MIPS: c-r4k: Exclude sibling CPUs in SMP calls

When performing SMP calls to foreign cores, exclude sibling CPUs from
the provided map, as we already handle the local core on the current
CPU. This prevents an SMP call from for example core 0, VPE 1 to VPE 0
on the same core.

In the process the cpu_foreign_map cpumask is turned into an array of
cpumasks, so that each CPU has its own version of it which excludes
sibling CPUs. r4k_op_needs_ipi() is also updated to reflect that cache
management SMP calls are not needed when all CPUs are siblings (i.e.
there are no foreign CPUs according to the new cpu_foreign_map[]
semantics which exclude siblings).

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: Felix Fietkau <nbd@nbd.name>
Cc: Jayachandran C. <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13801/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 783d5f5..f95f094 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -72,7 +72,7 @@ EXPORT_SYMBOL(cpu_core_map);
  * A logcal cpu mask containing only one VPE per core to
  * reduce the number of IPIs on large MT systems.
  */
-cpumask_t cpu_foreign_map __read_mostly;
+cpumask_t cpu_foreign_map[NR_CPUS] __read_mostly;
 EXPORT_SYMBOL(cpu_foreign_map);
 
 /* representing cpus for which sibling maps can be computed */
@@ -141,7 +141,9 @@ void calculate_cpu_foreign_map(void)
 			cpumask_set_cpu(i, &temp_foreign_map);
 	}
 
-	cpumask_copy(&cpu_foreign_map, &temp_foreign_map);
+	for_each_online_cpu(i)
+		cpumask_andnot(&cpu_foreign_map[i],
+			       &temp_foreign_map, &cpu_sibling_map[i]);
 }
 
 struct plat_smp_ops *mp_ops;