RE: [Xen-devel] [PATCH] X86 MCE: Add SRAR handler

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.09.11 at 10:21, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
> Jan Beulich wrote:
>>>>> On 30.09.11 at 09:44, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
>>> Jan Beulich wrote:
>>>>>>> On 30.09.11 at 04:51, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>
>>>>>>> wrote:
>>>>>> This made me look at the current source, and there I see in
>>>>>> mce_urgent_action() 
>>>>>> 
>>>>>>     if ( !(gstatus & MCG_STATUS_RIPV) && !guest_mode(regs))
>>>>>> return -1; 
>>>>>> 
>>>>>> which I think should say ... _EIPV and use || instead. Thoughts?
>>>>> 
>>>>> I think this code means, if the error happens in hypervisor mode
>>>>> (i.e. !guest_mode()), and RIPV indicate the RIP in stack can't be
>>>>> restarted, we have to panic.
>>>> 
>>>> Then the guest_mode() check still lacks an extra check of EIPV, like
>>>> 
>>>>      if ( !(gstatus & MCG_STATUS_RIPV) &&
>>>>           (!(gstatus & MCG_STATUS_EIPV) || !guest_mode(regs)))     
>>>> return -1; 
>>>> 
>>> 
>>> That would be overkilled.
>>> Considering instruction fetch error occur at guest context,
>>> hypervisor deliver to guest to handle the error is perfer, not panic
>>> all system. 
>> 
>> Even if it was hypervisor code that got prefetched while still
>> executing guest code (which ought to be possible at least
>> across a syscall/sysenter instruction)?
>> 
> 
> Executing guest code will not satisfy the check
> if ( !(gstatus & MCG_STATUS_RIPV) && !guest_mode(regs))
>       return -1;
> so it would not panic system.

Exactly. But it should when the prefetch was to hypervisor code.

Jan


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