Re: [kvm-devel] bugreport: guest crashes on reboot in KVM 65 on AMD

[Avi K. <av...@qu...>]

Michal Ludvig wrote:
> Hi all,
>
> in short: CentOS 5 guest (32bit) crashes when I run "reboot" in the VM 
> with qemu message:
> kvm_run: failed entry, reason 65535
> kvm_run returned -8
>
> In dmesg is this message:
> kvm: 23769: cpu0 kvm_set_msr_common: MSR_IA32_MC0_STATUS 0x0, nop
>
> Details:
> KVM 65
> Host is openSUSE 10.3 with my own 2.6.24, 64 bit
> Guest is CentOS 5.1 with 2.6.18-53.1.14.el5, 32 bit
> GCC 4.2.1 for module, GCC 3.3.3 for qemu
> CPU "AMD Athlon(tm) 64 X2 Dual Core Processor 5600+"
>
> Everything works fine, except that I can't reboot the guest. In VNC it 
> says "md: stopping devices" and then Qemu exits with:
> kvm_run: failed entry, reason 65535
> kvm_run returned -8
>
> IIRC reboot used to work with kvm-64
>   

I think two bugs are involved:

- the guest invokes the triple-fault shutdown path, so it seems normal 
reboot doesn't work with iothread.  Haven't looked as to why yet.
- amd shutdown interception clears the vmcb, leaving asid == 0, which is 
illegal.  Adding force_new_asid() fixes this.  There are probably other 
issues with clearing the vmcb as well.

Joerg, can you find out if the "vmcb is undefined" applies to the entire 
vmcb or just the guest saved state?  Is there a way to differentiate 
between a guest initiated shutdown due to triple fault and the core 
melting down?

I'll commit the fix for the second problem, and look at the first later.

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