Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 APIC updates from Ingo Molnar:
 "Continued fallout of the conversion of the x86 IRQ code to the
  hierarchical irqdomain framework: more cleanups, simplifications,
  memory allocation behavior enhancements, mainly in the interrupt
  remapping and APIC code"

* 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
  x86, init: Fix UP boot regression on x86_64
  iommu/amd: Fix irq remapping detection logic
  x86/acpi: Make acpi_[un]register_gsi_ioapic() depend on CONFIG_X86_LOCAL_APIC
  x86: Consolidate boot cpu timer setup
  x86/apic: Reuse apic_bsp_setup() for UP APIC setup
  x86/smpboot: Sanitize uniprocessor init
  x86/smpboot: Move apic init code to apic.c
  init: Get rid of x86isms
  x86/apic: Move apic_init_uniprocessor code
  x86/smpboot: Cleanup ioapic handling
  x86/apic: Sanitize ioapic handling
  x86/ioapic: Add proper checks to setp/enable_IO_APIC()
  x86/ioapic: Provide stub functions for IOAPIC%3Dn
  x86/smpboot: Move smpboot inlines to code
  x86/x2apic: Use state information for disable
  x86/x2apic: Split enable and setup function
  x86/x2apic: Disable x2apic from nox2apic setup
  x86/x2apic: Add proper state tracking
  x86/x2apic: Clarify remapping mode for x2apic enablement
  x86/x2apic: Move code in conditional region
  ...

18 files changed, 436 insertions, 501 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 85588a891c06..5e28e2be3a41 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -856,6 +856,10 @@ config SCHED_MC
 
 source "kernel/Kconfig.preempt"
 
+config UP_LATE_INIT
+       def_bool y
+       depends on !SMP && X86_LOCAL_APIC
+
 config X86_UP_APIC
 	bool "Local APIC support on uniprocessors"
 	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 465b309af254..92003f3c8a42 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -106,7 +106,14 @@ extern u32 native_safe_apic_wait_icr_idle(void);
 extern void native_apic_icr_write(u32 low, u32 id);
 extern u64 native_apic_icr_read(void);
 
-extern int x2apic_mode;
+static inline bool apic_is_x2apic_enabled(void)
+{
+	u64 msr;
+
+	if (rdmsrl_safe(MSR_IA32_APICBASE, &msr))
+		return false;
+	return msr & X2APIC_ENABLE;
+}
 
 #ifdef CONFIG_X86_X2APIC
 /*
@@ -169,48 +176,23 @@ static inline u64 native_x2apic_icr_read(void)
 	return val;
 }
 
+extern int x2apic_mode;
 extern int x2apic_phys;
-extern int x2apic_preenabled;
-extern void check_x2apic(void);
-extern void enable_x2apic(void);
+extern void __init check_x2apic(void);
+extern void x2apic_setup(void);
 static inline int x2apic_enabled(void)
 {
-	u64 msr;
-
-	if (!cpu_has_x2apic)
-		return 0;
-
-	rdmsrl(MSR_IA32_APICBASE, msr);
-	if (msr & X2APIC_ENABLE)
-		return 1;
-	return 0;
+	return cpu_has_x2apic && apic_is_x2apic_enabled();
 }
 
 #define x2apic_supported()	(cpu_has_x2apic)
-static inline void x2apic_force_phys(void)
-{
-	x2apic_phys = 1;
-}
 #else
-static inline void disable_x2apic(void)
-{
-}
-static inline void check_x2apic(void)
-{
-}
-static inline void enable_x2apic(void)
-{
-}
-static inline int x2apic_enabled(void)
-{
-	return 0;
-}
-static inline void x2apic_force_phys(void)
-{
-}
+static inline void check_x2apic(void) { }
+static inline void x2apic_setup(void) { }
+static inline int x2apic_enabled(void) { return 0; }
 
