Re: qemu-kvm-1.1.0 crashing with kernel 3.5.0-rc6

[Avi Kivity <avi@redhat.com>]

On 07/27/2012 10:04 PM, Chris Clayton wrote:
> On 07/27/12 19:08, Eric Northup wrote:
>> Could you include the output of "info registers" at the point where it
>> crashed?
>>
> 
> Here you go:
> 
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0xb6a78b40 (LWP 13249)]
> __strcmp_sse4_2 () at ../sysdeps/i386/i686/multiarch/strcmp-sse4.S:217
> 217             movdqu  (%edx), %xmm2
> (gdb) bt
> #0  __strcmp_sse4_2 () at ../sysdeps/i386/i686/multiarch/strcmp-sse4.S:217
> #1  0xb7e82cb4 in g_str_equal (v1=0x8a0cd58, v2=0x8319b82) at ghash.c:1704
> #2  0xb7e8137a in g_hash_table_lookup_node (hash_table=0x89fe800,
> key=0x8319b82, hash_return=0xb6a78178)
>     at ghash.c:422
> #3  0xb7e821e5 in g_hash_table_lookup (hash_table=0x89fe800,
> key=key@entry=0x8319b82) at ghash.c:1074
> #4  0x0815c9cb in type_table_lookup (name=0x8319b82 "apic-common") at
> qom/object.c:94
> #5  type_get_by_name (name=name@entry=0x8319b82 "apic-common") at
> qom/object.c:149
> #6  0x0815cf93 in object_dynamic_cast (obj=obj@entry=0x8a313e0,
> typename=typename@entry=0x8319b82 "apic-common")
>     at qom/object.c:416
> #7  0x0815cf2d in object_dynamic_cast_assert (obj=obj@entry=0x8a313e0,
>     typename=typename@entry=0x8319b82 "apic-common") at qom/object.c:478
> #8  0x08192c1b in cpu_set_apic_tpr (d=0x8a313e0, val=13 '\r')
>     at /home/chris/rpm/BUILD/qemu-kvm-1.1.1/hw/apic_common.c:60
> #9  0x081cb86c in kvm_arch_post_run (env=env@entry=0x8a29370,
> run=run@entry=0xb6274000)
>     at /home/chris/rpm/BUILD/qemu-kvm-1.1.1/target-i386/kvm.c:1695
> #10 0x081c686f in kvm_cpu_exec (env=env@entry=0x8a29370) at
> /home/chris/rpm/BUILD/qemu-kvm-1.1.1/kvm-all.c:1269
> #11 0x08198c72 in qemu_kvm_cpu_thread_fn (arg=0x8a29370) at
> /home/chris/rpm/BUILD/qemu-kvm-1.1.1/cpus.c:752
> #12 0xb7a3ed9e in start_thread () from /lib/libpthread.so.0
> #13 0xb77e45ee in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:132
> (gdb) info registers
> eax            0x8319b82        137468802
> ecx            0xd58    3416
> edx            0x8a0cd58        144756056
> ebx            0xb7f7f2c4       -1208487228
> esp            0xb6a780ec       0xb6a780ec
> ebp            0xb6a78118       0xb6a78118
> esi            0x8a313e0        144905184
> edi            0xc513   50451
> eip            0xb7824f77       0xb7824f77 <__strcmp_sse4_2+23>
> eflags         0x10283  [ CF SF IF RF ]
> cs             0x73     115
> ss             0x7b     123
> ds             0x0      0
> es             0x0      0
> fs             0x0      0
> gs             0x33     51
> 

ds shouldn't be zero for a 32-bit process.

But that should have crashed *much* earlier, ds is accessed all the time.

Please add the following snippet to the beginning of kvm_arch_post_run():

{
    unsigned short ds;
    asm("mov %%ds, %0" : "=rm"(ds));
    assert(ds != 0);
}

if the assert triggers, then kvm corrupted the segment registers.  If
not, corruption happens somewhere above.

-- 
error compiling committee.c: too many arguments to function