[sparc64] [panic] cheetah_ipi_selected: CPU can't IPI itself

Well, I'm back in the same town as my sparc64 and so csup'd, built, and
rebooted, trying to get more information about the "vm object not owned"
panic I reported a while ago.  To my dismay, I now get this panic, also late
enough in the boot process to be starting up jails:

panic: cheetah_ipi_selected: CPU can't IPI itself
cpuid = 0
KDB: stack backtrace:
panic() at panic+0x1c8
cheetah_ipi_selected() at cheetah_ipi_selected+0x48
tlb_page_demap() at tlb_page_demap+0xdc
pmap_copy_page() at pmap_copy_page+0x4c4
vm_fault() at vm_fault+0x13ec
trap_pfault() at trap_pfault+0x190
trap() at trap+0xd0
-- data access protection tar=0x224b93 sfar=0x224550 sfsr=0x800005
%o7=0x4063398c --
userland() at 0x40633830
user trace: trap %o7=0x4063398c
...

And the system hangs; I had to use the ALOM to reboot it.
Sorry to not have more useful news.
--nwf;