diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 98722773391d..40a3d3642f3a 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -138,7 +138,6 @@ extern void lapic_shutdown(void);
 extern void sync_Arb_IDs(void);
 extern void init_bsp_APIC(void);
 extern void apic_intr_mode_init(void);
-extern void setup_local_APIC(void);
 extern void init_apic_mappings(void);
 void register_lapic_address(unsigned long address);
 extern void setup_boot_APIC_clock(void);
@@ -183,6 +182,7 @@ static inline void disable_local_APIC(void) { }
 # define setup_boot_APIC_clock x86_init_noop
 # define setup_secondary_APIC_clock x86_init_noop
 static inline void lapic_update_tsc_freq(void) { }
+static inline void init_bsp_APIC(void) { }
 static inline void apic_intr_mode_init(void) { }
 static inline void lapic_assign_system_vectors(void) { }
 static inline void lapic_assign_legacy_vector(unsigned int i, bool r) { }
@@ -304,12 +304,6 @@ struct apic {
 	u32	irq_delivery_mode;
 	u32	irq_dest_mode;
 
-	/* Functions and data related to vector allocation */
-	void	(*vector_allocation_domain)(int cpu, struct cpumask *retmask,
-					    const struct cpumask *mask);
-	int	(*cpu_mask_to_apicid)(const struct cpumask *cpumask,
-				      struct irq_data *irqdata,
-				      unsigned int *apicid);
 	u32	(*calc_dest_apicid)(unsigned int cpu);
 
 	/* ICR related functions */
@@ -499,17 +493,7 @@ extern void default_setup_apic_routing(void);
 extern u32 apic_default_calc_apicid(unsigned int cpu);
 extern u32 apic_flat_calc_apicid(unsigned int cpu);
 
-extern int flat_cpu_mask_to_apicid(const struct cpumask *cpumask,
-				   struct irq_data *irqdata,
-				   unsigned int *apicid);
-extern int default_cpu_mask_to_apicid(const struct cpumask *cpumask,
-				      struct irq_data *irqdata,
-				      unsigned int *apicid);
 extern bool default_check_apicid_used(physid_mask_t *map, int apicid);
-extern void flat_vector_allocation_domain(int cpu, struct cpumask *retmask,
-				   const struct cpumask *mask);
-extern void default_vector_allocation_domain(int cpu, struct cpumask *retmask,
-				      const struct cpumask *mask);
 extern void default_ioapic_phys_id_map(physid_mask_t *phys_map, physid_mask_t *retmap);
 extern int default_cpu_present_to_apicid(int mps_cpu);
 extern int default_check_phys_apicid_present(int phys_apicid);
diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index a8834dd546cd..fd20a2334885 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -183,16 +183,17 @@ extern void disable_ioapic_support(void);
 
 extern void __init io_apic_init_mappings(void);
 extern unsigned int native_io_apic_read(unsigned int apic, unsigned int reg);
-extern void native_disable_io_apic(void);
+extern void native_restore_boot_irq_mode(void);
 
 static inline unsigned int io_apic_read(unsigned int apic, unsigned int reg)
 {
-	return x86_io_apic_ops.read(apic, reg);
+	return x86_apic_ops.io_apic_read(apic, reg);
 }
 
 extern void setup_IO_APIC(void);
 extern void enable_IO_APIC(void);
-extern void disable_IO_APIC(void);
+extern void clear_IO_APIC(void);
+extern void restore_boot_irq_mode(void);
 extern int IO_APIC_get_PCI_irq_vector(int bus, int devfn, int pin);
 extern void print_IO_APICs(void);
 #else  /* !CONFIG_X86_IO_APIC */
@@ -228,10 +229,11 @@ static inline void mp_save_irq(struct mpc_intsrc *m) { }
 static inline void disable_ioapic_support(void) { }
 static inline void io_apic_init_mappings(void) { }
 #define native_io_apic_read		NULL
-#define native_disable_io_apic		NULL
+#define native_restore_boot_irq_mode	NULL
 
 static inline void setup_IO_APIC(void) { }
 static inline void enable_IO_APIC(void) { }
+static inline void restore_boot_irq_mode(void) { }
 
 #endif
 
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index a4189762b266..f75bff8f9d82 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -177,16 +177,6 @@ static inline int wbinvd_on_all_cpus(void)
 extern unsigned disabled_cpus;
 
