LoongArch: For all possible CPUs setup logical-physical CPU mapping

In order to support ACPI-based physical CPU hotplug, we suppose for all
"possible" CPUs cpu_logical_map() can work. Because some drivers want to
use cpu_logical_map() for all "possible" CPUs, while currently we only
setup logical-physical mapping for "present" CPUs. This lack of mapping
also causes cpu_to_node() cannot work for hot-added CPUs.

All "possible" CPUs are listed in MADT, and the "present" subset is
marked as ACPI_MADT_ENABLED. To setup logical-physical CPU mapping for
all possible CPUs and keep present CPUs continuous in cpu_present_mask,
we parse MADT twice. The first pass handles CPUs with ACPI_MADT_ENABLED
and the second pass handles CPUs without ACPI_MADT_ENABLED.

The global flag (cpu_enumerated) is removed because acpi_map_cpu() calls
cpu_number_map() rather than set_processor_mask() now.

Reported-by: Bibo Mao <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>

arch/loongarch/kernel/acpi.c

@@ -58,48 +58,48 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
 		return ioremap_cache(phys, size);
 }
 
-static int cpu_enumerated = 0;
-
 #ifdef CONFIG_SMP
-static int set_processor_mask(u32 id, u32 flags)
+static int set_processor_mask(u32 id, u32 pass)
 {
-	int nr_cpus;
-	int cpu, cpuid = id;
-
-	if (!cpu_enumerated)
-		nr_cpus = NR_CPUS;
-	else
-		nr_cpus = nr_cpu_ids;
+	int cpu = -1, cpuid = id;
 
-	if (num_processors >= nr_cpus) {
+	if (num_processors >= NR_CPUS) {
 		pr_warn(PREFIX "nr_cpus limit of %i reached."
-			" processor 0x%x ignored.\n", nr_cpus, cpuid);
+			" processor 0x%x ignored.\n", NR_CPUS, cpuid);
 
 		return -ENODEV;
 
 	}
+
 	if (cpuid == loongson_sysconf.boot_cpu_id)
 		cpu = 0;
-	else
-		cpu = find_first_zero_bit(cpumask_bits(cpu_present_mask), NR_CPUS);
-
-	if (!cpu_enumerated)
-		set_cpu_possible(cpu, true);
 
-	if (flags & ACPI_MADT_ENABLED) {
+	switch (pass) {
+	case 1: /* Pass 1 handle enabled processors */
+		if (cpu < 0)
+			cpu = find_first_zero_bit(cpumask_bits(cpu_present_mask), NR_CPUS);
 		num_processors++;
 		set_cpu_present(cpu, true);
-		__cpu_number_map[cpuid] = cpu;
-		__cpu_logical_map[cpu] = cpuid;
-	} else
+		break;
+	case 2: /* Pass 2 handle disabled processors */
+		if (cpu < 0)
+			cpu = find_first_zero_bit(cpumask_bits(cpu_possible_mask), NR_CPUS);
 		disabled_cpus++;
+		break;
+	default:
+		return cpu;
+	}
+
+	set_cpu_possible(cpu, true);
+	__cpu_number_map[cpuid] = cpu;
+	__cpu_logical_map[cpu] = cpuid;
 
 	return cpu;
 }
 #endif
 
 static int __init
-acpi_parse_processor(union acpi_subtable_headers *header, const unsigned long end)
+acpi_parse_p1_processor(union acpi_subtable_headers *header, const unsigned long end)
 {
 	struct acpi_madt_core_pic *processor = NULL;
 
@@ -110,12 +110,29 @@ acpi_parse_processor(union acpi_subtable_headers *header, const unsigned long en
 	acpi_table_print_madt_entry(&header->common);
 #ifdef CONFIG_SMP
 	acpi_core_pic[processor->core_id] = *processor;
-	set_processor_mask(processor->core_id, processor->flags);
+	if (processor->flags & ACPI_MADT_ENABLED)
+		set_processor_mask(processor->core_id, 1);
 #endif
 
 	return 0;
 }
 
+static int __init
+acpi_parse_p2_processor(union acpi_subtable_headers *header, const unsigned long end)
+{
+	struct acpi_madt_core_pic *processor = NULL;
+
+	processor = (struct acpi_madt_core_pic *)header;
+	if (BAD_MADT_ENTRY(processor, end))
+		return -EINVAL;
+
+#ifdef CONFIG_SMP
+	if (!(processor->flags & ACPI_MADT_ENABLED))
+		set_processor_mask(processor->core_id, 2);
+#endif
+
+	return 0;
+}
 static int __init
 acpi_parse_eio_master(union acpi_subtable_headers *header, const unsigned long end)
 {
@@ -143,12 +160,14 @@ static void __init acpi_process_madt(void)
 	}
 #endif
 	acpi_table_parse_madt(ACPI_MADT_TYPE_CORE_PIC,
-			acpi_parse_processor, MAX_CORE_PIC);
+			acpi_parse_p1_processor, MAX_CORE_PIC);
+
+	acpi_table_parse_madt(ACPI_MADT_TYPE_CORE_PIC,
+			acpi_parse_p2_processor, MAX_CORE_PIC);
 
 	acpi_table_parse_madt(ACPI_MADT_TYPE_EIO_PIC,
 			acpi_parse_eio_master, MAX_IO_PICS);
 
-	cpu_enumerated = 1;
 	loongson_sysconf.nr_cpus = num_processors;
 }
 
@@ -324,10 +343,10 @@ int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id, int *pcpu
 {
 	int cpu;
 
-	cpu = set_processor_mask(physid, ACPI_MADT_ENABLED);
-	if (cpu < 0) {
+	cpu = cpu_number_map(physid);
+	if (cpu < 0 || cpu >= nr_cpu_ids) {
 		pr_info(PREFIX "Unable to map lapic to logical cpu number\n");
-		return cpu;
+		return -ERANGE;
 	}
 
 	acpi_map_cpu2node(handle, cpu, physid);