[Qemu-devel] [BUG 1.0] -cpu host breaks linux guest boot

[Luiz Capitulino]

Avi,

I'm getting the following panic very early on boot on a F16 VM (latest
qemu.git head 40897c9):

[    0.068018] Kernel panic - not syncing: Boot APIC ID in local APIC 
unexpected (-1 vs 0)
[    0.070006] Pid: 1, comm: swapper Not tainted 3.1.0-7.fc16.x86_64 #1
[    0.071004] Call Trace:
[    0.072035]  [<ffffffff814acb8e>] panic+0x91/0x1a5
[    0.073027]  [<ffffffff81b831ca>] native_smp_prepare_cpus+0x24c/0x300
[    0.075010]  [<ffffffff81b76c0d>] kernel_init+0x85/0x158
[    0.075993]  [<ffffffff810527eb>] ? schedule_tail+0x27/0x6c
[    0.076017]  [<ffffffff814be5f4>] kernel_thread_helper+0x4/0x10
[    0.077022]  [<ffffffff81b76b88>] ? start_kernel+0x3b6/0x3b6
[    0.078009]  [<ffffffff814be5f0>] ? gs_change+0x13/0x13

After some debugging and I found out that this only happens when '-cpu host'
is passed, and according to git bisect it's caused by the following commit:

commit 66e3dd9282141b5ae75637c9676002cf3ceeb988
Author: Avi Kivity <address@hidden>
Date:   Wed Nov 9 15:44:36 2011 +0200

    i386: derive '-cpu host' from KVM_GET_SUPPORTED_CPUID

Not sure if this is important, but here's procinfo information about
one of my host's cpus:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 23
model name      : Intel(R) Core(TM)2 Duo CPU     T9600  @ 2.80GHz
stepping        : 6
cpu MHz         : 2801.000
cache size      : 6144 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 2
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov 
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm 
constant_tsc arch_perfmon pebs bts rep_good aperfmperf pni dtes64 monitor 
ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 lahf_lm tpr_shadow vnmi 
flexpriority
bogomips        : 5585.87
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management: