Re: [PATCH V3 17/23] xen/ioreq: Introduce domain_has_ioreq_server()

[Oleksandr <olekstysh@gmail.com>]

On 08.12.20 17:11, Jan Beulich wrote:

Hi Jan

> On 30.11.2020 11:31, Oleksandr Tyshchenko wrote:
>> --- a/xen/include/xen/ioreq.h
>> +++ b/xen/include/xen/ioreq.h
>> @@ -55,6 +55,20 @@ struct ioreq_server {
>>       uint8_t                bufioreq_handling;
>>   };
>>   
>> +/*
>> + * This should only be used when d == current->domain and it's not paused,
> Is the "not paused" part really relevant here? Besides it being rare
> that the current domain would be paused (if so, it's in the process
> of having all its vCPU-s scheduled out), does this matter at all?do any extra actionsdo any extra actions

No, it isn't relevant, I will drop it.


>
> Apart from this the patch looks okay to me, but I'm not sure it
> addresses Paul's concerns. Iirc he had suggested to switch back to
> a list if doing a swipe over the entire array is too expensive in
> this specific case.
We would like to avoid to do any extra actions in 
leave_hypervisor_to_guest() if possible.
But not only there, the logic whether we check/set mapcache_invalidation 
variable could be avoided if a domain doesn't use IOREQ server...


-- 
Regards,

Oleksandr Tyshchenko