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

[Avi Kivity <avi@redhat.com>]

On 07/30/2012 05:07 PM, Chris Clayton wrote:
>>
>>>> With kernel 3.5.0 with b2da15ac26a0c00 reverted, I have just had 15
>>>> clean invocations of vanilla qemu-kvm-1.1.1. So that commit would seem
>>>> to be the problem.
>>>
>>> Just to be sure, I've run some more tests today. No crashes occurred in
>>> 20 runs of vanilla qemu-kvm-1.1.1 on kernel 3.5.0 with b2da15ac26a0c00
>>> reverted.
>>
>> Ok.  I'm trying to reproduce it here on a nested-virt setup, since the
>> code looks correct.
>>
>> What's your preemption settings?
>>
>>
> [chris:~/kernel/linux-3.5.0]$ grep PREEMPT .config
> CONFIG_TREE_PREEMPT_RCU=y
> CONFIG_PREEMPT_RCU=y
> CONFIG_PREEMPT_NOTIFIERS=y
> # CONFIG_PREEMPT_NONE is not set
> # CONFIG_PREEMPT_VOLUNTARY is not set
> CONFIG_PREEMPT=y
> CONFIG_PREEMPT_COUNT=y

Here's what I think that is happening

  vcpu_load
  ...
  vmx_save_host_state
  vmx_vcpu_run
  (ds.cpl, es.cpl cleared by hardware)

  interrupt
    push ds, es  # pushes bad ds, es
    schedule
      vmx_vcpu_put
        vmx_load_host_state
          reload ds, es
    pop ds, es  # of other thread's stack
    iret
  # other thread runs
  interrupt
    schedule  # back in vcpu thread
    interrupt return: pop ds, es  # <-- problem
    iret

   ...
   vcpu_put

   # bad ds, es, but !vmx->host_state.loaded

Marcelo, did I miss something here?

Unfortunately, my reproducer has ceased to reproduce.  But the fix is
easy if the analysis above is right.

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