-#define	x2apic_preenabled 0
-#define	x2apic_supported()	0
+#define x2apic_mode		(0)
+#define	x2apic_supported()	(0)
 #endif
 
 extern void enable_IR_x2apic(void);
@@ -219,7 +201,6 @@ extern int get_physical_broadcast(void);
 
 extern int lapic_get_maxlvt(void);
 extern void clear_local_APIC(void);
-extern void connect_bsp_APIC(void);
 extern void disconnect_bsp_APIC(int virt_wire_setup);
 extern void disable_local_APIC(void);
 extern void lapic_shutdown(void);
@@ -227,8 +208,6 @@ extern int verify_local_APIC(void);
 extern void sync_Arb_IDs(void);
 extern void init_bsp_APIC(void);
 extern void setup_local_APIC(void);
-extern void end_local_APIC_setup(void);
-extern void bsp_end_local_APIC_setup(void);
 extern void init_apic_mappings(void);
 void register_lapic_address(unsigned long address);
 extern void setup_boot_APIC_clock(void);
@@ -236,6 +215,9 @@ extern void setup_secondary_APIC_clock(void);
 extern int APIC_init_uniprocessor(void);
 extern int apic_force_enable(unsigned long addr);
 
+extern int apic_bsp_setup(bool upmode);
+extern void apic_ap_setup(void);
+
 /*
  * On 32bit this is mach-xxx local
  */
diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index bf006cce9418..2f91685fe1cd 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -279,6 +279,11 @@ static inline void disable_ioapic_support(void) { }
 #define native_ioapic_set_affinity	NULL
 #define native_setup_ioapic_entry	NULL
 #define native_eoi_ioapic_pin		NULL
+
+static inline void setup_IO_APIC(void) { }
+static inline void enable_IO_APIC(void) { }
+static inline void setup_ioapic_dest(void) { }
+
 #endif
 
 #endif /* _ASM_X86_IO_APIC_H */
diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
index b7747c4c2cf2..6224d316c405 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -33,8 +33,6 @@ struct irq_cfg;
 
 #ifdef CONFIG_IRQ_REMAP
 
-extern void setup_irq_remapping_ops(void);
-extern int irq_remapping_supported(void);
 extern void set_irq_remapping_broken(void);
 extern int irq_remapping_prepare(void);
 extern int irq_remapping_enable(void);
@@ -60,8 +58,6 @@ void irq_remap_modify_chip_defaults(struct irq_chip *chip);
 
 #else  /* CONFIG_IRQ_REMAP */
 
-static inline void setup_irq_remapping_ops(void) { }
-static inline int irq_remapping_supported(void) { return 0; }
 static inline void set_irq_remapping_broken(void) { }
 static inline int irq_remapping_prepare(void) { return -ENODEV; }
 static inline int irq_remapping_enable(void) { return -ENODEV; }
diff --git a/arch/x86/include/asm/smpboot_hooks.h b/arch/x86/include/asm/smpboot_hooks.h
deleted file mode 100644
index 0da7409f0bec..000000000000
--- a/arch/x86/include/asm/smpboot_hooks.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/* two abstractions specific to kernel/smpboot.c, mainly to cater to visws
- * which needs to alter them. */
-
-static inline void smpboot_clear_io_apic_irqs(void)
-{
-#ifdef CONFIG_X86_IO_APIC
-	io_apic_irqs = 0;
-#endif
-}
-
-static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&rtc_lock, flags);
-	CMOS_WRITE(0xa, 0xf);
-	spin_unlock_irqrestore(&rtc_lock, flags);
-	local_flush_tlb();
-	pr_debug("1.\n");
-	*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) =
-							start_eip >> 4;
-	pr_debug("2.\n");
-	*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) =
-							start_eip & 0xf;
-	pr_debug("3.\n");
-}
-
-static inline void smpboot_restore_warm_reset_vector(void)
-{
-	unsigned long flags;
-
-	/*
-	 * Install writable page 0 entry to set BIOS data area.
-	 */
-	local_flush_tlb();
-
-	/*
-	 * Paranoid:  Set warm reset code and vector here back
-	 * to default values.
-	 */
-	spin_lock_irqsave(&rtc_lock, flags);
-	CMOS_WRITE(0, 0xf);
-	spin_unlock_irqrestore(&rtc_lock, flags);
-
-	*((volatile u32 *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = 0;
-}
-
-static inline void __init smpboot_setup_io_apic(void)
-{
-#ifdef CONFIG_X86_IO_APIC
-	/*
-	 * Here we can be sure that there is an IO-APIC in the system. Let's
-	 * go and set it up:
-	 */
-	if (!skip_ioapic_setup && nr_ioapics)
-		setup_IO_APIC();
-	else {
-		nr_ioapics = 0;
-	}
-#endif
-}
-
-static inline void smpboot_clear_io_apic(void)
-{
-#ifdef CONFIG_X86_IO_APIC
-	nr_ioapics = 0;
-#endif
-}
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index b9e30daa0881..a18fff361c7f 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -653,6 +653,7 @@ static int acpi_register_gsi_pic(struct device *dev, u32 gsi,
 	return gsi;
 }
 
