Re: [PATCH 4/5] powernv:idle: Move initialization of sibling pacas to pnv_alloc_idle_core_states

From: Nicholas Piggin
Date: Thu Jul 06 2017 - 11:16:32 EST

On Wed, 5 Jul 2017 22:08:15 +0530
"Gautham R. Shenoy" <ego@xxxxxxxxxxxxxxxxxx> wrote:

> From: "Gautham R. Shenoy" <ego@xxxxxxxxxxxxxxxxxx>
> On POWER9 DD1, in order to get around a hardware issue, we store in
> every CPU thread's paca the paca pointers of all its siblings.
> Move this code into pnv_alloc_idle_core_states() soon after the space
> for saving the sibling pacas is allocated.
> Signed-off-by: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx>

> - if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
> - int cpu;
> -
> - pr_info("powernv: idle: Saving PACA pointers of all CPUs in their thread sibling PACA\n");
> - for_each_possible_cpu(cpu) {
> - int base_cpu = cpu_first_thread_sibling(cpu);
> - int idx = cpu_thread_in_core(cpu);
> - int i;
> -

You could move the thread_sibling_pacas allocation to here?

Speaking of which... core_idle_state and thread_sibling_pacas are
allocated with kmalloc_node... What happens if we take an SLB miss
in the idle wakeup code on these guys? Nothing good I think. Perhaps
we should put them into the pacas or somewhere in bolted memory.

Good cleanup though.

Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>