Re: [Xen-devel] [PATCH v7] x86/emulate: Send vm_event from emulate

[Alexandru Stefan ISAILA <aisaila@bitdefender.com>]

On 12.07.2019 04:28, Jan Beulich wrote:
> On 11.07.2019 19:13, Tamas K Lengyel wrote:
>>> @@ -629,6 +697,14 @@ static void *hvmemul_map_linear_addr(
>>>
>>>                ASSERT(p2mt == p2m_ram_logdirty || !p2m_is_readonly(p2mt));
>>>            }
>>> +
>>> +        if ( curr->arch.vm_event &&
>>> +            curr->arch.vm_event->send_event &&
>>
>> Why not fold these checks into hvm_emulate_send_vm_event since..
> 
> I had asked for at least the first of the checks to be pulled
> out of the function, for the common case to be affected as
> little as possible.
> 
>>> --- a/xen/arch/x86/hvm/hvm.c
>>> +++ b/xen/arch/x86/hvm/hvm.c
>>> @@ -3224,6 +3224,14 @@ static enum hvm_translation_result __hvm_copy(
>>>                return HVMTRANS_bad_gfn_to_mfn;
>>>            }
>>>
>>> +        if ( unlikely(v->arch.vm_event) &&
>>> +            v->arch.vm_event->send_event &&
>>
>> .. you seem to just repeat them here again?
> 
> I agree that the duplication makes no sense.
> 

The first check is on the hvmemul_map_linear_addr() path and the second 
is on hvmemul_insn_fetch() path. There are 2 distinct ways to reach that 
if and therefore the check is not duplicated.

Thanks,
Alex
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