+#ifdef CONFIG_X86_LOCAL_APIC
 static int acpi_register_gsi_ioapic(struct device *dev, u32 gsi,
 				    int trigger, int polarity)
 {
@@ -675,6 +676,7 @@ static void acpi_unregister_gsi_ioapic(u32 gsi)
 	mutex_unlock(&acpi_ioapic_lock);
 #endif
 }
+#endif
 
 int (*__acpi_register_gsi)(struct device *dev, u32 gsi,
 			   int trigger, int polarity) = acpi_register_gsi_pic;
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 29b5b18afa27..b665d241efad 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -134,9 +134,6 @@ static inline void imcr_apic_to_pic(void)
  */
 static int force_enable_local_apic __initdata;
 
-/* Control whether x2APIC mode is enabled or not */
-static bool nox2apic __initdata;
-
 /*
  * APIC command line parameters
  */
@@ -161,33 +158,6 @@ static __init int setup_apicpmtimer(char *s)
 __setup("apicpmtimer", setup_apicpmtimer);
 #endif
 
-int x2apic_mode;
-#ifdef CONFIG_X86_X2APIC
-/* x2apic enabled before OS handover */
-int x2apic_preenabled;
-static int x2apic_disabled;
-static int __init setup_nox2apic(char *str)
-{
-	if (x2apic_enabled()) {
-		int apicid = native_apic_msr_read(APIC_ID);
-
-		if (apicid >= 255) {
-			pr_warning("Apicid: %08x, cannot enforce nox2apic\n",
-				   apicid);
-			return 0;
-		}
-
-		pr_warning("x2apic already enabled. will disable it\n");
-	} else
-		setup_clear_cpu_cap(X86_FEATURE_X2APIC);
-
-	nox2apic = true;
-
-	return 0;
-}
-early_param("nox2apic", setup_nox2apic);
-#endif
-
 unsigned long mp_lapic_addr;
 int disable_apic;
 /* Disable local APIC timer from the kernel commandline or via dmi quirk */
@@ -1475,7 +1445,7 @@ void setup_local_APIC(void)
 #endif
 }
 
-void end_local_APIC_setup(void)
+static void end_local_APIC_setup(void)
 {
 	lapic_setup_esr();
 
@@ -1492,116 +1462,184 @@ void end_local_APIC_setup(void)
 	apic_pm_activate();
 }
 
-void __init bsp_end_local_APIC_setup(void)
+/*
+ * APIC setup function for application processors. Called from smpboot.c
+ */
+void apic_ap_setup(void)
 {
+	setup_local_APIC();
 	end_local_APIC_setup();
-
-	/*
-	 * Now that local APIC setup is completed for BP, configure the fault
-	 * handling for interrupt remapping.
-	 */
-	irq_remap_enable_fault_handling();
-
 }
 
 #ifdef CONFIG_X86_X2APIC
-/*
- * Need to disable xapic and x2apic at the same time and then enable xapic mode
- */
-static inline void __disable_x2apic(u64 msr)
-{
-	wrmsrl(MSR_IA32_APICBASE,
-	       msr & ~(X2APIC_ENABLE | XAPIC_ENABLE));
-	wrmsrl(MSR_IA32_APICBASE, msr & ~X2APIC_ENABLE);
-}
+int x2apic_mode;
 
-static __init void disable_x2apic(void)
+enum {
+	X2APIC_OFF,
+	X2APIC_ON,
+	X2APIC_DISABLED,
+};
+static int x2apic_state;
+
+static inline void __x2apic_disable(void)
 {
 	u64 msr;
 
