Re: [Xen-devel] [PATCH] xen: vmx: Use an INT 2 call to process real NMI's instead of self_nmi() in VMEXIT handler

[Keir Fraser <keir@xxxxxxx>]

On 13/11/2012 13:39, "Tim Deegan" <tim@xxxxxxx> wrote:

>>> diff -r 62885b3c34c8 -r e1fbee58b25c xen/arch/x86/hvm/vmx/vmx.c
>>> --- a/xen/arch/x86/hvm/vmx/vmx.c
>>> +++ b/xen/arch/x86/hvm/vmx/vmx.c
>>> @@ -2442,7 +2442,7 @@ void vmx_vmexit_handler(struct cpu_user_
>>>                   (X86_EVENTTYPE_NMI << 8) )
>>>                  goto exit_and_crash;
>>>              HVMTRACE_0D(NMI);
>>> -            self_nmi(); /* Real NMI, vector 2: normal processing. */
>>> +            asm("int $2"); /* Real NMI, vector 2: normal processing. */
>> 
>>                asm volatile("...")
>> 
>> I think? Otherwise this could potentially get hoisted up
> 
> Good catch.  Hoisted would be fine, but it could also be entirely
> discarded. :)

Parameter-less asm blocks are a special case that will never be considered
side-effect free I believe. Still 'asm volatile' would be our stylistic
choice in this case anyway.

And with that:
Acked-by: Keir Fraser <keir@xxxxxxx>



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