ACPI/arm64: add support for virtual cpuhotplug

index 2019c1f04bd0..444154271f23 100644
@@ -404,13 +404,7 @@ static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
 
 void __init smp_prepare_boot_cpu(void)
 {
-	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
-
-	/* Setup BSP mappings */
-	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
-
-	set_cpu_online(bootstrap_processor, true);
-	set_cpu_present(bootstrap_processor, true);
+	pr_info("SMP: bootstrap CPU ID is 0\n");
 }
 
 

index 691d4b7686ee..ed01e19514ef 100644
@@ -304,7 +304,7 @@ static int acpi_scan_device_check(struct acpi_device *adev)
 	int error;
 
 	acpi_bus_get_status(adev);
-	if (adev->status.present || adev->status.functional) {
+	if (acpi_device_is_present(adev)) {
 		/*
 		 * This function is only called for device objects for which
 		 * matching scan handlers exist.  The only situation in which

@@ -338,7 +338,7 @@ static int acpi_scan_bus_check(struct acpi_device *adev, void *not_used)
 	int error;
 
 	acpi_bus_get_status(adev);
-	if (!(adev->status.present || adev->status.functional)) {
+	if (!acpi_device_is_present(adev)) {
 		acpi_scan_device_not_present(adev);
 		return 0;
 	}

index ed01e19514ef..17ab875a7d4e 100644
@@ -289,10 +289,10 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
 	return 0;
 }
 
-static int acpi_scan_device_not_present(struct acpi_device *adev)
+static int acpi_scan_device_not_enumerated(struct acpi_device *adev)
 {
 	if (!acpi_device_enumerated(adev)) {
-		dev_warn(&adev->dev, "Still not present\n");
+		dev_warn(&adev->dev, "Still not enumerated\n");
 		return -EALREADY;
 	}
 	acpi_bus_trim(adev);

@@ -327,7 +327,7 @@ static int acpi_scan_device_check(struct acpi_device *adev)
 			error = -ENODEV;
 		}
 	} else {
-		error = acpi_scan_device_not_present(adev);
+		error = acpi_scan_device_not_enumerated(adev);
 	}
 	return error;
 }

@@ -339,7 +339,7 @@ static int acpi_scan_bus_check(struct acpi_device *adev, void *not_used)
 
 	acpi_bus_get_status(adev);
 	if (!acpi_device_is_present(adev)) {
-		acpi_scan_device_not_present(adev);
+		acpi_scan_device_not_enumerated(adev);
 		return 0;
 	}
 	if (handler && handler->hotplug.scan_dependent)

index 960b98b43506..8c8f55721786 100644
@@ -520,7 +520,7 @@ acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
 {
 	u64 hwid = processor->arm_mpidr;
 
-	if (!(processor->flags & ACPI_MADT_ENABLED)) {
+	if (!acpi_gicc_is_usable(processor)) {
 		pr_debug("skipping disabled CPU entry with 0x%llx MPIDR\n", hwid);
 		return;
 	}

index 7dd6dbaa98c3..b203cfe28550 100644
@@ -90,7 +90,7 @@ static int map_gicc_mpidr(struct acpi_subtable_header *entry,
 	struct acpi_madt_generic_interrupt *gicc =
 	    container_of(entry, struct acpi_madt_generic_interrupt, header);
 
-	if (!(gicc->flags & ACPI_MADT_ENABLED))
+	if (!acpi_gicc_is_usable(gicc))
 		return -ENODEV;
 
 	/* device_declaration means Device object in DSDT, in the

index f59ac9586b7b..d50d9414f471 100644
@@ -2380,8 +2380,7 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
 	u32 size = reg == GIC_PIDR2_ARCH_GICv4 ? SZ_64K * 4 : SZ_64K * 2;
 	void __iomem *redist_base;
 
-	/* GICC entry which has !ACPI_MADT_ENABLED is not unusable so skip */
-	if (!(gicc->flags & ACPI_MADT_ENABLED))
+	if (!acpi_gicc_is_usable(gicc))
 		return 0;
 
 	redist_base = ioremap(gicc->gicr_base_address, size);

@@ -2431,7 +2430,7 @@ static int __init gic_acpi_match_gicc(union acpi_subtable_headers *header,
 	 * If GICC is enabled and has valid gicr base address, then it means
 	 * GICR base is presented via GICC
 	 */
-	if ((gicc->flags & ACPI_MADT_ENABLED) && gicc->gicr_base_address) {
+	if (acpi_gicc_is_usable(gicc) && gicc->gicr_base_address) {
 		acpi_data.enabled_rdists++;
 		return 0;
 	}

@@ -2440,7 +2439,7 @@ static int __init gic_acpi_match_gicc(union acpi_subtable_headers *header,
 	 * It's perfectly valid firmware can pass disabled GICC entry, driver
 	 * should not treat as errors, skip the entry instead of probe fail.
 	 */
-	if (!(gicc->flags & ACPI_MADT_ENABLED))
+	if (!acpi_gicc_is_usable(gicc))
 		return 0;
 
 	return -ENODEV;

@@ -2499,8 +2498,7 @@ static int __init gic_acpi_parse_virt_madt_gicc(union acpi_subtable_headers *hea
 	int maint_irq_mode;
 	static int first_madt = true;
 
-	/* Skip unusable CPUs */
-	if (!(gicc->flags & ACPI_MADT_ENABLED))
+	if (!acpi_gicc_is_usable(gicc))
 		return 0;
 
 	maint_irq_mode = (gicc->flags & ACPI_MADT_VGIC_IRQ_MODE) ?

index afd94c9b8b8a..ebfea7bf663d 100644
@@ -256,6 +256,11 @@ acpi_table_parse_cedt(enum acpi_cedt_type id,
 int acpi_parse_mcfg (struct acpi_table_header *header);
 void acpi_table_print_madt_entry (struct acpi_subtable_header *madt);
 
+static inline bool acpi_gicc_is_usable(struct acpi_madt_generic_interrupt *gicc)
+{
+	return gicc->flags & ACPI_MADT_ENABLED;
+}
+
 /* the following numa functions are architecture-dependent */
 void acpi_numa_slit_init (struct acpi_table_slit *slit);
 

index 0f5218e361df..4fe2ef54088c 100644
@@ -184,24 +184,6 @@ static void __init acpi_pcc_cpufreq_init(void) {}
 
 /* Initialization */
 #ifdef CONFIG_ACPI_HOTPLUG_CPU
-int __weak acpi_map_cpu(acpi_handle handle,
-		phys_cpuid_t physid, u32 acpi_id, int *pcpu)
-{
-	return -ENODEV;
-}
-
-int __weak acpi_unmap_cpu(int cpu)
-{
-	return -ENODEV;
-}
-
-int __weak arch_register_cpu(int cpu)
-{
-	return -ENODEV;
-}
-
-void __weak arch_unregister_cpu(int cpu) {}
-
 static int acpi_processor_hotadd_init(struct acpi_processor *pr)
 {
 	unsigned long long sta;

index 9ea22e165acd..34b48f660b6b 100644
@@ -533,7 +533,7 @@ static void __init cpu_dev_register_generic(void)
 #ifdef CONFIG_GENERIC_CPU_DEVICES
 	int i;
 
-	for_each_possible_cpu(i) {
+	for_each_present_cpu(i) {
 		if (register_cpu(&per_cpu(cpu_devices, i), i))
 			panic("Failed to register CPU device");
 	}

index 34b48f660b6b..579064fda97b 100644
@@ -525,19 +525,25 @@ bool cpu_is_hotpluggable(unsigned int cpu)
 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
 
