64bit RHEL6.4 guest crashes and reboots continuously

[Yongjie Ren]

Environment:
------------
Host OS (ia32/ia32e/IA64):ia32e
Guest OS (ia32/ia32e/IA64):ia32e
Guest OS Type (Linux/Windows):Linux
kvm.git next Commit:9576c4cd6b6fa5716400e63618757b76cff6a813
qemu-kvm uq/master Commit:0779caeb1a17f4d3ed14e2925b36ba09b084fb7b
Host Kernel Version:3.11.0-rc1
Hardware: SandyBridge-EP

Bug detailed description:
--------------------------
RHEL6.4 guest alwasy crashes and reboots. 32bit RHEL6.4 and 64bit RHEL6.3 guest can work fine.

kvm next + qemu-kvm uq/master = result
9576c4cd + 0779caeb = bad
9576c4cd + c3cb8e77 = good

seems the following commit is the culprit commit.

commit 0779caeb1a17f4d3ed14e2925b36ba09b084fb7b
Author: Arthur Chunqi Li <email address hidden>
Date: Sun Jul 7 23:13:37 2013 +0800

    Initialize IA32_FEATURE_CONTROL MSR in reset and migration

    The recent KVM patch adds IA32_FEATURE_CONTROL support. QEMU needs
    to clear this MSR when reset vCPU and keep the value of it when
    migration. This patch add this feature.

Reproduce steps:
----------------
1. qemu-system-x86_64 -enable-kvm -m 1024 -smp 2 -net none /root/rhel6u4.qcow

Current result:
----------------
guest reboot continuously

Expected result:
----------------
guest boot up fine

Basic root-causing log:
----------------------
(guest serial port log is attached.)

[chao zhou (chao-zhou)]

This commit fix this bug:
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>