NetBSD dom0 PVH: hardware interrupts stalls

[Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>]

Hello,
so, after fixing an issue in the NetBSD kernel, related to PV clock
interrupts, I'm back with physical interrupts issues.
At some point in the initialisation, the dom0 kernel stops receiving
interrupts for its disks controller. The disk controller is:
[   1.0000030] mfii0 at pci6 dev 0 function 0: "PERC H740P Adapter ", firmware 
51.13.0-3485, 8192MB cache
(XEN) d0: bind: m_gsi=34 g_gsi=34
[   1.0000030] allocated pic ioapic2 type level pin 2 level 6 to cpu0 slot 2 
idt entry 103
[   1.0000030] mfii0: interrupting at ioapic2 pin 2

entering the NetBSD kenrel debugger and looking at interrupt counters,
I see that some interrupts did trigger on ioapic2 pin 2, as well as for
some other hardware controllers.
I did print the controller's status when the command times out, and
the controller says that there is an interrupt pending. So I guess that
the command was executed, but the dom0 kernel didn't get interupted.

At this point I can't say if other hardware controller interripts are
working (because of the lockdown I don't have physical access
to the hardware).

What's strange is that some Xen console activity seems to be enough to
resume interrupt activity. Hitting ^A 3 times is enough to get some progess
on the dom0's disk controller, and hitting 'v' is usually enough to
get the dom0 multiuser. Once there the systems looks stable, I can log
in from network. But I/O may stall again on reboot, maybe because the
dom0 kenrel is back using synchronous console output.

Any idea what to look at from here ?

-- 
Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>
     NetBSD: 26 ans d'experience feront toujours la difference
--