 #ifdef CONFIG_GENERIC_CPU_DEVICES
-static DEFINE_PER_CPU(struct cpu, cpu_devices);
+DEFINE_PER_CPU(struct cpu, cpu_devices);
+
+int __weak arch_register_cpu(int cpu)
+{
+	return register_cpu(&per_cpu(cpu_devices, cpu), cpu);
+}
 #endif
 
 static void __init cpu_dev_register_generic(void)
 {
-#ifdef CONFIG_GENERIC_CPU_DEVICES
 	int i;
 
+	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES))
+		return;
+
 	for_each_present_cpu(i) {
-		if (register_cpu(&per_cpu(cpu_devices, i), i))
+		if (arch_register_cpu(i))
 			panic("Failed to register CPU device");
 	}
-#endif
 }
 
 #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES

index eb768a866fe3..e117c06e0c6b 100644
@@ -88,6 +88,10 @@ extern ssize_t arch_cpu_probe(const char *, size_t);
 extern ssize_t arch_cpu_release(const char *, size_t);
 #endif
 
+#ifdef CONFIG_GENERIC_CPU_DEVICES
+DECLARE_PER_CPU(struct cpu, cpu_devices);
+#endif
+
 /*
  * These states are not related to the core CPU hotplug mechanism. They are
  * used by various (sub)architectures to track internal state

index 397eb9880cec..c4954835128c 100644
@@ -35,8 +35,8 @@ void __init driver_init(void)
 	of_core_init();
 	platform_bus_init();
 	auxiliary_bus_init();
-	cpu_dev_init();
 	memory_dev_init();
 	node_dev_init();
+	cpu_dev_init();
 	container_dev_init();
 }

index 493d533f8375..4d5ac7cf8757 100644
@@ -867,7 +867,6 @@ void register_memory_blocks_under_node(int nid, unsigned long start_pfn,
 int __register_one_node(int nid)
 {
 	int error;
-	int cpu;
 
 	node_devices[nid] = kzalloc(sizeof(struct node), GFP_KERNEL);
 	if (!node_devices[nid])

@@ -875,12 +874,6 @@ int __register_one_node(int nid)
 
 	error = register_node(node_devices[nid], nid);
 
-	/* link cpu under this node */
-	for_each_present_cpu(cpu) {
-		if (cpu_to_node(cpu) == nid)
-			register_cpu_under_node(cpu, nid);
-	}
-
 	INIT_LIST_HEAD(&node_devices[nid]->access_list);
 	node_init_caches(nid);
 

index 579064fda97b..d31c936f0955 100644
@@ -535,14 +535,15 @@ int __weak arch_register_cpu(int cpu)
 
 static void __init cpu_dev_register_generic(void)
 {
-	int i;
+	int i, ret;
 
 	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES))
 		return;
 
 	for_each_present_cpu(i) {
-		if (arch_register_cpu(i))
-			panic("Failed to register CPU device");
+		ret = arch_register_cpu(i);
+		if (ret)
+			pr_warn("register_cpu %d failed (%d)\n", i, ret);
 	}
 }
 

index e749838b9c5d..887bd0d992bb 100644
@@ -38,7 +38,6 @@ struct cpuinfo_32bit {
 };
 
 struct cpuinfo_arm64 {
-	struct cpu	cpu;
 	struct kobject	kobj;
 	u64		reg_ctr;
 	u64		reg_cntfrq;

index 417a8a86b2db..165bd2c0dd5a 100644
@@ -402,19 +402,14 @@ static inline bool cpu_can_disable(unsigned int cpu)
 	return false;
 }
 
-static int __init topology_init(void)
+int arch_register_cpu(int num)
 {
-	int i;
+	struct cpu *cpu = &per_cpu(cpu_devices, num);
 
-	for_each_possible_cpu(i) {
-		struct cpu *cpu = &per_cpu(cpu_data.cpu, i);
-		cpu->hotpluggable = cpu_can_disable(i);
-		register_cpu(cpu, i);
-	}
+	cpu->hotpluggable = cpu_can_disable(num);
 
-	return 0;
+	return register_cpu(cpu, num);
 }
-subsys_initcall(topology_init);
 
 static void dump_kernel_offset(void)
 {

index 642d71675ddb..3b36c6a382bb 100644
@@ -7,12 +7,6 @@
 #include <linux/topology.h>
 #include <linux/percpu.h>
 
-struct ia64_cpu {
-	struct cpu cpu;
-};
-
-DECLARE_PER_CPU(struct ia64_cpu, cpu_devices);
-
 DECLARE_PER_CPU(int, cpu_state);
 
 #endif /* _ASM_IA64_CPU_H_ */

index 741863a187a6..8f5cafde2bc9 100644
@@ -26,8 +26,6 @@
 #include <asm/numa.h>
 #include <asm/cpu.h>
 
-static struct ia64_cpu *sysfs_cpus;
-
 void arch_fix_phys_package_id(int num, u32 slot)
 {
 #ifdef CONFIG_SMP

@@ -41,50 +39,27 @@ EXPORT_SYMBOL_GPL(arch_fix_phys_package_id);
 #ifdef CONFIG_HOTPLUG_CPU
 int __ref arch_register_cpu(int num)
 {
+	struct cpu *cpu = &per_cpu(cpu_devices, num);
+
 	/*
 	 * If CPEI can be re-targeted or if this is not
 	 * CPEI target, then it is hotpluggable
 	 */
 	if (can_cpei_retarget() || !is_cpu_cpei_target(num))
-		sysfs_cpus[num].cpu.hotpluggable = 1;
+		cpu->hotpluggable = 1;
 	map_cpu_to_node(num, node_cpuid[num].nid);
-	return register_cpu(&sysfs_cpus[num].cpu, num);
+	return register_cpu(cpu, num);
 }
 EXPORT_SYMBOL(arch_register_cpu);
 
 void __ref arch_unregister_cpu(int num)
 {
-	unregister_cpu(&sysfs_cpus[num].cpu);
+	unregister_cpu(&per_cpu(cpu_devices, num));
 	unmap_cpu_from_node(num, cpu_to_node(num));
 }
 EXPORT_SYMBOL(arch_unregister_cpu);
-#else
-int __init arch_register_cpu(int num)
-{
-	return register_cpu(&sysfs_cpus[num].cpu, num);
-}
 #endif /*CONFIG_HOTPLUG_CPU*/
 
-
-static int __init topology_init(void)
-{
-	int i, err = 0;
-
-	sysfs_cpus = kcalloc(NR_CPUS, sizeof(struct ia64_cpu), GFP_KERNEL);
-	if (!sysfs_cpus)
-		panic("kzalloc in topology_init failed - NR_CPUS too big?");
-
-	for_each_present_cpu(i) {
-		if((err = arch_register_cpu(i)))
-			goto out;
-	}
-out:
-	return err;
-}
-
-subsys_initcall(topology_init);
-
-
 /*
  * Export cpu cache information through sysfs
  */

index e4c3ba91321c..f18d35fe27a9 100644
@@ -237,4 +237,4 @@ static __init int intel_epb_init(void)
 	cpuhp_remove_state(CPUHP_AP_X86_INTEL_EPB_ONLINE);
 	return ret;
 }
-subsys_initcall(intel_epb_init);
+late_initcall(intel_epb_init);

index 25050d953eee..91867a6a9f8e 100644
@@ -23,10 +23,6 @@ static inline void prefill_possible_map(void) {}
 