 #ifdef CONFIG_X86_LOCAL_APIC
-
-#ifndef CONFIG_X86_64
-static inline int logical_smp_processor_id(void)
-{
-	/* we don't want to mark this access volatile - bad code generation */
-	return GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
-}
-
-#endif
-
 extern int hard_smp_processor_id(void);
 
 #else /* CONFIG_X86_LOCAL_APIC */
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index fc2f082ac635..88306054bd98 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -274,16 +274,16 @@ struct x86_msi_ops {
 	void (*restore_msi_irqs)(struct pci_dev *dev);
 };
 
-struct x86_io_apic_ops {
-	unsigned int	(*read)   (unsigned int apic, unsigned int reg);
-	void		(*disable)(void);
+struct x86_apic_ops {
+	unsigned int	(*io_apic_read)   (unsigned int apic, unsigned int reg);
+	void		(*restore)(void);
 };
 
 extern struct x86_init_ops x86_init;
 extern struct x86_cpuinit_ops x86_cpuinit;
 extern struct x86_platform_ops x86_platform;
 extern struct x86_msi_ops x86_msi;
-extern struct x86_io_apic_ops x86_io_apic_ops;
+extern struct x86_apic_ops x86_apic_ops;
 
 extern void x86_early_init_platform_quirks(void);
 extern void x86_init_noop(void);
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index b203af0855b5..2aabd4cb0e3f 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1408,22 +1408,69 @@ static void lapic_setup_esr(void)
 			oldvalue, value);
 }
 
+static void apic_pending_intr_clear(void)
+{
+	long long max_loops = cpu_khz ? cpu_khz : 1000000;
+	unsigned long long tsc = 0, ntsc;
+	unsigned int queued;
+	unsigned long value;
+	int i, j, acked = 0;
+
+	if (boot_cpu_has(X86_FEATURE_TSC))
+		tsc = rdtsc();
+	/*
+	 * After a crash, we no longer service the interrupts and a pending
+	 * interrupt from previous kernel might still have ISR bit set.
+	 *
+	 * Most probably by now CPU has serviced that pending interrupt and
+	 * it might not have done the ack_APIC_irq() because it thought,
+	 * interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
+	 * does not clear the ISR bit and cpu thinks it has already serivced
+	 * the interrupt. Hence a vector might get locked. It was noticed
+	 * for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
+	 */
+	do {
+		queued = 0;
+		for (i = APIC_ISR_NR - 1; i >= 0; i--)
+			queued |= apic_read(APIC_IRR + i*0x10);
+
+		for (i = APIC_ISR_NR - 1; i >= 0; i--) {
+			value = apic_read(APIC_ISR + i*0x10);
+			for_each_set_bit(j, &value, 32) {
+				ack_APIC_irq();
+				acked++;
+			}
+		}
+		if (acked > 256) {
+			pr_err("LAPIC pending interrupts after %d EOI\n", acked);
+			break;
+		}
+		if (queued) {
+			if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
+				ntsc = rdtsc();
+				max_loops = (cpu_khz << 10) - (ntsc - tsc);
+			} else {
+				max_loops--;
+			}
+		}
+	} while (queued && max_loops > 0);
+	WARN_ON(max_loops <= 0);
+}
+
 /**
  * setup_local_APIC - setup the local APIC
  *
  * Used to setup local APIC while initializing BSP or bringing up APs.
  * Always called with preemption disabled.
  */
-void setup_local_APIC(void)
+static void setup_local_APIC(void)
 {
 	int cpu = smp_processor_id();
-	unsigned int value, queued;
-	int i, j, acked = 0;
-	unsigned long long tsc = 0, ntsc;
-	long long max_loops = cpu_khz ? cpu_khz : 1000000;
+	unsigned int value;
+#ifdef CONFIG_X86_32
+	int logical_apicid, ldr_apicid;
+#endif
 
-	if (boot_cpu_has(X86_FEATURE_TSC))
-		tsc = rdtsc();
 
 	if (disable_apic) {
 		disable_ioapic_support();
@@ -1460,11 +1507,11 @@ void setup_local_APIC(void)
 	 * initialized during get_smp_config(), make sure it matches the
 	 * actual value.
 	 */
-	i = early_per_cpu(x86_cpu_to_logical_apicid, cpu);
-	WARN_ON(i != BAD_APICID && i != logical_smp_processor_id());
+	logical_apicid = early_per_cpu(x86_cpu_to_logical_apicid, cpu);
+	ldr_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
+	WARN_ON(logical_apicid != BAD_APICID && logical_apicid != ldr_apicid);
 	/* always use the value from LDR */
-	early_per_cpu(x86_cpu_to_logical_apicid, cpu) =
-		logical_smp_processor_id();
+	early_per_cpu(x86_cpu_to_logical_apicid, cpu) = ldr_apicid;
 #endif
 