-	if (!cpu_has_x2apic)
+	if (cpu_has_apic)
 		return;
 
 	rdmsrl(MSR_IA32_APICBASE, msr);
-	if (msr & X2APIC_ENABLE) {
-		u32 x2apic_id = read_apic_id();
-
-		if (x2apic_id >= 255)
-			panic("Cannot disable x2apic, id: %08x\n", x2apic_id);
+	if (!(msr & X2APIC_ENABLE))
+		return;
+	/* Disable xapic and x2apic first and then reenable xapic mode */
+	wrmsrl(MSR_IA32_APICBASE, msr & ~(X2APIC_ENABLE | XAPIC_ENABLE));
+	wrmsrl(MSR_IA32_APICBASE, msr & ~X2APIC_ENABLE);
+	printk_once(KERN_INFO "x2apic disabled\n");
+}
 
-		pr_info("Disabling x2apic\n");
-		__disable_x2apic(msr);
+static inline void __x2apic_enable(void)
+{
+	u64 msr;
 
-		if (nox2apic) {
-			clear_cpu_cap(&cpu_data(0), X86_FEATURE_X2APIC);
-			setup_clear_cpu_cap(X86_FEATURE_X2APIC);
-		}
+	rdmsrl(MSR_IA32_APICBASE, msr);
+	if (msr & X2APIC_ENABLE)
+		return;
+	wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
+	printk_once(KERN_INFO "x2apic enabled\n");
+}
 
-		x2apic_disabled = 1;
-		x2apic_mode = 0;
+static int __init setup_nox2apic(char *str)
+{
+	if (x2apic_enabled()) {
+		int apicid = native_apic_msr_read(APIC_ID);
 
-		register_lapic_address(mp_lapic_addr);
+		if (apicid >= 255) {
+			pr_warning("Apicid: %08x, cannot enforce nox2apic\n",
+				   apicid);
+			return 0;
+		}
+		pr_warning("x2apic already enabled.\n");
+		__x2apic_disable();
 	}
+	setup_clear_cpu_cap(X86_FEATURE_X2APIC);
+	x2apic_state = X2APIC_DISABLED;
+	x2apic_mode = 0;
+	return 0;
 }
+early_param("nox2apic", setup_nox2apic);
 
-void check_x2apic(void)
+/* Called from cpu_init() to enable x2apic on (secondary) cpus */
+void x2apic_setup(void)
 {
-	if (x2apic_enabled()) {
-		pr_info("x2apic enabled by BIOS, switching to x2apic ops\n");
-		x2apic_preenabled = x2apic_mode = 1;
+	/*
+	 * If x2apic is not in ON state, disable it if already enabled
+	 * from BIOS.
+	 */
+	if (x2apic_state != X2APIC_ON) {
+		__x2apic_disable();
+		return;
 	}
+	__x2apic_enable();
 }
 
-void enable_x2apic(void)
+static __init void x2apic_disable(void)
 {
-	u64 msr;
+	u32 x2apic_id;
 
-	rdmsrl(MSR_IA32_APICBASE, msr);
-	if (x2apic_disabled) {
-		__disable_x2apic(msr);
+	if (x2apic_state != X2APIC_ON)
+		goto out;
+
+	x2apic_id = read_apic_id();
+	if (x2apic_id >= 255)
+		panic("Cannot disable x2apic, id: %08x\n", x2apic_id);
+
+	__x2apic_disable();
+	register_lapic_address(mp_lapic_addr);
+out:
+	x2apic_state = X2APIC_DISABLED;
+	x2apic_mode = 0;
+}
+
+static __init void x2apic_enable(void)
+{
+	if (x2apic_state != X2APIC_OFF)
 		return;
-	}
 
-	if (!x2apic_mode)
+	x2apic_mode = 1;
+	x2apic_state = X2APIC_ON;
+	__x2apic_enable();
+}
+
+static __init void try_to_enable_x2apic(int remap_mode)
+{
+	if (x2apic_state == X2APIC_DISABLED)
 		return;
 
-	if (!(msr & X2APIC_ENABLE)) {
-		printk_once(KERN_INFO "Enabling x2apic\n");
-		wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
+	if (remap_mode != IRQ_REMAP_X2APIC_MODE) {
+		/* IR is required if there is APIC ID > 255 even when running
+		 * under KVM
+		 */
+		if (max_physical_apicid > 255 ||
+		    (IS_ENABLED(CONFIG_HYPERVISOR_GUEST) &&
+		     !hypervisor_x2apic_available())) {
+			pr_info("x2apic: IRQ remapping doesn't support X2APIC mode\n");
+			x2apic_disable();
+			return;
+		}
+
+		/*
+		 * without IR all CPUs can be addressed by IOAPIC/MSI
+		 * only in physical mode
+		 */
+		x2apic_phys = 1;
 	}
+	x2apic_enable();
 }
-#endif /* CONFIG_X86_X2APIC */
 