 #endif /* CONFIG_SMP */
 
-struct x86_cpu {
-	struct cpu cpu;
-};
-
 #ifdef CONFIG_HOTPLUG_CPU
 extern void soft_restart_cpu(void);
 #endif

index 0bab03130033..027897054424 100644
@@ -35,38 +35,19 @@
 #include <asm/io_apic.h>
 #include <asm/cpu.h>
 
-static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
-
 #ifdef CONFIG_HOTPLUG_CPU
 int arch_register_cpu(int cpu)
 {
-	struct x86_cpu *xc = per_cpu_ptr(&cpu_devices, cpu);
+	struct cpu *c = per_cpu_ptr(&cpu_devices, cpu);
 
-	xc->cpu.hotpluggable = cpu > 0;
-	return register_cpu(&xc->cpu, cpu);
+	c->hotpluggable = cpu > 0;
+	return register_cpu(c, cpu);
 }
 EXPORT_SYMBOL(arch_register_cpu);
 
 void arch_unregister_cpu(int num)
 {
-	unregister_cpu(&per_cpu(cpu_devices, num).cpu);
+	unregister_cpu(&per_cpu(cpu_devices, num));
 }
 EXPORT_SYMBOL(arch_unregister_cpu);
-#else /* CONFIG_HOTPLUG_CPU */
-
-int __init arch_register_cpu(int num)
-{
-	return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
-}
 #endif /* CONFIG_HOTPLUG_CPU */
-
-static int __init topology_init(void)
-{
-	int i;
-
-	for_each_present_cpu(i)
-		arch_register_cpu(i);
-
-	return 0;
-}
-subsys_initcall(topology_init);

index 3fd166006698..bf58351beac1 100644
@@ -10,20 +10,13 @@
 
 #include <acpi/processor.h>
 
-static DEFINE_PER_CPU(struct cpu, cpu_devices);
-
 #ifdef CONFIG_HOTPLUG_CPU
 int arch_register_cpu(int cpu)
 {
-	int ret;
 	struct cpu *c = &per_cpu(cpu_devices, cpu);
 
-	c->hotpluggable = 1;
-	ret = register_cpu(c, cpu);
-	if (ret < 0)
-		pr_warn("register_cpu %d failed (%d)\n", cpu, ret);
-
-	return ret;
+	c->hotpluggable = !io_master(cpu);
+	return register_cpu(c, cpu);
 }
 EXPORT_SYMBOL(arch_register_cpu);
 

@@ -36,21 +29,3 @@ void arch_unregister_cpu(int cpu)
 }
 EXPORT_SYMBOL(arch_unregister_cpu);
 #endif
-
-static int __init topology_init(void)
-{
-	int i, ret;
-
-	for_each_present_cpu(i) {
-		struct cpu *c = &per_cpu(cpu_devices, i);
-
-		c->hotpluggable = !io_master(i);
-		ret = register_cpu(c, i);
-		if (ret < 0)
-			pr_warn("topology_init: register_cpu %d failed (%d)\n", i, ret);
-	}
-
-	return 0;
-}
-
-subsys_initcall(topology_init);

index aac853ae4eb7..311e99741cf8 100644
@@ -62,7 +62,6 @@ atomic_t hart_lottery __section(".sdata")
 #endif
 ;
 unsigned long boot_cpu_hartid;
-static DEFINE_PER_CPU(struct cpu, cpu_devices);
 
 /*
  * Place kernel memory regions on the resource tree so that

@@ -307,23 +306,13 @@ void __init setup_arch(char **cmdline_p)
 	riscv_set_dma_cache_alignment();
 }
 
-static int __init topology_init(void)
+int arch_register_cpu(int cpu)
 {
-	int i, ret;
+	struct cpu *c = &per_cpu(cpu_devices, cpu);
 
-	for_each_possible_cpu(i) {
-		struct cpu *cpu = &per_cpu(cpu_devices, i);
-
-		cpu->hotpluggable = cpu_has_hotplug(i);
-		ret = register_cpu(cpu, i);
-		if (unlikely(ret))
-			pr_warn("Warning: %s: register_cpu %d failed (%d)\n",
-			       __func__, i, ret);
-	}
-
-	return 0;
+	c->hotpluggable = cpu_has_hotplug(cpu);
+	return register_cpu(c, cpu);
 }
-subsys_initcall(topology_init);
 
 void free_initmem(void)
 {

index b741b5ba82bd..9ccb7daee78e 100644
@@ -220,20 +220,34 @@ static DECLARE_WORK(update_topology_flags_work, update_topology_flags_workfn);
 
 static DEVICE_ATTR_RO(cpu_capacity);
 
-static int register_cpu_capacity_sysctl(void)
+static int cpu_capacity_sysctl_add(unsigned int cpu)
 {
-	int i;
-	struct device *cpu;
+	struct device *cpu_dev = get_cpu_device(cpu);
 
-	for_each_possible_cpu(i) {
-		cpu = get_cpu_device(i);
-		if (!cpu) {
-			pr_err("%s: too early to get CPU%d device!\n",
-			       __func__, i);
-			continue;
-		}
-		device_create_file(cpu, &dev_attr_cpu_capacity);
-	}
+	if (!cpu_dev)
+		return -ENOENT;
+
+	device_create_file(cpu_dev, &dev_attr_cpu_capacity);
+
+	return 0;
+}
+
+static int cpu_capacity_sysctl_remove(unsigned int cpu)
+{
+	struct device *cpu_dev = get_cpu_device(cpu);
+
+	if (!cpu_dev)
+		return -ENOENT;
+
+	device_remove_file(cpu_dev, &dev_attr_cpu_capacity);
+
+	return 0;
+}
+
+static int register_cpu_capacity_sysctl(void)
+{
+	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "topology/cpu-capacity",
+			  cpu_capacity_sysctl_add, cpu_capacity_sysctl_remove);
 
 	return 0;
 }

index f007116a8427..76c38478a502 100644
@@ -313,7 +313,7 @@ int acpi_bus_init_power(struct acpi_device *device)
 		return -EINVAL;
 
 	device->power.state = ACPI_STATE_UNKNOWN;
-	if (!acpi_device_is_present(device)) {
+	if (!acpi_dev_ready_for_enumeration(device)) {
 		device->flags.initialized = false;
 		return -ENXIO;
 	}

index b9bbf0746199..16e586d74aa2 100644
@@ -141,7 +141,7 @@ static int create_pnp_modalias(const struct acpi_device *acpi_dev, char *modalia
 	struct acpi_hardware_id *id;
 
 	/* Avoid unnecessarily loading modules for non present devices. */
-	if (!acpi_device_is_present(acpi_dev))
+	if (!acpi_dev_ready_for_enumeration(acpi_dev))
 		return 0;
 
 	/*

index 866c7c4ed233..a1b45e345bcc 100644
@@ -107,7 +107,6 @@ int acpi_device_setup_files(struct acpi_device *dev);
 void acpi_device_remove_files(struct acpi_device *dev);
 void acpi_device_add_finalize(struct acpi_device *device);
 void acpi_free_pnp_ids(struct acpi_device_pnp *pnp);
-bool acpi_device_is_present(const struct acpi_device *adev);
 bool acpi_device_is_battery(struct acpi_device *adev);
 bool acpi_device_is_first_physical_node(struct acpi_device *adev,
 					const struct device *dev);

index 413e4fcadcaf..e03f00b98701 100644
@@ -1418,7 +1418,7 @@ static bool acpi_fwnode_device_is_available(const struct fwnode_handle *fwnode)
 	if (!is_acpi_device_node(fwnode))
 		return false;
 