 	/*
@@ -1475,45 +1522,7 @@ void setup_local_APIC(void)
 	value &= ~APIC_TPRI_MASK;
 	apic_write(APIC_TASKPRI, value);
 
-	/*
-	 * After a crash, we no longer service the interrupts and a pending
-	 * interrupt from previous kernel might still have ISR bit set.
-	 *
-	 * Most probably by now CPU has serviced that pending interrupt and
-	 * it might not have done the ack_APIC_irq() because it thought,
-	 * interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
-	 * does not clear the ISR bit and cpu thinks it has already serivced
-	 * the interrupt. Hence a vector might get locked. It was noticed
-	 * for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
-	 */
-	do {
-		queued = 0;
-		for (i = APIC_ISR_NR - 1; i >= 0; i--)
-			queued |= apic_read(APIC_IRR + i*0x10);
-
-		for (i = APIC_ISR_NR - 1; i >= 0; i--) {
-			value = apic_read(APIC_ISR + i*0x10);
-			for (j = 31; j >= 0; j--) {
-				if (value & (1<<j)) {
-					ack_APIC_irq();
-					acked++;
-				}
-			}
-		}
-		if (acked > 256) {
-			printk(KERN_ERR "LAPIC pending interrupts after %d EOI\n",
-			       acked);
-			break;
-		}
-		if (queued) {
-			if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
-				ntsc = rdtsc();
-				max_loops = (cpu_khz << 10) - (ntsc - tsc);
-			} else
-				max_loops--;
-		}
-	} while (queued && max_loops > 0);
-	WARN_ON(max_loops <= 0);
+	apic_pending_intr_clear();
 
 	/*
 	 * Now that we are all set up, enable the APIC
@@ -1570,7 +1579,7 @@ void setup_local_APIC(void)
 	 * TODO: set up through-local-APIC from through-I/O-APIC? --macro
 	 */
 	value = apic_read(APIC_LVT0) & APIC_LVT_MASKED;
-	if (!cpu && (pic_mode || !value)) {
+	if (!cpu && (pic_mode || !value || skip_ioapic_setup)) {
 		value = APIC_DM_EXTINT;
 		apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", cpu);
 	} else {
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 7c5538769f7e..7553819c74c3 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -587,7 +587,7 @@ static void clear_IO_APIC_pin(unsigned int apic, unsigned int pin)
 		       mpc_ioapic_id(apic), pin);
 }
 
-static void clear_IO_APIC (void)
+void clear_IO_APIC (void)
 {
 	int apic, pin;
 
@@ -1410,7 +1410,7 @@ void __init enable_IO_APIC(void)
 	clear_IO_APIC();
 }
 
-void native_disable_io_apic(void)
+void native_restore_boot_irq_mode(void)
 {
 	/*
 	 * If the i8259 is routed through an IOAPIC
@@ -1438,20 +1438,12 @@ void native_disable_io_apic(void)
 		disconnect_bsp_APIC(ioapic_i8259.pin != -1);
 }
 
-/*
- * Not an __init, needed by the reboot code
- */
-void disable_IO_APIC(void)
+void restore_boot_irq_mode(void)
 {
-	/*
-	 * Clear the IO-APIC before rebooting:
-	 */
-	clear_IO_APIC();
-
 	if (!nr_legacy_irqs())
 		return;
 
-	x86_io_apic_ops.disable();
+	x86_apic_ops.restore();
 }
 
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index f8d9d69994e6..e2829bf40e4a 100644
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -14,7 +14,7 @@ int x2apic_phys;
 
 static struct apic apic_x2apic_phys;
 
-static int set_x2apic_phys_mode(char *arg)
+static int __init set_x2apic_phys_mode(char *arg)
 {
 	x2apic_phys = 1;
 	return 0;
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 10e74d4778a1..1f6680427ff0 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -199,9 +199,10 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
 #ifdef CONFIG_X86_IO_APIC
 	/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
 	ioapic_zap_locks();
-	disable_IO_APIC();
+	clear_IO_APIC();
 #endif
 	lapic_shutdown();
+	restore_boot_irq_mode();
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
 #endif
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index a539410c4ea9..772196c1b8c4 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -61,9 +61,14 @@ void __init init_ISA_irqs(void)
 	struct irq_chip *chip = legacy_pic->chip;
 	int i;
 
