[Lguest] unhandled trap 13 on AMD X2

[Johannes Stezenbach]

Hi,

I'm currently running linux-2.6.30-rc7-149-g3218911 on an
AMD Athlon(tm) X2 Dual Core Processor BE-2400.

Lguest immediately dies with:

  # /lib/modules/2.6.30-rc7/build/Documentation/lguest/lguest 256 /lib/modules/2.6.30-rc7/build/vmlinux --tunnet=172.16.42.42 --block=lguest.img root=/dev/vda
  lguest: unhandled trap 13 at 0xc07d627a (0x0)

c07d625f <lguest_init>:
c07d625f:       55                      push   %ebp
c07d6260:       89 e5                   mov    %esp,%ebp
c07d6262:       53                      push   %ebx
c07d6263:       83 ec 14                sub    $0x14,%esp
c07d6266:       c7 05 8c 48 76 c0 a9    movl   $0xc069ada9,0xc076488c
c07d626d:       ad 69 c0 
c07d6270:       c7 05 88 48 76 c0 01    movl   $0x1,0xc0764888
c07d6277:       00 00 00 
c07d627a:       65 a1 14 00 00 00       mov    %gs:0x14,%eax
c07d6280:       89 45 f8                mov    %eax,-0x8(%ebp)
c07d6283:       31 c0                   xor    %eax,%eax
c07d6285:       c7 05 80 48 76 c0 01    movl   $0x1,0xc0764880
c07d628c:       00 00 00 
c07d628f:       c7 05 b8 48 76 c0 27    movl   $0xc07d6627,0xc07648b8
c07d6296:       66 7d c0 


The kvm_amd module loads at boot (I put it in
/etc/modprobe.d/blacklist.conf but it loaded anyway).
The error persists when I unload the kvm_amd + kvm modules.
(Incidentally kvm is also broken in that kernel
on my machine, but that shouldn't cause lguest problems, right?)

I have no clue about x86, but it seems the LHCALL_LGUEST_INIT
in lguest_entry fails to initialize (or clobbers) the %gs register?
Any idea how to debug or fix it?


Thanks,
Johannes