-	return acpi_device_is_present(to_acpi_device_node(fwnode));
+	return acpi_dev_ready_for_enumeration(to_acpi_device_node(fwnode));
 }
 
 static const void *

index 17ab875a7d4e..06e9bb4a633f 100644
@@ -304,7 +304,7 @@ static int acpi_scan_device_check(struct acpi_device *adev)
 	int error;
 
 	acpi_bus_get_status(adev);
-	if (acpi_device_is_present(adev)) {
+	if (acpi_dev_ready_for_enumeration(adev)) {
 		/*
 		 * This function is only called for device objects for which
 		 * matching scan handlers exist.  The only situation in which

@@ -338,7 +338,7 @@ static int acpi_scan_bus_check(struct acpi_device *adev, void *not_used)
 	int error;
 
 	acpi_bus_get_status(adev);
-	if (!acpi_device_is_present(adev)) {
+	if (!acpi_dev_ready_for_enumeration(adev)) {
 		acpi_scan_device_not_enumerated(adev);
 		return 0;
 	}

@@ -1908,11 +1908,6 @@ static bool acpi_device_should_be_hidden(acpi_handle handle)
 	return true;
 }
 
-bool acpi_device_is_present(const struct acpi_device *adev)
-{
-	return adev->status.present || adev->status.functional;
-}
-
 static bool acpi_scan_handler_matching(struct acpi_scan_handler *handler,
 				       const char *idstr,
 				       const struct acpi_device_id **matchid)

@@ -2375,16 +2370,25 @@ EXPORT_SYMBOL_GPL(acpi_dev_clear_dependencies);
  * acpi_dev_ready_for_enumeration - Check if the ACPI device is ready for enumeration
  * @device: Pointer to the &struct acpi_device to check
  *
- * Check if the device is present and has no unmet dependencies.
+ * Check if the device is functional or enabled and has no unmet dependencies.
  *
- * Return true if the device is ready for enumeratino. Otherwise, return false.
+ * Return true if the device is ready for enumeration. Otherwise, return false.
  */
 bool acpi_dev_ready_for_enumeration(const struct acpi_device *device)
 {
 	if (device->flags.honor_deps && device->dep_unmet)
 		return false;
 
-	return acpi_device_is_present(device);
+	/*
+	 * ACPI 6.5's 6.3.7 "_STA (Device Status)" allows firmware to return
+	 * (!present && functional) for certain types of devices that should be
+	 * enumerated. Note that the enabled bit can't be sert until the present
+	 * bit is set.
+	 */
+	if (device->status.present)
+		return device->status.enabled;
+	else
+		return device->status.functional;
 }
 EXPORT_SYMBOL_GPL(acpi_dev_ready_for_enumeration);
 

index 4fe2ef54088c..6a542e0ce396 100644
@@ -626,9 +626,31 @@ static struct acpi_scan_handler processor_handler = {
 	},
 };
 
+static acpi_status acpi_processor_container_walk(acpi_handle handle,
+						 u32 lvl,
+						 void *context,
+						 void **rv)
+{
+	struct acpi_device *adev;
+	acpi_status status;
+
+	adev = acpi_get_acpi_dev(handle);
+	if (!adev)
+		return AE_ERROR;
+
+	status = acpi_processor_add(adev, &processor_device_ids[0]);
+	acpi_put_acpi_dev(adev);
+
+	return status;
+}
+
 static int acpi_processor_container_attach(struct acpi_device *dev,
 					   const struct acpi_device_id *id)
 {
+	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, dev->handle,
+			    ACPI_UINT32_MAX, acpi_processor_container_walk,
+			    NULL, NULL, NULL);
+
 	return 1;
 }
 

index 6a542e0ce396..0511f2bc10bc 100644
@@ -791,6 +791,25 @@ void __init acpi_processor_init(void)
 	acpi_pcc_cpufreq_init();
 }
 
+static int __init acpi_processor_register_missing_cpus(void)
+{
+	int cpu;
+
+	if (acpi_disabled)
+		return 0;
+
+	for_each_online_cpu(cpu) {
+		if (!get_cpu_device(cpu)) {
+			pr_err_once(FW_BUG "CPU %u has no ACPI namespace description!\n", cpu);
+			add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+			arch_register_cpu(cpu);
+		}
+	}
+
+	return 0;
+}
+subsys_initcall_sync(acpi_processor_register_missing_cpus);
+
 #ifdef CONFIG_ACPI_PROCESSOR_CSTATE
 /**
  * acpi_processor_claim_cst_control - Request _CST control from the platform.

index 0511f2bc10bc..e7ed4730cbbe 100644
@@ -314,6 +314,18 @@ static int acpi_processor_get_info(struct acpi_device *device)
 			cpufreq_add_device("acpi-cpufreq");
 	}
 
+	/*
+	 * Register CPUs that are present. get_cpu_device() is used to skip
+	 * duplicate CPU descriptions from firmware.
+	 */
+	if (!invalid_logical_cpuid(pr->id) && cpu_present(pr->id) &&
+	    !get_cpu_device(pr->id)) {
+		int ret = arch_register_cpu(pr->id);
+
+		if (ret)
+			return ret;
+	}
+
 	/*
 	 *  Extra Processor objects may be enumerated on MP systems with
 	 *  less than the max # of CPUs. They should be ignored _iff

index d31c936f0955..6c70a004c198 100644
@@ -537,7 +537,11 @@ static void __init cpu_dev_register_generic(void)
 {
 	int i, ret;
 
-	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES))
+	/*
+	 * When ACPI is enabled, CPUs are registered via
+	 * acpi_processor_get_info().
+	 */
+	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES) || !acpi_disabled)
 		return;
 
 	for_each_present_cpu(i) {

index 58500a964238..482ea994d1e1 100644
@@ -52,7 +52,7 @@ extern unsigned int is_cpu_cpei_target(unsigned int cpu);
 extern void set_cpei_target_cpu(unsigned int cpu);
 extern unsigned int get_cpei_target_cpu(void);
 extern void prefill_possible_map(void);
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 extern int additional_cpus;
 #else
 #define additional_cpus 0

index 41e8fe55cd98..381ce50fa54c 100644
@@ -194,7 +194,7 @@ acpi_parse_plat_int_src(union acpi_subtable_headers * header,
 	return 0;
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 unsigned int can_cpei_retarget(void)
 {
 	extern int cpe_vector;

@@ -711,7 +711,7 @@ int acpi_isa_irq_to_gsi(unsigned isa_irq, u32 *gsi)
 /*
  *  ACPI based hotplug CPU support
  */
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 int acpi_map_cpu2node(acpi_handle handle, int cpu, int physid)
 {
 #ifdef CONFIG_ACPI_NUMA

@@ -820,7 +820,7 @@ int acpi_unmap_cpu(int cpu)
 	return (0);
 }
 EXPORT_SYMBOL(acpi_unmap_cpu);
-#endif				/* CONFIG_ACPI_HOTPLUG_CPU */
+#endif				/* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
 
 #ifdef CONFIG_ACPI_NUMA
 static acpi_status acpi_map_iosapic(acpi_handle handle, u32 depth,

index 5a55ac82c13a..44591716d07b 100644
@@ -569,7 +569,7 @@ setup_arch (char **cmdline_p)
 #ifdef CONFIG_ACPI_NUMA
 	acpi_numa_init();
 	acpi_numa_fixup();
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 	prefill_possible_map();
 #endif
 	per_cpu_scan_finalize((cpumask_empty(&early_cpu_possible_map) ?

index 8e00a754e548..dfa56119b56f 100644
@@ -288,7 +288,7 @@ void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
 	memblock_reserve(addr, size);
 }
 
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 
 #include <acpi/processor.h>
 