-#if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)
+	/*
+	 * Try to set up the through-local-APIC virtual wire mode earlier.
+	 *
+	 * On some 32-bit UP machines, whose APIC has been disabled by BIOS
+	 * and then got re-enabled by "lapic", it hangs at boot time without this.
+	 */
 	init_bsp_APIC();
-#endif
+
 	legacy_pic->init(0);
 
 	for (i = 0; i < nr_legacy_irqs(); i++)
diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index edfede768688..60cdec6628b0 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -195,11 +195,11 @@ void machine_kexec(struct kimage *image)
 		/*
 		 * We need to put APICs in legacy mode so that we can
 		 * get timer interrupts in second kernel. kexec/kdump
-		 * paths already have calls to disable_IO_APIC() in
-		 * one form or other. kexec jump path also need
-		 * one.
+		 * paths already have calls to restore_boot_irq_mode()
+		 * in one form or other. kexec jump path also need one.
 		 */
-		disable_IO_APIC();
+		clear_IO_APIC();
+		restore_boot_irq_mode();
 #endif
 	}
 
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 3b7427aa7d85..faeea0b5cbd0 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -293,11 +293,11 @@ void machine_kexec(struct kimage *image)
 		/*
 		 * We need to put APICs in legacy mode so that we can
 		 * get timer interrupts in second kernel. kexec/kdump
-		 * paths already have calls to disable_IO_APIC() in
-		 * one form or other. kexec jump path also need
-		 * one.
+		 * paths already have calls to restore_boot_irq_mode()
+		 * in one form or other. kexec jump path also need one.
 		 */
-		disable_IO_APIC();
+		clear_IO_APIC();
+		restore_boot_irq_mode();
 #endif
 	}
 
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 2126b9d27c34..725624b6c0c0 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -666,7 +666,7 @@ void native_machine_shutdown(void)
 	 * Even without the erratum, it still makes sense to quiet IO APIC
 	 * before disabling Local APIC.
 	 */
-	disable_IO_APIC();
+	clear_IO_APIC();
 #endif
 
 #ifdef CONFIG_SMP
@@ -680,6 +680,7 @@ void native_machine_shutdown(void)
 #endif
 
 	lapic_shutdown();
+	restore_boot_irq_mode();
 
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 1151ccd72ce9..2bccd03bd654 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -146,7 +146,7 @@ void arch_restore_msi_irqs(struct pci_dev *dev)
 }
 #endif
 
-struct x86_io_apic_ops x86_io_apic_ops __ro_after_init = {
-	.read			= native_io_apic_read,
-	.disable		= native_disable_io_apic,
+struct x86_apic_ops x86_apic_ops __ro_after_init = {
+	.io_apic_read	= native_io_apic_read,
+	.restore	= native_restore_boot_irq_mode,
 };
diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
index de58533d3664..2163888497d3 100644
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -215,7 +215,7 @@ static void __init xen_apic_check(void)
 }
 void __init xen_init_apic(void)
 {
-	x86_io_apic_ops.read = xen_io_apic_read;
+	x86_apic_ops.io_apic_read = xen_io_apic_read;
 	/* On PV guests the APIC CPUID bit is disabled so none of the
 	 * routines end up executing. */
 	if (!xen_initial_domain())
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 49721b4e1975..496deee3ae3a 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -27,7 +27,7 @@ int disable_irq_post = 0;
 static int disable_irq_remap;
 static struct irq_remap_ops *remap_ops;
 
-static void irq_remapping_disable_io_apic(void)
+static void irq_remapping_restore_boot_irq_mode(void)
 {
 	/*
 	 * With interrupt-remapping, for now we will use virtual wire A
@@ -42,7 +42,7 @@ static void irq_remapping_disable_io_apic(void)
 
 static void __init irq_remapping_modify_x86_ops(void)
 {
-	x86_io_apic_ops.disable		= irq_remapping_disable_io_apic;
+	x86_apic_ops.restore = irq_remapping_restore_boot_irq_mode;
 }
 
 static __init int setup_nointremap(char *str)