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
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