@@ -340,4 +340,4 @@ int acpi_unmap_cpu(int cpu)
 }
 EXPORT_SYMBOL(acpi_unmap_cpu);
 
-#endif /* CONFIG_ACPI_HOTPLUG_CPU */
+#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */

index 2a0ea38955df..84dd4133754b 100644
@@ -814,7 +814,7 @@ static void __init acpi_set_irq_model_ioapic(void)
 /*
  *  ACPI based hotplug support for CPU
  */
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 #include <acpi/processor.h>
 
 static int acpi_map_cpu2node(acpi_handle handle, int cpu, int physid)

@@ -863,7 +863,7 @@ int acpi_unmap_cpu(int cpu)
 	return (0);
 }
 EXPORT_SYMBOL(acpi_unmap_cpu);
-#endif				/* CONFIG_ACPI_HOTPLUG_CPU */
+#endif				/* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
 
 int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base)
 {

index e7ed4730cbbe..c8e960ff0aca 100644
@@ -183,7 +183,7 @@ static void __init acpi_pcc_cpufreq_init(void) {}
 #endif /* CONFIG_X86 */
 
 /* Initialization */
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 static int acpi_processor_hotadd_init(struct acpi_processor *pr)
 {
 	unsigned long long sta;

@@ -228,7 +228,7 @@ static inline int acpi_processor_hotadd_init(struct acpi_processor *pr)
 {
 	return -ENODEV;
 }
-#endif /* CONFIG_ACPI_HOTPLUG_CPU */
+#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
 
 static int acpi_processor_get_info(struct acpi_device *device)
 {

@@ -461,7 +461,7 @@ static int acpi_processor_add(struct acpi_device *device,
 	return result;
 }
 
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 /* Removal */
 static void acpi_processor_remove(struct acpi_device *device)
 {

@@ -505,7 +505,7 @@ static void acpi_processor_remove(struct acpi_device *device)
 	free_cpumask_var(pr->throttling.shared_cpu_map);
 	kfree(pr);
 }
-#endif /* CONFIG_ACPI_HOTPLUG_CPU */
+#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
 
 #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC
 bool __init processor_physically_present(acpi_handle handle)

@@ -630,7 +630,7 @@ static const struct acpi_device_id processor_device_ids[] = {
 static struct acpi_scan_handler processor_handler = {
 	.ids = processor_device_ids,
 	.attach = acpi_processor_add,
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 	.detach = acpi_processor_remove,
 #endif
 	.hotplug = {

index ebfea7bf663d..48ee36086577 100644
@@ -321,12 +321,12 @@ static inline int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
 }
 #endif
 
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
+#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 /* Arch dependent functions for cpu hotplug support */
 int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id,
 		 int *pcpu);
 int acpi_unmap_cpu(int cpu);
-#endif /* CONFIG_ACPI_HOTPLUG_CPU */
+#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
 
 #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
 int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);

@@ -649,7 +649,7 @@ static inline u32 acpi_osc_ctx_get_cxl_control(struct acpi_osc_context *context)
 #define ACPI_GSB_ACCESS_ATTRIB_RAW_PROCESS	0x0000000F
 
 /* Enable _OST when all relevant hotplug operations are enabled */
-#if defined(CONFIG_ACPI_HOTPLUG_CPU) &&			\
+#if defined(CONFIG_ACPI_HOTPLUG_PRESENT_CPU) &&			\
 	defined(CONFIG_ACPI_HOTPLUG_MEMORY) &&		\
 	defined(CONFIG_ACPI_CONTAINER)
 #define ACPI_HOTPLUG_OST

index 6c70a004c198..2b9cb2667654 100644
@@ -531,7 +531,14 @@ int __weak arch_register_cpu(int cpu)
 {
 	return register_cpu(&per_cpu(cpu_devices, cpu), cpu);
 }
-#endif
+
+#ifdef CONFIG_HOTPLUG_CPU
+void __weak arch_unregister_cpu(int num)
+{
+	unregister_cpu(&per_cpu(cpu_devices, num));
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+#endif /* CONFIG_GENERIC_CPU_DEVICES */
 
 static void __init cpu_dev_register_generic(void)
 {

index 06e9bb4a633f..4343888c76d5 100644
@@ -244,6 +244,44 @@ static int acpi_scan_try_to_offline(struct acpi_device *device)
 	return 0;
 }
 
+static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used)
+{
+	struct acpi_scan_handler *handler = adev->handler;
+
+	acpi_dev_for_each_child_reverse(adev, acpi_bus_trim_one, NULL);
+
+	adev->flags.match_driver = false;
+	if (handler) {
+		if (handler->detach)
+			handler->detach(adev);
+
+		adev->handler = NULL;
+	} else {
+		device_release_driver(&adev->dev);
+	}
+	/*
+	 * Most likely, the device is going away, so put it into D3cold before
+	 * that.
+	 */
+	acpi_device_set_power(adev, ACPI_STATE_D3_COLD);
+	adev->flags.initialized = false;
+	acpi_device_clear_enumerated(adev);
+
+	return 0;
+}
+
+/**
+ * acpi_bus_trim - Detach scan handlers and drivers from ACPI device objects.
+ * @adev: Root of the ACPI namespace scope to walk.
+ *
+ * Must be called under acpi_scan_lock.
+ */
+void acpi_bus_trim(struct acpi_device *adev)
+{
+	acpi_bus_trim_one(adev, NULL);
+}
+EXPORT_SYMBOL_GPL(acpi_bus_trim);
+
 static int acpi_scan_hot_remove(struct acpi_device *device)
 {
 	acpi_handle handle = device->handle;

@@ -2507,44 +2545,6 @@ int acpi_bus_scan(acpi_handle handle)
 }
 EXPORT_SYMBOL(acpi_bus_scan);
 
-static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used)
-{
-	struct acpi_scan_handler *handler = adev->handler;
-
-	acpi_dev_for_each_child_reverse(adev, acpi_bus_trim_one, NULL);
-
-	adev->flags.match_driver = false;
-	if (handler) {
-		if (handler->detach)
-			handler->detach(adev);
-
-		adev->handler = NULL;
-	} else {
-		device_release_driver(&adev->dev);
-	}
-	/*
-	 * Most likely, the device is going away, so put it into D3cold before
-	 * that.
-	 */
-	acpi_device_set_power(adev, ACPI_STATE_D3_COLD);
-	adev->flags.initialized = false;
-	acpi_device_clear_enumerated(adev);
-
-	return 0;
-}
-
-/**
- * acpi_bus_trim - Detach scan handlers and drivers from ACPI device objects.
- * @adev: Root of the ACPI namespace scope to walk.
- *
- * Must be called under acpi_scan_lock.
- */
-void acpi_bus_trim(struct acpi_device *adev)
-{
-	acpi_bus_trim_one(adev, NULL);
-}
-EXPORT_SYMBOL_GPL(acpi_bus_trim);
-
 int acpi_bus_register_early_device(int type)
 {
 	struct acpi_device *device = NULL;

index c8e960ff0aca..26e3efb74614 100644
@@ -183,13 +183,15 @@ static void __init acpi_pcc_cpufreq_init(void) {}
 #endif /* CONFIG_X86 */
 
 /* Initialization */
-#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
-static int acpi_processor_hotadd_init(struct acpi_processor *pr)
+static int acpi_processor_make_present(struct acpi_processor *pr)
 {
 	unsigned long long sta;
 	acpi_status status;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
+		return -ENODEV;
+
 	if (invalid_phys_cpuid(pr->phys_id))
 		return -ENODEV;
 

