Re: [RFC PATCH V1 08/12] xen/arm: Invalidate qemu mapcache on XENMEM_decrease_reservation

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.08.2020 13:35, Julien Grall wrote:
> On 05/08/2020 17:21, Jan Beulich wrote:
>> On 03.08.2020 20:21, Oleksandr Tyshchenko wrote:
>>> --- a/xen/common/memory.c
>>> +++ b/xen/common/memory.c
>>> @@ -1652,6 +1652,12 @@ long do_memory_op(unsigned long cmd, 
>>> XEN_GUEST_HANDLE_PARAM(void) arg)
>>>           break;
>>>       }
>>>   
>>> +    /* x86 already sets the flag in hvm_memory_op() */
>>> +#if defined(CONFIG_ARM64) && defined(CONFIG_IOREQ_SERVER)
>>> +    if ( op == XENMEM_decrease_reservation )
>>> +        curr_d->arch.hvm.qemu_mapcache_invalidate = true;
>>> +#endif
>>
>> Doesn't the comment already indicate a route towards an approach
>> not requiring to alter common code?
> 
> Given that IOREQ is now moved under common/, I think it would make sense 
> to have this set in common code as well for all the architecture.
> 
> IOW, I would suggest to drop the #ifdef CONFIG_ARM64. In addition, we 
> may want to introduce an helper to check if a domain is using ioreq.

Of course, with the (part of the) conditional dropped and the struct
field moved out of the arch sub-struct, this is fine to live here.

Jan