Re: [PATCH v2 2/7] xen/x86: merge 2 hvm_event_... functions into 1

[Corneliu ZUZU <czuzu@bitdefender.com>]

On 2/10/2016 6:18 PM, Jan Beulich wrote:
>>>> On 10.02.16 at 16:50, <czuzu@bitdefender.com> wrote:
>> @@ -151,61 +154,52 @@ void hvm_event_guest_request(void)
>>       }
>>   }
>>   
>> -int hvm_event_int3(unsigned long rip)
>> +static inline
>> +uint64_t gfn_of_rip(unsigned long rip)
> This should be a single line and the return value should be
> unsigned long.
Noted.
>> +    return (uint64_t) paging_gva_to_gfn(curr, sreg.base + rip, &pfec);
>>   }
> Pointless cast.
Noted.
>
>> --- a/xen/include/asm-x86/hvm/event.h
>> +++ b/xen/include/asm-x86/hvm/event.h
>> @@ -17,6 +17,12 @@
>>   #ifndef __ASM_X86_HVM_EVENT_H__
>>   #define __ASM_X86_HVM_EVENT_H__
>>   
>> +enum hvm_event_breakpoint_type
>> +{
>> +    HVM_EVENT_SOFTWARE_BREAKPOINT,
>> +    HVM_EVENT_SINGLESTEP_BREAKPOINT,
>> +};
> I don't see what good it does to put existing constants into an
> enum.
As Andrew pointed out, an enum was requested in v1 instead of the 
single_step param.
One could use the already existing VM_EVENT_REASON_* constants, but 
conceptually this
function only involves a subset of those (i.e. *breakpoint vm-events*).
>
>> @@ -27,9 +33,8 @@ bool_t hvm_event_cr(unsigned int index, unsigned long value,
>>   #define hvm_event_crX(what, new, old) \
>>       hvm_event_cr(VM_EVENT_X86_##what, new, old)
>>   void hvm_event_msr(unsigned int msr, uint64_t value);
>> -/* Called for current VCPU: returns -1 if no listener */
>> -int hvm_event_int3(unsigned long rip);
>> -int hvm_event_single_step(unsigned long rip);
>> +int hvm_event_breakpoint(unsigned long rip,
>> +                         enum hvm_event_breakpoint_type type);
> I guess the comment was here for a reason, and this reason doesn't
> go away with this code folding. But I'll leave it to the VM event code
> maintainers to judge.
>
> Jan
>
>
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>

That comment seemed & still seems wrong to me, I don't see any code 
paths out of which that function would return -1.

Thank you,
Corneliu.