Commit fa35e868 authored by Srikar Dronamraju's avatar Srikar Dronamraju Committed by Michael Ellerman
Browse files

powerpc/smp: Implement cpu_to_coregroup_id 



Lookup the coregroup id from the associativity array.

If unable to detect the coregroup id, fallback on the core id.
This way, ensure sched_domain degenerates and an extra sched domain is
not created.

Ideally this function should have been implemented in
arch/powerpc/kernel/smp.c. However if its implemented in mm/numa.c, we
don't need to find the primary domain again.

If the device-tree mentions more than one coregroup, then kernel
implements only the last or the smallest coregroup, which currently
corresponds to the penultimate domain in the device-tree.

Signed-off-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: default avatarGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-11-srikar@linux.vnet.ibm.com
parent 72730bfc

arch/powerpc/mm/numa.c

+20 −0
Original line number Diff line number Diff line
@@ -1247,6 +1247,26 @@ int find_and_online_cpu_nid(int cpu) 


int cpu_to_coregroup_id(int cpu)

{

	__be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};

	int index;



	if (cpu < 0 || cpu > nr_cpu_ids)

		return -1;



	if (!coregroup_enabled)

		goto out;



	if (!firmware_has_feature(FW_FEATURE_VPHN))

		goto out;



	if (vphn_get_associativity(cpu, associativity))

		goto out;



	index = of_read_number(associativity, 1);

	if (index > min_common_depth + 1)

		return of_read_number(&associativity[index - 1], 1);



out:

	return cpu_to_core_id(cpu);

}