@@ -223,12 +225,6 @@ static int acpi_processor_hotadd_init(struct acpi_processor *pr)
 	cpu_maps_update_done();
 	return ret;
 }
-#else
-static inline int acpi_processor_hotadd_init(struct acpi_processor *pr)
-{
-	return -ENODEV;
-}
-#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
 
 static int acpi_processor_get_info(struct acpi_device *device)
 {

@@ -335,7 +331,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
 	 *  because cpuid <-> apicid mapping is persistent now.
 	 */
 	if (invalid_logical_cpuid(pr->id) || !cpu_present(pr->id)) {
-		int ret = acpi_processor_hotadd_init(pr);
+		int ret = acpi_processor_make_present(pr);
 
 		if (ret)
 			return ret;

index 48ee36086577..3672312e15eb 100644
@@ -321,12 +321,10 @@ static inline int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
 }
 #endif
 
-#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 /* Arch dependent functions for cpu hotplug support */
 int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id,
 		 int *pcpu);
 int acpi_unmap_cpu(int cpu);
-#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
 
 #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
 int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);

index 26e3efb74614..b6f5005985c3 100644
@@ -459,7 +459,7 @@ static int acpi_processor_add(struct acpi_device *device,
 
 #ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 /* Removal */
-static void acpi_processor_remove(struct acpi_device *device)
+static void acpi_processor_post_eject(struct acpi_device *device)
 {
 	struct acpi_processor *pr;
 

@@ -627,7 +627,7 @@ static struct acpi_scan_handler processor_handler = {
 	.ids = processor_device_ids,
 	.attach = acpi_processor_add,
 #ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
-	.detach = acpi_processor_remove,
+	.post_eject = acpi_processor_post_eject,
 #endif
 	.hotplug = {
 		.enabled = true,

98 lines not on this page · raw message

index 254685085c82..1b7e1acf925b 100644
@@ -127,6 +127,7 @@ struct acpi_scan_handler {
 	bool (*match)(const char *idstr, const struct acpi_device_id **matchid);
 	int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
 	void (*detach)(struct acpi_device *dev);
+	void (*post_eject)(struct acpi_device *dev);
 	void (*bind)(struct device *phys_dev);
 	void (*unbind)(struct device *phys_dev);
 	struct acpi_hotplug_profile hotplug;

index b6f5005985c3..19fceb3ec4e2 100644
@@ -457,13 +457,12 @@ static int acpi_processor_add(struct acpi_device *device,
 	return result;
 }
 
-#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 /* Removal */
-static void acpi_processor_post_eject(struct acpi_device *device)
+static void acpi_processor_make_not_present(struct acpi_device *device)
 {
 	struct acpi_processor *pr;
 
-	if (!device || !acpi_driver_data(device))
+	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
 		return;
 
 	pr = acpi_driver_data(device);

@@ -501,7 +500,29 @@ static void acpi_processor_post_eject(struct acpi_device *device)
 	free_cpumask_var(pr->throttling.shared_cpu_map);
 	kfree(pr);
 }
-#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
+
+static void acpi_processor_post_eject(struct acpi_device *device)
+{
+	struct acpi_processor *pr;
+	unsigned long long sta;
+	acpi_status status;
+
+	if (!device)
+		return;
+
+	pr = acpi_driver_data(device);
+	if (!pr || pr->id >= nr_cpu_ids || invalid_phys_cpuid(pr->phys_id))
+		return;
+
+	status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta);
+	if (ACPI_FAILURE(status))
+		return;
+
+	if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_PRESENT)) {
+		acpi_processor_make_not_present(device);
+		return;
+	}
+}
 
 #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC
 bool __init processor_physically_present(acpi_handle handle)

@@ -626,9 +647,7 @@ static const struct acpi_device_id processor_device_ids[] = {
 static struct acpi_scan_handler processor_handler = {
 	.ids = processor_device_ids,
 	.attach = acpi_processor_add,
-#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
 	.post_eject = acpi_processor_post_eject,
-#endif
 	.hotplug = {
 		.enabled = true,
 	},

index 19fceb3ec4e2..b7a94c1348b0 100644
@@ -189,8 +189,10 @@ static int acpi_processor_make_present(struct acpi_processor *pr)
 	acpi_status status;
 	int ret;
 
-	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
+	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) {
+		pr_err_once("Changing CPU present bit is not supported\n");
 		return -ENODEV;
+	}
 
 	if (invalid_phys_cpuid(pr->phys_id))
 		return -ENODEV;

@@ -462,8 +464,10 @@ static void acpi_processor_make_not_present(struct acpi_device *device)
 {
 	struct acpi_processor *pr;
 
-	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
+	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) {
+		pr_err_once("Changing CPU present bit is not supported");
 		return;
+	}
 
 	pr = acpi_driver_data(device);
 	if (pr->id >= nr_cpu_ids)

index bf58351beac1..b595edbfdbcd 100644
@@ -19,13 +19,4 @@ int arch_register_cpu(int cpu)
 	return register_cpu(c, cpu);
 }
 EXPORT_SYMBOL(arch_register_cpu);
-
-void arch_unregister_cpu(int cpu)
-{
-	struct cpu *c = &per_cpu(cpu_devices, cpu);
-
-	c->hotpluggable = 0;
-	unregister_cpu(c);
-}
-EXPORT_SYMBOL(arch_unregister_cpu);
 #endif

index 6792a1f83f2a..bc9a6656fc0c 100644
@@ -119,6 +119,17 @@ static inline u32 get_acpi_id_for_cpu(unsigned int cpu)
 	return	acpi_cpu_get_madt_gicc(cpu)->uid;
 }
 
+static inline int get_cpu_for_acpi_id(u32 uid)
+{
+	int cpu;
+
+	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
+		if (uid == get_acpi_id_for_cpu(cpu))
+			return cpu;
+
+	return -EINVAL;
+}
+
 static inline void arch_fix_phys_package_id(int num, u32 slot) { }
 void __init acpi_init_cpus(void);
 int apei_claim_sea(struct pt_regs *regs);

index e51535a5f939..0c036a9a3c33 100644
@@ -34,17 +34,6 @@ int __init acpi_numa_get_nid(unsigned int cpu)
 	return acpi_early_node_map[cpu];
 }
 
-static inline int get_cpu_for_acpi_id(u32 uid)
-{
-	int cpu;
-
-	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
-		if (uid == get_acpi_id_for_cpu(cpu))
-			return cpu;
-
-	return -EINVAL;
-}
-
 static int __init acpi_parse_gicc_pxm(union acpi_subtable_headers *header,
 				      const unsigned long end)
 {

index 3751ae69432f..c433a079d8e1 100644
@@ -1046,6 +1046,7 @@ struct acpi_madt_generic_interrupt {
 /* ACPI_MADT_ENABLED                    (1)      Processor is usable if set */
 #define ACPI_MADT_PERFORMANCE_IRQ_MODE  (1<<1)	/* 01: Performance Interrupt Mode */
 #define ACPI_MADT_VGIC_IRQ_MODE         (1<<2)	/* 02: VGIC Maintenance Interrupt mode */
+#define ACPI_MADT_GICC_CPU_CAPABLE      (1<<3)	/* 03: CPU is online capable */
 
 /* 12: Generic Distributor (ACPI 5.0 + ACPI 6.0 changes) */
 

index d50d9414f471..e787e7bbb5a2 100644
@@ -2428,21 +2428,15 @@ static int __init gic_acpi_match_gicc(union acpi_subtable_headers *header,
 
