Xen MP hang in pmap

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hello,
since recent changes, Xen domUs with more than one vCPU hangs at boot
in pmap_update():
pmap_update(c0c751c0,c13e2000,c13e4000,c13e2000,2000,0,ccf7dd88,c041babf,c0c8d680,c13e2000) at netbsd:pmap_update+0x21
uvm_km_kmem_free(c0c8d680,c13e2000,2000,2,0,c13e3000,1,ccf7dd98,c03d267b,c13e2000) at netbsd:uvm_km_kmem_free+0x49
kmem_intr_free(c13e2000,2000,ccf7ddbc,c01359b0,c13e3000,c1428fcc,c0583f60,c13e3000,0,0) at netbsd:kmem_intr_free+0xaf
kern_free(c13e3000,c1428fcc,c0583f60,c13e3000,0,0,c1423008,ccf7de00,c013ac71,1) at netbsd:kern_free+0x2b
xenbus_printf(1,c1428fcc,c0583f60,c05b7843,1ff,c013b6f0,c1423008,0,c1331e64,28) at netbsd:xenbus_printf+0x70
xbd_xenbus_resume(c1331e48,c057371c,0,c1331e64,c0583f9a,c1331e48,c057d55f,c0b43a40,ccf7de54,c040b56c) at netbsd:xbd_xenbus_resume+0x251
xbd_xenbus_attach(c1331ac8,c1331e48,ccf7dee8,ccf7dee8,c0b439f8,c1331e48,ccf7dee8,c1331ac8,c0b439f8,ccf7de80) at netbsd:xbd_xenbus_attach+0x127
config_attach_loc(c1331ac8,c0b439f8,0,ccf7dee8,c0133ca0,c133a46c,c1428fcc,c1428f9c,0,ccf7dea0) at netbsd:config_attach_loc+0x19c
config_found_sm_loc(c1331ac8,c0582f59,0,ccf7dee8,c0133ca0,0,ccf7df00,c0134294,c1331ac8,c0582f59) at netbsd:config_found_sm_loc+0x5a
config_found_ia(c1331ac8,c0582f59,ccf7dee8,c0133ca0,a,0,c121e87c,0,c1232834,ccf7df2e) at netbsd:config_found_ia+0x32
xenbus_probe_device_type(ccf7df2e,1e,c05833be,c121e87c,ccf7df24,0,4,c121e86c,2,6 5640000) at netbsd:xenbus_probe_device_type+0x2f4
xenbus_probe_frontends(60,0,0,c01351b0,0,c058421b,0,0,ccf7df9c,c0134b6f) at netbsd:xenbus_probe_frontends+0xb8
xenbus_probe(0,c13433a0,c0134b20,0,0,c0102031,c13433a0,d6e000,c0b4f200,0) at netbsd:xenbus_probe+0x2e
xenbus_probe_init(c13433a0,d6e000,c0b4f200,0,c010007a,0,0,0,0,0) at netbsd:xenbus_probe_init+0x4f

pmap_update+0x21 is the call to pmap_tlb_shootnow() (which unfortunably
doesn't show up in the stack trace).

Any idea what can happen here ? At this point we're still in autoconf.
Interrupts are working but it's possible that CPUs are not fully up yet.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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