Re: kvm problems with Intel host and netbsd/linux guests

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Jim Paris wrote:
> Hi,
>
> I'm having trouble getting kvm to work on my system.
> The host has 2 dual-core Intel Xeon 5130 CPUs (flags: lm vmx)
> and is running Linux 2.6.20.1 with kvm-15 (although I've had no luck
> with kvm-12 or kvm-14 either)
>
> If I take (for example) the NetBSD amd64 installation:
>
>   ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-3.1/amd64/installation/cdrom/amd64cd-3.1.iso
>
> and run it with
>
>   qemu-img create hda.img 4G
>   qemu-system-x86_64 -cdrom amd64cd-3.1.iso -hda hda.img -boot d
>
> then the screen flashes briefly but qemu crashes with
>
>   unhandled vm exit:  0x80000021
>   rax 0000000000000000 rbx 0000000000000000 rcx 0000000000000000 rdx 0000000000000600
>   rsi 0000000000000000 rdi 0000000000000000 rsp 0000000000000000 rbp 0000000000000000
>   r8  0000000000000000 r9  0000000000000000 r10 0000000000000000 r11 0000000000000000
>   r12 0000000000000000 r13 0000000000000000 r14 0000000000000000 r15 0000000000000000
>   rip 000000000000fff0 rflags 00023002
>   cs f000 (ffff0000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
>   ds 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
>   es 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
>   ss 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
>   fs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
>   gs 0000 (00000000/0000ffff p 1 dpl 3 db 0 s 1 type 3 l 0 g 0 avl 0)
>   tr 0000 (08850000/00002088 p 1 dpl 0 db 0 s 0 type b l 0 g 0 avl 0)
>   ldt 0000 (00000000/0000ffff p 1 dpl 0 db 0 s 0 type 0 l 0 g 0 avl 0)
>   gdt 0/ffff
>   idt 0/ffff
>   cr0 60000010 cr2 0 cr3 0 cr4 0 cr8 0 efer 0
>   Aborted
>
>   

It looks like the guest is rebooting (rip = 0xfff0), probably due to an 
earlier bug, so the register dump doesn't tell us much.


> If I try to run it without kvm:
>
>   qemu-system-x86_64 -no-kvm -cdrom amd64cd-3.1.iso -hda hda.img -boot d
>
> Then I get a blank SDL window that is entirely frozen (can't even
> switch to the qemu monitor).  If I use a stock qemu 0.8.2 to boot the
> cdrom and run the installer, then try to boot the resulting disk image
> with kvm:
>
>   qemu-system-x86_64 -hda hda.img -boot c
>   qemu-system-x86_64 -no-kvm -hda hda.img -boot c
>
> then I get the exact same results -- the first crashes with "unhandled
> vm exit" and the second freezes.
>
> Any suggestions?
>
> Also, on the Linux side of things, I have a disk image from a computer
> that also crashes when I try to boot it.  It dies with "exception 14"
> after Grub.  But, it does work fine with -no-kvm.  The kernel it's
> booting is a 32-bit k7 optimized kernel; is it expected behavior for
> that to work fine under -no-kvm but crash on an Intel host?
>   

If the kernel uses AMD-specific instructions, yes.  Can you send .config 
for that kernel?

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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