-int __init enable_IR(void)
+void __init check_x2apic(void)
 {
-#ifdef CONFIG_IRQ_REMAP
-	if (!irq_remapping_supported()) {
-		pr_debug("intr-remapping not supported\n");
-		return -1;
+	if (x2apic_enabled()) {
+		pr_info("x2apic: enabled by BIOS, switching to x2apic ops\n");
+		x2apic_mode = 1;
+		x2apic_state = X2APIC_ON;
+	} else if (!cpu_has_x2apic) {
+		x2apic_state = X2APIC_DISABLED;
 	}
+}
+#else /* CONFIG_X86_X2APIC */
+static int __init validate_x2apic(void)
+{
+	if (!apic_is_x2apic_enabled())
+		return 0;
+	/*
+	 * Checkme: Can we simply turn off x2apic here instead of panic?
+	 */
+	panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n");
+}
+early_initcall(validate_x2apic);
 
-	if (!x2apic_preenabled && skip_ioapic_setup) {
-		pr_info("Skipped enabling intr-remap because of skipping "
-			"io-apic setup\n");
+static inline void try_to_enable_x2apic(int remap_mode) { }
+static inline void __x2apic_enable(void) { }
+#endif /* !CONFIG_X86_X2APIC */
+
+static int __init try_to_enable_IR(void)
+{
+#ifdef CONFIG_X86_IO_APIC
+	if (!x2apic_enabled() && skip_ioapic_setup) {
+		pr_info("Not enabling interrupt remapping due to skipped IO-APIC setup\n");
 		return -1;
 	}
-
-	return irq_remapping_enable();
 #endif
-	return -1;
+	return irq_remapping_enable();
 }
 
 void __init enable_IR_x2apic(void)
 {
 	unsigned long flags;
-	int ret, x2apic_enabled = 0;
-	int hardware_init_ret;
-
-	/* Make sure irq_remap_ops are initialized */
-	setup_irq_remapping_ops();
+	int ret, ir_stat;
 
-	hardware_init_ret = irq_remapping_prepare();
-	if (hardware_init_ret && !x2apic_supported())
+	ir_stat = irq_remapping_prepare();
+	if (ir_stat < 0 && !x2apic_supported())
 		return;
 
 	ret = save_ioapic_entries();
@@ -1614,49 +1652,13 @@ void __init enable_IR_x2apic(void)
 	legacy_pic->mask_all();
 	mask_ioapic_entries();
 
-	if (x2apic_preenabled && nox2apic)
-		disable_x2apic();
-
-	if (hardware_init_ret)
-		ret = -1;
-	else
-		ret = enable_IR();
-
-	if (!x2apic_supported())
-		goto skip_x2apic;
+	/* If irq_remapping_prepare() succeded, try to enable it */
+	if (ir_stat >= 0)
+		ir_stat = try_to_enable_IR();
+	/* ir_stat contains the remap mode or an error code */
+	try_to_enable_x2apic(ir_stat);
 
-	if (ret < 0) {
-		/* IR is required if there is APIC ID > 255 even when running
-		 * under KVM
-		 */
-		if (max_physical_apicid > 255 ||
-		    !hypervisor_x2apic_available()) {
-			if (x2apic_preenabled)
-				disable_x2apic();
-			goto skip_x2apic;
-		}
-		/*
-		 * without IR all CPUs can be addressed by IOAPIC/MSI
-		 * only in physical mode
-		 */
-		x2apic_force_phys();
-	}
-
-	if (ret == IRQ_REMAP_XAPIC_MODE) {
-		pr_info("x2apic not enabled, IRQ remapping is in xapic mode\n");
-		goto skip_x2apic;
-	}
-
-	x2apic_enabled = 1;
-
-	if (x2apic_supported() && !x2apic_mode) {
-		x2apic_mode = 1;
-		enable_x2apic();
-		pr_info("Enabled x2apic\n");
-	}
-
-skip_x2apic:
-	if (ret < 0) /* IR enabling failed */
+	if (ir_stat < 0)
 		restore_ioapic_entries();
 	legacy_pic->restore_mask();
 	local_irq_restore(flags);
@@ -1847,82 +1849,8 @@ void __init register_lapic_address(unsigned long address)
 	}
 }
 
