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

On 16/08/16 10:37, Alistair Popple wrote:

Balbir,

<snip>
 

quoted

quoted

+	/* 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.

quoted

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.