arm64: Add CPU hotplug support

hulk inclusion
category: feature
bugzilla: 20208
CVE: NA
---------------------------

To support CPU hotplug, we need to implement 'acpi_(un)map_cpu()' and
'arch_(un)register_cpu()' for ARM64. These functions are called in
'acpi_processor_hotadd_init()/acpi_processor_remove()' when the CPU is hot
added into or hot removed from the system.

Note: This patch only support core hotplug and does not support socket
hotplug because we don't support live configuration of GIC.
Signed-off-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Acked-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/kernel/acpi.c

@@ -28,6 +28,7 @@
 #include <linux/smp.h>
 #include <linux/serial_core.h>
 
+#include <acpi/processor.h>
 #include <asm/cputype.h>
 #include <asm/cpu_ops.h>
 #include <asm/pgtable.h>
@@ -261,3 +262,31 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
 		return __pgprot(PROT_NORMAL_NC);
 	return __pgprot(PROT_DEVICE_nGnRnE);
 }
+
+int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id,
+		 int *pcpu)
+{
+	int cpu, nid;
+
+	cpu = acpi_map_cpuid(physid, acpi_id);
+	nid = acpi_get_node(handle);
+	if (nid != NUMA_NO_NODE) {
+		set_cpu_numa_node(cpu, nid);
+		numa_add_cpu(cpu);
+	}
+
+	*pcpu = cpu;
+	set_cpu_present(cpu, true);
+
+	return 0;
+}
+EXPORT_SYMBOL(acpi_map_cpu);
+
+int acpi_unmap_cpu(int cpu)
+{
+	set_cpu_present(cpu, false);
+	numa_clear_node(cpu);
+
+	return 0;
+}
+EXPORT_SYMBOL(acpi_unmap_cpu);

arch/arm64/kernel/setup.c

@@ -429,3 +429,20 @@ static int __init register_kernel_offset_dumper(void)
 	return 0;
 }
 __initcall(register_kernel_offset_dumper);
+
+int arch_register_cpu(int num)
+{
+	struct cpu *cpu = &per_cpu(cpu_data.cpu, num);
+
+	cpu->hotpluggable = 1;
+	return register_cpu(cpu, num);
+}
+EXPORT_SYMBOL(arch_register_cpu);
+
+void arch_unregister_cpu(int num)
+{
+	struct cpu *cpu = &per_cpu(cpu_data.cpu, num);
+
+	unregister_cpu(cpu);
+}
+EXPORT_SYMBOL(arch_unregister_cpu);