Guest hang after live migration

[chao zhou]

Environment:
------------
Host OS (ia32/ia32e/IA64):ia32e
Guest OS (ia32/ia32e/IA64):ia32e
Guest OS Type (Linux/Windows):Linux
kvm.git Commit:205befd9a5c701b56f569434045821f413f08f6d
qemu-kvm uq/master Commit:ca916d3729564d0eb3c2374a96903f7e8aced8a7
Host Kernel Version:3.11.0-rc1
Hardware:Romley_EP, Ivytown_EP

Bug detailed description:
--------------------------
after guest live migration, the guest will hang, and ping IP fail

note:
1. after guest save/restore, the guest will hang, and ping IP fail
2. This should be a qemu-kvm bug.
kvm + qemu-kvm = result
205befd9 + ca916d37 = bad
205befd9 + f03d07d4 = good

Reproduce steps:
----------------
1.Start a TCP daemon for migration
qemu-system-x86_64 -enable-kvm -m 2G -smp 2 -net nic,macaddr=00:12:34:56:13:45
-net tap,script=/etc/kvm/qemu-ifup rhel6u2.qcow -incoming tcp:localhost:4444
2. create guest
qemu-system-x86_64 -enable-kvm -m 2G -smp 2 -net nic,macaddr=00:12:34:56:13:45
-net tap,script=/etc/kvm/qemu-ifup rhel6u2.qcow
3. migrate tcp:localhost:4444

Current result:
----------------
guest hang

Expected result:
----------------
after live/migration or save/restore, the guest works fine

[Lei Li (matrixs-zero)]

Hi,

qemu-kvm no longer exists as it has been merged into qemu.
You might want to have a try with the lastest upstream/master qemu tree, or pre-release versions of it. :)

[chao zhou (chao-zhou)]

Jinsong Liu (@Intel) 's patch "qemu-kvm bugfix for IA32_FEATURE_CONTROL" will fix this bug.
That patch will also fix the following bug.
 10. 64bit RHEL6.4 guest crashes and reboots continuously
  https://bugs.launchpad.net/qemu-kvm/+bug/1207623

So you suggent we should use qemu instead of qemu-kvm, right?

Thanks.

[Lei Li (matrixs-zero)]

Hi,

Yes, qemu-kvm is no longer maintained since 1.3, it'd be better to switch to qemu if you want an active one.
This patch will be applying to up/master in QEMU branch as well.

[chao zhou (chao-zhou)]

OK. Thanks.

[chao zhou (chao-zhou)]

The bug has been fixed by the following commit:

commit df67696e97d3edd0cb1683bf2eb3b3236bd9a5ed
Author: Liu Jinsong <email address hidden>
Date: Mon Aug 19 09:33:30 2013 +0800

    kvm: x86: fix setting IA32_FEATURE_CONTROL with nested VMX disabled

    This patch is to fix the bug https://bugs.launchpad.net/qemu-kvm/+bug/120762

    IA32_FEATURE_CONTROL is pointless if not expose VMX or SMX bits to
    cpuid.1.ecx of vcpu. Current qemu-kvm will error return when kvm_put_msrs
    or kvm_get_msrs.

    Signed-off-by: Liu Jinsong <email address hidden>
    Signed-off-by: Paolo Bonzini <email address hidden>

[Paolo Bonzini (bonzini)]

The fix is in no released version, so the bug is stomped.