Re: [Qemu-devel] Funny -m arguments can crash

[Markus Armbruster <armbru@redhat.com>]

Avi Kivity <avi@redhat.com> writes:

> On 08/14/2012 11:44 AM, Markus Armbruster wrote:
[...]
>> And another one:
>> 
>>     $ qemu-system-x86_64 -nodefaults --enable-kvm -vnc :0 -monitor
>> stdio -m 900k
>>     QEMU 1.1.50 monitor - type 'help' for more information
>>     (qemu) KVM internal error. Suberror: 1
>>     emulation failure
>>     EAX=000fdb78 EBX=00000000 ECX=00000000 EDX=000fdb64
>>     ESI=00000000 EDI=000fdb64 EBP=00000000 ESP=00006f98
>>     EIP=000e3492 EFL=00000006 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
>>     ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>>     CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
>>     SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>>     DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>>     FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>>     GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>>     LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
>>     TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
>>     GDT=     000fcd68 00000037
>>     IDT=     000fdb60 00000000
>>     CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
>>     DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000
>> DR3=0000000000000000
>>     DR6=00000000ffff0ff0 DR7=0000000000000400
>>     EFER=0000000000000000
>>     Code=00 00 b8 26 00 00 00 eb 95 83 c8 ff 83 c4 4c 5b 5e 5f 5d c3
>> <57> 56 53 89 d6 39 c2 72 06 89 c7 f3 a4 eb 1b 8d 51 ff 01 d0 01 d6
>> 89 cf 31 d2 eb 08 8a 1c
>>     q
>> 
>
> Not sure what's the problem.  57 is a push reg instruction which we
> ought to emulate fine.
>
> 900k is 0xe1000, just below eip, but we ought to execute just fine from
> unshadowed ROM.
>
>
>> Breakpoint on kvm_handle_internal_error() yields backtrace:
>> 
>>     #0  kvm_handle_internal_error (env=0x1389b30, run=0x7ffff7ffa000)
>>         at /work/armbru/qemu/kvm-all.c:1424
>>     #1  0x0000000000674c5a in kvm_cpu_exec (env=0x1389b30)
>>         at /work/armbru/qemu/kvm-all.c:1586
>>     #2  0x000000000060e0b4 in qemu_kvm_cpu_thread_fn (arg=0x1389b30)
>>         at /work/armbru/qemu/cpus.c:757
>>     #3  0x0000003b0ea07d14 in start_thread () from /lib64/libpthread.so.0
>>     #4  0x0000003b0def197d in clone () from /lib64/libc.so.6
>> 
>> Also seen with 904k, 908k, 964k, 968k, 972k 976k, and a whole lot more.
>
> Same EIP in the dump with those?

Offenders within 1s in range 868k..1028k step 4:

900
EIP=000e3492 EFL=00000006 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
904
EIP=000e3492 EFL=00000006 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
908
EIP=000e3492 EFL=00000006 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
916
EIP=000e570e EFL=00000012 [----A--] CPL=0 II=0 A20=1 SMM=0 HLT=0
964
EIP=000f2b76 EFL=00000012 [----A--] CPL=0 II=0 A20=1 SMM=0 HLT=0
968
EIP=000f2b76 EFL=00000012 [----A--] CPL=0 II=0 A20=1 SMM=0 HLT=0
972
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
976
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
980
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
984
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
988
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
992
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
996
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
1000
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
1004
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
1008
EIP=000fc6db EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
1012
EIP=000fe69f EFL=00000087 [--S--PC] CPL=0 II=0 A20=1 SMM=0 HLT=0
1016
EIP=000fe69f EFL=00000083 [--S---C] CPL=0 II=0 A20=1 SMM=0 HLT=0
1020
EIP=0000f000 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0

>> Not reproduced with 1024k+.
>> 
>> An easy way to "fix" these is to require 1MiB of RAM :)
>
> Or disabling kvm.