Re: [PATCH] powerpc/powernv: Initialise nest mmu

[Balbir Singh <bsingharora@gmail.com>]

On 16/08/16 10:37, Alistair Popple wrote:
> Balbir,
> 
> <snip>
>  
>>> +	/* Update partition table control register on all Nest MMUs */
>>> +	opal_nmmu_set_ptcr(-1UL, __pa(partition_tb) | (PATB_SIZE_SHIFT - 12));
>>> +
>>
>> Just wondering if
>>
>> 1. Instead of using -1 for all cpus, we should do
>> 	for_each_online_cpu() {
>> 		opal_numm_set_ptcr(...)
>> 	}
> 
> Good question, but I don't think it makes sense to do that. The NMMU is
> per-chip/socket rather than per-cpu so it shouldn't be tied to
> onlining/offlining of individual CPUs.
> 
>> 2. In cpu hotplug path do the same when onlining and set to NULL on
>> offlining?
> 
> Again, the nmmu isn't tied to a specific CPU but rather a chip/socket. So in
> theory at least it's possible that all CPUs in a chip could be offline but
> other units on the chip could still be using the nmmu so we wouldn't want to
> disable the nmmu at that point.

Fair enough

Balbir Singh.