Panic on 11-STABLE with Xen guest

[John Baldwin]

On 11/22/18 12:39 PM, Joe Clarke wrote:
> I believe after the commit 340016 for the dynamic IRQ layout, my Xen VM
> started to panic.  I just upgraded the kernel today and saw this:
> 
> xen: unable to map IRQ#2
> panic: Unable to register interrupt override
> cpuid = 0
> KDB: stack backtrace:
> #0 0xffffffff8060a4e7 at kdb_backtrace+0x67
> #1 0xffffffff805c3787 at vpanic+0x177
> #2 0xffffffff805c3603 at panic+0x43
> #3 0xffffffff8093a766 at madt_parse_ints+0x96
> #4 0xffffffff803353f9 at acpi_walk_subtables+0x29
> #5 0xffffffff8093a5e6 at xenpv_register_pirqs+0x56
> #6 0xffffffff80928296 at intr_init_sources+0x116
> #7 0xffffffff8055eba8 at mi_startup+0x118
> #8 0xffffffff8029902c at btext+0x2c
> 
> The following kernel works:
> 
> @(#)FreeBSD 11.2-STABLE #4: Thu Nov  1 02:24:07 EDT 2018
> FreeBSD 11.2-STABLE #4: Thu Nov  1 02:24:07 EDT 2018
>     root at creme-brulee:/usr/obj/usr/src/sys/CREME-BRULEE
> 
> The following kernel produces the panic above immediately on boot:
> 
> @(#)FreeBSD 11.2-STABLE #5: Wed Nov 21 11:08:38 EST 2018
> FreeBSD 11.2-STABLE #5: Wed Nov 21 11:08:38 EST 2018
>     root at creme-brulee:/usr/obj/usr/src/sys/CREME-BRULEE
> 
> Attached is a screen grab of the console of the panic.

Hmm, I don't see any obvious candidates of Xen changes that weren't included
in the MFC.  I've added royger@ (who maintains Xen in FreeBSD) to the cc to
see if he has an idea.

Roger, the main changes that aren't MFC'd to 11 from 12/head seem to be some
refcounting on event channels and PVHv2 vs PVHv1?

-- 
John Baldwin