 	/*
 	 * If GICC is enabled and has valid gicr base address, then it means
-	 * GICR base is presented via GICC
+	 * GICR base is presented via GICC. The redistributor is only known to
+	 * be accessible if the GICC is marked as enabled. If this bit is not
+	 * set, we'd need to add the redistributor at runtime, which isn't
+	 * supported.
 	 */
-	if (acpi_gicc_is_usable(gicc) && gicc->gicr_base_address) {
+	if (gicc->flags & ACPI_MADT_ENABLED && gicc->gicr_base_address)
 		acpi_data.enabled_rdists++;
-		return 0;
-	}
 
-	/*
-	 * It's perfectly valid firmware can pass disabled GICC entry, driver
-	 * should not treat as errors, skip the entry instead of probe fail.
-	 */
-	if (!acpi_gicc_is_usable(gicc))
-		return 0;
-
-	return -ENODEV;
+	return 0;
 }
 
 static int __init gic_acpi_count_gicr_regions(void)

index e787e7bbb5a2..8a89b853a5b9 100644
@@ -2378,11 +2378,25 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
 				(struct acpi_madt_generic_interrupt *)header;
 	u32 reg = readl_relaxed(acpi_data.dist_base + GICD_PIDR2) & GIC_PIDR2_ARCH_MASK;
 	u32 size = reg == GIC_PIDR2_ARCH_GICv4 ? SZ_64K * 4 : SZ_64K * 2;
+	int cpu = get_cpu_for_acpi_id(gicc->uid);
 	void __iomem *redist_base;
 
 	if (!acpi_gicc_is_usable(gicc))
 		return 0;
 
+	/*
+	 * Capable but disabled CPUs can be brought online later. What about
+	 * the redistributor? ACPI doesn't want to say!
+	 * Virtual hotplug systems can use the MADT's "always-on" GICR entries.
+	 * Otherwise, prevent such CPUs from being brought online.
+	 */
+	if (!(gicc->flags & ACPI_MADT_ENABLED)) {
+		pr_warn_once("CPU %u's redistributor is inaccessible: this CPU can't be brought online\n", cpu);
+		set_cpu_present(cpu, false);
+		set_cpu_possible(cpu, false);
+		return 0;
+	}
+
 	redist_base = ioremap(gicc->gicr_base_address, size);
 	if (!redist_base)
 		return -ENOMEM;

index 3672312e15eb..ed1ef5d8687f 100644
@@ -258,7 +258,7 @@ void acpi_table_print_madt_entry (struct acpi_subtable_header *madt);
 
 static inline bool acpi_gicc_is_usable(struct acpi_madt_generic_interrupt *gicc)
 {
-	return gicc->flags & ACPI_MADT_ENABLED;
+	return gicc->flags & (ACPI_MADT_ENABLED | ACPI_MADT_GICC_CPU_CAPABLE);
 }
 
 /* the following numa functions are architecture-dependent */

index 29a8e444db83..4fcc0cdd757b 100644
@@ -40,7 +40,7 @@ static int cpu_psci_cpu_boot(unsigned int cpu)
 {
 	phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry);
 	int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry);
-	if (err)
+	if (err && err != -EPROBE_DEFER)
 		pr_err("failed to boot CPU%d (%d)\n", cpu, err);
 
 	return err;

index 8c8f55721786..68ec7fbe166f 100644
@@ -124,7 +124,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 	/* Now bring the CPU into our world */
 	ret = boot_secondary(cpu, idle);
 	if (ret) {
-		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
+		if (ret != -EPERM)
+			pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 		return ret;
 	}
 

index d9629ff87861..ee82e7880d8c 100644
@@ -218,6 +218,8 @@ static int __psci_cpu_on(u32 fn, unsigned long cpuid, unsigned long entry_point)
 	int err;
 
 	err = invoke_psci_fn(fn, cpuid, entry_point, 0);
+	if (err == PSCI_RET_DENIED)
+		return -EPERM;
 	return psci_to_linux_errno(err);
 }
 

index b7a94c1348b0..5dabb426481f 100644
@@ -228,6 +228,32 @@ static int acpi_processor_make_present(struct acpi_processor *pr)
 	return ret;
 }
 
+static int acpi_processor_make_enabled(struct acpi_processor *pr)
+{
+	unsigned long long sta;
+	acpi_status status;
+	bool present, enabled;
+
+	if (!acpi_has_method(pr->handle, "_STA"))
+		return arch_register_cpu(pr->id);
+
+	status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	present = sta & ACPI_STA_DEVICE_PRESENT;
+	enabled = sta & ACPI_STA_DEVICE_ENABLED;
+
+	if (cpu_online(pr->id) && (!present || !enabled)) {
+		pr_err_once(FW_BUG "CPU %u is online, but described as not present or disabled!\n", pr->id);
+		add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+	} else if (!present || !enabled) {
+		return -ENODEV;
+	}
+
+	return arch_register_cpu(pr->id);
+}
+
 static int acpi_processor_get_info(struct acpi_device *device)
 {
 	union acpi_object object = { 0 };

@@ -318,7 +344,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
 	 */
 	if (!invalid_logical_cpuid(pr->id) && cpu_present(pr->id) &&
 	    !get_cpu_device(pr->id)) {
-		int ret = arch_register_cpu(pr->id);
+		int ret = acpi_processor_make_enabled(pr);
 
 		if (ret)
 			return ret;

@@ -526,6 +552,9 @@ static void acpi_processor_post_eject(struct acpi_device *device)
 		acpi_processor_make_not_present(device);
 		return;
 	}
+
+	if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_ENABLED))
+		arch_unregister_cpu(pr->id);
 }
 
 #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC

index 5dabb426481f..539412ff59a1 100644
@@ -182,6 +182,18 @@ static void __init acpi_pcc_cpufreq_init(void)
 static void __init acpi_pcc_cpufreq_init(void) {}
 #endif /* CONFIG_X86 */
 
+static bool acpi_processor_hotplug_present_supported(void)
+{
+	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
+		return false;
+
+	/* x86 systems pre-date the _OSC bit */
+	if (IS_ENABLED(CONFIG_ACPI_HOTPLUG_IGNORE_OSC))
+		return true;
+
+	return osc_sb_hotplug_present_support_acked;
+}
+
 /* Initialization */
 static int acpi_processor_make_present(struct acpi_processor *pr)
 {

@@ -189,7 +201,7 @@ static int acpi_processor_make_present(struct acpi_processor *pr)
 	acpi_status status;
 	int ret;
 
-	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU)) {
+	if (!acpi_processor_hotplug_present_supported()) {
 		pr_err_once("Changing CPU present bit is not supported\n");
 		return -ENODEV;
 	}

index a4aa53b7e2bb..b42f17bfbb09 100644
@@ -298,6 +298,13 @@ EXPORT_SYMBOL_GPL(osc_sb_native_usb4_support_confirmed);
 
 bool osc_sb_cppc2_support_acked;
 
+/*
+ * ACPI 6.? Proposed Operating System Capabilities for modifying CPU
+ * present/enable.
+ */
+bool osc_sb_hotplug_enabled_support_acked;
+bool osc_sb_hotplug_present_support_acked;
+
 static u8 sb_uuid_str[] = "0811B06E-4A27-44F9-8D60-3CBBC22E7B48";
 static void acpi_bus_osc_negotiate_platform_control(void)
 {

@@ -346,6 +353,11 @@ static void acpi_bus_osc_negotiate_platform_control(void)
 
 	if (!ghes_disable)
 		capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_APEI_SUPPORT;
+
+	capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_HOTPLUG_ENABLED_SUPPORT;
+	if (IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
+		capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_HOTPLUG_PRESENT_SUPPORT;
+
 	if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle)))
 		return;
 

