.com> wrote:
>
>> On 2016年09月21日 02:59, Nick Sarnie wrote:
>>> Hi Wei,
>>>
>>> My system is a desktop, so it must just be a general Gigabyte BIOS bug.
>>> I submitted a help ticket about this issue and just gave a brief
>>> explanation and then sent Alex's explanation. Hopefully it will be
>>> escalated correctly.
>>
>> Thanks for your feedback, i'm also using a Gigabyte board, i have
>> checked out the firmware update history and updated my firmware to the
>> latest one which was released at March, looks it's a long way to get a
>> feedback for this issue from them.
>>
>> Alex,
>> It's a hard time for us to do nothing but wait, the reason why i use my
>> desktop is i got a com console on it, so it's quite convenient to
>> debugging kernel via kgdb, and i want to keep my realtek nic for ssh
>> access from my notebook, anyway to workaround it to just bypass the
>> wireless nic only as a temporary experiment?
>>
>> I'm trying VirtIO DMAR patch with vIOMMU in the guest recently, which
>> need pass through a pcie unit from host, and one more virtio nic for the
>> guest due to the feedbacks, maybe i can pass through a device in other
>> groups instead of a nic?
>
> Sure, but skylake platforms are notoriously bad for their lack of
> device isolation, even things like USB controllers and audio devices
> are now part of multifunction packages that do not expose isolation
> through ACS.  If you can't resolve the IOMMU grouping otherwise, your
> choices are as I told Nick in the other thread:
>
>    "Your choices are to run an unsupported (and unsupportable)
>    configuration using the ACS override patch, get your hardware vendor
>    to fix their platform, or upgrade to better hardware with better
>    isolation characteristics."
>
> It's unfortunate that Intel provides VT-d on consumer platforms without
> sufficient device isolation to really make it usable, but that's often
> the state of things.  The workstation and server class platforms,
> supporting Xeon E5 or High End Desktop Processors provide the necessary
> isolation.  Thanks,

Yes, fortunately i get it solved finally, i tried adding the 'r8169' 
driver to the kernel group whitelist behind 'pci-stub' and recompile  & 
update the kernel firstly, and the VM boot up successfully, but a map 
page to iova error for realtek nic during DMA crashed the system later, 
looks it was caused by the group dependency, i remembered the vfio doc 
tells the group is the minimum isolation unit.

Then i found there are 3 pci bridges on my board, 2 of them are with a 
group, another is a separate group, after plug the iwl wlan nic to this 
one, everything works well.

Wei


>
> Alex
>