arm64: topology: add support to remove cpu topology sibling masks

This patch adds support to remove all the CPU topology information using
clear_cpu_topology and also resetting the sibling information on other
sibling CPUs. This will be used in cpu_disable so that all the topology
sibling information is removed on CPU hotplug out.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Tested-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/topology.h

@@ -20,9 +20,11 @@ extern struct cpu_topology cpu_topology[NR_CPUS];
 #define topology_core_id(cpu)		(cpu_topology[cpu].core_id)
 #define topology_core_cpumask(cpu)	(&cpu_topology[cpu].core_sibling)
 #define topology_sibling_cpumask(cpu)	(&cpu_topology[cpu].thread_sibling)
+#define topology_llc_cpumask(cpu)	(&cpu_topology[cpu].llc_siblings)
 
 void init_cpu_topology(void);
 void store_cpu_topology(unsigned int cpuid);
+void remove_cpu_topology(unsigned int cpuid);
 const struct cpumask *cpu_coregroup_mask(int cpu);
 
 #ifdef CONFIG_NUMA

arch/arm64/kernel/topology.c

@@ -322,6 +322,20 @@ static void __init reset_cpu_topology(void)
 	}
 }
 
+void remove_cpu_topology(unsigned int cpu)
+{
+	int sibling;
+
+	for_each_cpu(sibling, topology_core_cpumask(cpu))
+		cpumask_clear_cpu(cpu, topology_core_cpumask(sibling));
+	for_each_cpu(sibling, topology_sibling_cpumask(cpu))
+		cpumask_clear_cpu(cpu, topology_sibling_cpumask(sibling));
+	for_each_cpu(sibling, topology_llc_cpumask(cpu))
+		cpumask_clear_cpu(cpu, topology_llc_cpumask(sibling));
+
+	clear_cpu_topology(cpu);
+}
+
 #ifdef CONFIG_ACPI
 /*
  * Propagate the topology information of the processor_topology_node tree to the