@@ -383,6 +395,10 @@ static void acpi_bus_osc_negotiate_platform_control(void)
 			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_NATIVE_USB4_SUPPORT;
 		osc_cpc_flexible_adr_space_confirmed =
 			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_CPC_FLEXIBLE_ADR_SPACE;
+		osc_sb_hotplug_enabled_support_acked =
+			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_HOTPLUG_ENABLED_SUPPORT;
+		osc_sb_hotplug_present_support_acked =
+			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_HOTPLUG_PRESENT_SUPPORT;
 	}
 
 	kfree(context.ret.pointer);

index ed1ef5d8687f..53515ff1318f 100644
@@ -579,12 +579,16 @@ acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context);
 #define OSC_SB_NATIVE_USB4_SUPPORT		0x00040000
 #define OSC_SB_PRM_SUPPORT			0x00200000
 #define OSC_SB_FFH_OPR_SUPPORT			0x00400000
+#define OSC_SB_HOTPLUG_ENABLED_SUPPORT		0x00800000
+#define OSC_SB_HOTPLUG_PRESENT_SUPPORT		0x01000000
 
 extern bool osc_sb_apei_support_acked;
 extern bool osc_pc_lpi_support_confirmed;
 extern bool osc_sb_native_usb4_support_confirmed;
 extern bool osc_sb_cppc2_support_acked;
 extern bool osc_cpc_flexible_adr_space_confirmed;
+extern bool osc_sb_hotplug_enabled_support_acked;
+extern bool osc_sb_hotplug_present_support_acked;
 
 /* USB4 Capabilities */
 #define OSC_USB_USB3_TUNNELING			0x00000001

index 2b9cb2667654..f8bf1d4c7d71 100644
@@ -95,6 +95,7 @@ void unregister_cpu(struct cpu *cpu)
 {
 	int logical_cpu = cpu->dev.id;
 
+	set_cpu_enabled(logical_cpu, false);
 	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
 
 	device_unregister(&cpu->dev);

@@ -273,6 +274,13 @@ static ssize_t print_cpus_offline(struct device *dev,
 }
 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
 
+static ssize_t print_cpus_enabled(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_enabled_mask));
+}
+static DEVICE_ATTR(enabled, 0444, print_cpus_enabled, NULL);
+
 static ssize_t print_cpus_isolated(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {

@@ -413,6 +421,7 @@ int register_cpu(struct cpu *cpu, int num)
 	register_cpu_under_node(num, cpu_to_node(num));
 	dev_pm_qos_expose_latency_limit(&cpu->dev,
 					PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
+	set_cpu_enabled(num, true);
 
 	return 0;
 }

@@ -494,6 +503,7 @@ static struct attribute *cpu_root_attrs[] = {
 	&cpu_attrs[2].attr.attr,
 	&dev_attr_kernel_max.attr,
 	&dev_attr_offline.attr,
+	&dev_attr_enabled.attr,
 	&dev_attr_isolated.attr,
 #ifdef CONFIG_NO_HZ_FULL
 	&dev_attr_nohz_full.attr,

index f10fb87d49db..a29ee03f13ff 100644
@@ -92,6 +92,7 @@ static inline void set_nr_cpu_ids(unsigned int nr)
  *
  *     cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
  *     cpu_present_mask - has bit 'cpu' set iff cpu is populated
+ *     cpu_enabled_mask  - has bit 'cpu' set iff cpu can be brought online
  *     cpu_online_mask  - has bit 'cpu' set iff cpu available to scheduler
  *     cpu_active_mask  - has bit 'cpu' set iff cpu available to migration
  *

@@ -124,11 +125,13 @@ static inline void set_nr_cpu_ids(unsigned int nr)
 
 extern struct cpumask __cpu_possible_mask;
 extern struct cpumask __cpu_online_mask;
+extern struct cpumask __cpu_enabled_mask;
 extern struct cpumask __cpu_present_mask;
 extern struct cpumask __cpu_active_mask;
 extern struct cpumask __cpu_dying_mask;
 #define cpu_possible_mask ((const struct cpumask *)&__cpu_possible_mask)
 #define cpu_online_mask   ((const struct cpumask *)&__cpu_online_mask)
+#define cpu_enabled_mask   ((const struct cpumask *)&__cpu_enabled_mask)
 #define cpu_present_mask  ((const struct cpumask *)&__cpu_present_mask)
 #define cpu_active_mask   ((const struct cpumask *)&__cpu_active_mask)
 #define cpu_dying_mask    ((const struct cpumask *)&__cpu_dying_mask)

@@ -973,6 +976,7 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
 #else
 #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
 #define for_each_online_cpu(cpu)   for_each_cpu((cpu), cpu_online_mask)
+#define for_each_enabled_cpu(cpu)   for_each_cpu((cpu), cpu_enabled_mask)
 #define for_each_present_cpu(cpu)  for_each_cpu((cpu), cpu_present_mask)
 #endif
 

@@ -995,6 +999,15 @@ set_cpu_possible(unsigned int cpu, bool possible)
 		cpumask_clear_cpu(cpu, &__cpu_possible_mask);
 }
 
+static inline void
+set_cpu_enabled(unsigned int cpu, bool can_be_onlined)
+{
+	if (can_be_onlined)
+		cpumask_set_cpu(cpu, &__cpu_enabled_mask);
+	else
+		cpumask_clear_cpu(cpu, &__cpu_enabled_mask);
+}
+
 static inline void
 set_cpu_present(unsigned int cpu, bool present)
 {

@@ -1074,6 +1087,7 @@ static __always_inline unsigned int num_online_cpus(void)
 	return raw_atomic_read(&__num_online_cpus);
 }
 #define num_possible_cpus()	cpumask_weight(cpu_possible_mask)
+#define num_enabled_cpus()	cpumask_weight(cpu_enabled_mask)
 #define num_present_cpus()	cpumask_weight(cpu_present_mask)
 #define num_active_cpus()	cpumask_weight(cpu_active_mask)
 

@@ -1082,6 +1096,11 @@ static inline bool cpu_online(unsigned int cpu)
 	return cpumask_test_cpu(cpu, cpu_online_mask);
 }
 
+static inline bool cpu_enabled(unsigned int cpu)
+{
+	return cpumask_test_cpu(cpu, cpu_enabled_mask);
+}
+
 static inline bool cpu_possible(unsigned int cpu)
 {
 	return cpumask_test_cpu(cpu, cpu_possible_mask);

@@ -1106,6 +1125,7 @@ static inline bool cpu_dying(unsigned int cpu)
 
 #define num_online_cpus()	1U
 #define num_possible_cpus()	1U
+#define num_enabled_cpus()	1U
 #define num_present_cpus()	1U
 #define num_active_cpus()	1U
 

@@ -1119,6 +1139,11 @@ static inline bool cpu_possible(unsigned int cpu)
 	return cpu == 0;
 }
 
+static inline bool cpu_enabled(unsigned int cpu)
+{
+	return cpu == 0;
+}
+
 static inline bool cpu_present(unsigned int cpu)
 {
 	return cpu == 0;

index 6de7c6bb74ee..2201a6a449b5 100644
@@ -3101,6 +3101,9 @@ EXPORT_SYMBOL(__cpu_possible_mask);
 struct cpumask __cpu_online_mask __read_mostly;
 EXPORT_SYMBOL(__cpu_online_mask);
 
+struct cpumask __cpu_enabled_mask __read_mostly;
+EXPORT_SYMBOL(__cpu_enabled_mask);
+
 struct cpumask __cpu_present_mask __read_mostly;
 EXPORT_SYMBOL(__cpu_present_mask);