Re: IGD pass-through failures since 4.10.

["Dr. Greg" <greg@xxxxxxxxxxxx>]

On Mon, Feb 14, 2022 at 10:21:01AM +0100, Roger Pau Monn?? wrote:

Good afternoon, I hope the week has gone well for everyone.

> On Mon, Feb 14, 2022 at 12:00:11AM -0600, Dr. Greg wrote:

> >
> > [ Material removed ]
> >
> > It appears to be a problem with mapping interrupts back to dom0 given
> > that we see the following:
> > 
> > Feb 10 08:16:05 hostname kernel: xhci_hcd 0000:00:14.0: xen map irq failed 
> > -19 for 32752 domain
> > 
> > Feb 10 08:16:05 hostname kernel: i915 0000:00:02.0: xen map irq failed -19 
> > for 32752 domain
> > 
> > Feb 10 08:16:12 hostname kernel: xhci_hcd 0000:00:14.0: Error while 
> > assigning device slot ID

> Are you testing with an hypervisor with debug enabled? If not,
> please build one and see if there are any messages in Xen dmesg also
> as a result of the error (uisng `xl dmesg` if you don't have a
> serial attached to the box). Posting full Linux and Xen dmesgs (Xen
> build with debug=y) could also help.

It was just a stock build out of the GIT tree.

We will get a debug hypervisors built and get traces out of the test
machine and post them to this thread.  I don't believe that dom0
kernel was talking very much about what was going on but we will
verify that.

> PHYSDEVOP_map_pirq is failing but without further information it's
> impossible to limit the scope of the issue (and whether the issue is
> with PHYSDEVOP_map_pirq or some previous operation).

Very useful piece of information to have.

>From the log messages above, I assume the kernel is getting ENODEV
from the hypervisor call.  We will see if we can get some targeted
debug statements into the hypervisor to figure out what is going on.

> Thanks, Roger.

Thank you for the follow-up, have a good weekend.

Dr. Greg

As always,
Dr. Greg Wettstein, Ph.D    Worker / Principal Engineer
IDfusion, LLC
4206 19th Ave N.            Specialists in SGX secured infrastructure.
Fargo, ND  58102
PH: 701-281-1686            CELL: 701-361-2319
EMAIL: gw@xxxxxxxxxxxx
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