unhandled vm exit: 0x9

unhandled vm exit: 0x9

[Omar Khan]

hi, 
   I am trying to run an experimental operating system 'Choices' on kvm and it
is giving me the 'unhandled vm exit: 0x9' error. It runs fine with the -no-kvm
switch though. In an earlier post
(http://article.gmane.org/gmane.comp.emulators.kvm.devel/
654/match=unhandled+vm+exit) Avi said that "Exit 9 is a hardware task switch,
which is not supported by vmx" Can someone please elaborate on this. Also any
ideas on how to handle this?

Thanks 

Omar

unhandled vm exit:  0x9
rax 0000000000000000 rbx 0000000000032860 rcx 0000000000000090 
rdx 0000000000000000
rsi 0000000000000000 rdi 0000000000032928 rsp 0000000000277ff8 
rbp 0000000000000000
r8  b7f57ff40d7905c6 r9  b7f586f8080491f0 r10 b7f49ecdbfad98a0 
r11 b7ab33d0b7f588b8
r12 0000000100000001 r13 0804a1ef00000000 r14 0813e24400000000 
r15 09bb7cc0b7c7e651
rip 000000000010003c rflags 00000046
cs 0008 (00000000/00000000 p -1 dpl 1 db 0 s 1 type 1 l 11 g 0 avl 1)
ds 0010 (00000000/00000000 p -1 dpl 1 db 0 s 1 type 1 l 3 g 0 avl 1)
es 0000 (ffff0000/00000000 p -268431361 dpl 0 db 0 s 0 type 0 l 0 g 0 avl 0)
ss 0010 (00000000/00000000 p -1 dpl 1 db 0 s 1 type 1 l 3 g 0 avl 1)
fs 0000 (ffff0000/00000000 p -268431361 dpl 0 db 0 s 0 type 0 l 0 g 0 avl 0)
gs 0000 (ffff0000/00000000 p -268431361 dpl 0 db 0 s 0 type 0 l 0 g 0 avl 0)
tr 0000 (00000000/00000000 p 65535 dpl 1 db 0 s 0 type 0 l 11 g 0 avl 0)
ldt 0000 (ffff0000/00000000 p -268431361 dpl 0 db 0 s 0 type 0 l 0 g 0 avl 0)
gdt 100050/6f
idt 26ec20/7ff
cr0 60000011 cr2 0 cr3 0 cr4 0 cr8 0 efer 0
Aborted


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Re: unhandled vm exit: 0x9

[Avi Kivity]

Omar Khan wrote:
> hi, 
>    I am trying to run an experimental operating system 'Choices' on kvm and it
> is giving me the 'unhandled vm exit: 0x9' error. It runs fine with the -no-kvm
> switch though. In an earlier post
> (http://article.gmane.org/gmane.comp.emulators.kvm.devel/
> 654/match=unhandled+vm+exit) Avi said that "Exit 9 is a hardware task switch,
> which is not supported by vmx" Can someone please elaborate on this. Also any
> ideas on how to handle this?
>   

x86 supports a hardware task switch mechanism, almost an OS in 
hardware.  As no modern OS uses it, vmx (as well as svm and x86-64) does 
not support it.

There can be two causes for this:
- your OS actually uses the hardware task switch mechanism.  in this 
case, you need to emulate its behavior in kvm.
- some bug in kvm caused this to be triggered accidentally.

You can determine which case you're seeing by adding a printf() to the 
qemu task switch emulation and running with -no-kvm.  The place to put 
it is probably switch_tss() in target-i386/helper.c.

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


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