Re: bugreport: guest crashes on reboot in KVM 65 on AMD

[Avi Kivity <avi@qumranet.com>]

Joerg Roedel wrote:
> On Mon, Apr 14, 2008 at 12:43:30PM +0300, Avi Kivity wrote:
>   
>> 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?
>>     
>
> Only the state saved in the VMCB is undefined after an intercepted
> shutdown event. 

The vmcb stores two types of states, guest state and control 
information.  Are both undefined?

> I am not sure if I understand your second question, what
> do you mean with "core melting down" vs. guest initiated shutdown?
>   

IIRC shutdown can occur not only as a result of triple faults, due to 
other internal errors or inconsistent state.  Not sure about that though.


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


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