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Additional info(continued)
3. rhel6.8GA hit this regression issue, windows doesn't.
rhel6.8 GA doesn't work
windows 7 work
Comment 6Dr. David Alan Gilbert
2016-09-21 09:34:55 UTC
OK, I can reproduce this bug - only happens on my rhel/Xeon hosts, not on my fedora/laptop even with the same qemu.
Comment 7Dr. David Alan Gilbert
2016-09-21 12:38:54 UTC
If I add back the kvm_put_apic in kvm_arch_put_registers it seems to work again; so I'm guessing that means that something somewhere is changing the APIC state after the point we reset and before that point and we're losing the change.
Comment 8Dr. David Alan Gilbert
2016-09-21 17:51:01 UTC
Note if I turn on
apic=verbose debug ignore_loglevel
in the guest, I see it's stalled at 'calibrating APIC timer...'
If I make the code in kvm_arch_put_registers:
kvm_put_apic
like it was before it apparently works (not checked the migrate)
but if I make it:
kvm_get_apic
kvm_put_apic
it fails just like the put isn't there; so again it sounds like some inconsistent state that the put is restoring; so I do:
x86_cpu_dump_local_apic_state
kvm_get_apic
x86_cpu_dump_local_apic_state
kvm_put_apic
and expect to see the state that's different that's being lost without the put or with the get/put pair - nothing, no differences in the dump.
Hmm.
I add to the dump the dump of some other fields it hasn't got and the only ones that I've found different are initial_count_load_time and count_shift; however, if I preserve those around the get, it still fails - suggesting it's something else. Hmm.
Comment 9Dr. David Alan Gilbert
2016-09-22 12:13:18 UTC
Debugging with Paolo; this works with a host -490 kernel, breaks with a -491
==Verification(update)==
Results show:
Guest Basic(boot/reboot/shutdown) Migration
...
Windows10 PASS PASS
Note: In this testing, win10 migration works.
I will update this testing in bug[1].
[1]Bug 1357765 - windows10 guest hangs after migration
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHBA-2016-2673.html