Re: [Xen-devel] IOMMU fault with IGD passthrough setup on XEN 4.8.0

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.02.17 at 16:44, <firemeteor@xxxxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Feb 6, 2017 at 8:40 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>> On 05.02.17 at 06:51, <firemeteor@xxxxxxxxxxxxxxxxxxxxx> wrote:
>>> I finally get some spare time to collect the debug info.
>>
>> As I continue to be puzzled, best I could come up with is an
>> extension to the debug patch. Please use the attached one
>> in place of the earlier one, ideally on top of
>> https://lists.xenproject.org/archives/html/xen-devel/2017-02/msg00448.html 
>> to reduce the overall amount of output (and help readability).
> 
> Please see attached...

Thanks, this confirms my suspicion that EPT tables get updated, but
IOMMU ones don't. I'll have to go over the code yet another time to
see if I can spot what's wrong, or whether I need to further extend
the debugging patch.

Are you using a PVH Dom0 here, btw? If so, is the problem
connected to that? The fact that things work there may be
attributable to the mappings already being there even before the
identity mapping calls.

I further note that there's an apparently legitimate IOMMU fault
before the first guest gets started. This may indicate an issue
with the Dom0 kernel.

Jan


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