-/*
- * This initializes the IO-APIC and APIC hardware if this is
- * a UP kernel.
- */
 int apic_version[MAX_LOCAL_APIC];
 
-int __init APIC_init_uniprocessor(void)
-{
-	if (disable_apic) {
-		pr_info("Apic disabled\n");
-		return -1;
-	}
-#ifdef CONFIG_X86_64
-	if (!cpu_has_apic) {
-		disable_apic = 1;
-		pr_info("Apic disabled by BIOS\n");
-		return -1;
-	}
-#else
-	if (!smp_found_config && !cpu_has_apic)
-		return -1;
-
-	/*
-	 * Complain if the BIOS pretends there is one.
-	 */
-	if (!cpu_has_apic &&
-	    APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
-		pr_err("BIOS bug, local APIC 0x%x not detected!...\n",
-			boot_cpu_physical_apicid);
-		return -1;
-	}
-#endif
-
-	default_setup_apic_routing();
-
-	verify_local_APIC();
-	connect_bsp_APIC();
-
-#ifdef CONFIG_X86_64
-	apic_write(APIC_ID, SET_APIC_ID(boot_cpu_physical_apicid));
-#else
-	/*
-	 * Hack: In case of kdump, after a crash, kernel might be booting
-	 * on a cpu with non-zero lapic id. But boot_cpu_physical_apicid
-	 * might be zero if read from MP tables. Get it from LAPIC.
-	 */
-# ifdef CONFIG_CRASH_DUMP
-	boot_cpu_physical_apicid = read_apic_id();
-# endif
-#endif
-	physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
-	setup_local_APIC();
-
-#ifdef CONFIG_X86_IO_APIC
-	/*
-	 * Now enable IO-APICs, actually call clear_IO_APIC
-	 * We need clear_IO_APIC before enabling error vector
-	 */
-	if (!skip_ioapic_setup && nr_ioapics)
-		enable_IO_APIC();
-#endif
-
-	bsp_end_local_APIC_setup();
-
-#ifdef CONFIG_X86_IO_APIC
-	if (smp_found_config && !skip_ioapic_setup && nr_ioapics)
-		setup_IO_APIC();
-	else {
-		nr_ioapics = 0;
-	}
-#endif
-
-	x86_init.timers.setup_percpu_clockev();
-	return 0;
-}
-
 /*
  * Local APIC interrupts
  */
@@ -2027,7 +1955,7 @@ __visible void smp_trace_error_interrupt(struct pt_regs *regs)
 /**
  * connect_bsp_APIC - attach the APIC to the interrupt system
  */
-void __init connect_bsp_APIC(void)
+static void __init connect_bsp_APIC(void)
 {
 #ifdef CONFIG_X86_32
 	if (pic_mode) {
@@ -2274,6 +2202,100 @@ void __init apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v))
 	}
 }
 
+static void __init apic_bsp_up_setup(void)
+{
+#ifdef CONFIG_X86_64
+	apic_write(APIC_ID, SET_APIC_ID(boot_cpu_physical_apicid));
+#else
+	/*
+	 * Hack: In case of kdump, after a crash, kernel might be booting
+	 * on a cpu with non-zero lapic id. But boot_cpu_physical_apicid
+	 * might be zero if read from MP tables. Get it from LAPIC.
+	 */
+# ifdef CONFIG_CRASH_DUMP
+	boot_cpu_physical_apicid = read_apic_id();
+# endif
+#endif
+	physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
+}
+
+/**
+ * apic_bsp_setup - Setup function for local apic and io-apic
+ * @upmode:		Force UP mode (for APIC_init_uniprocessor)
+ *
+ * Returns:
+ * apic_id of BSP APIC
+ */
+int __init apic_bsp_setup(bool upmode)
+{
+	int id;
+
+	connect_bsp_APIC();
+	if (upmode)
+		apic_bsp_up_setup();
+	setup_local_APIC();
+
+	if (x2apic_mode)
+		id = apic_read(APIC_LDR);
+	else
+		id = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
+
+	enable_IO_APIC();
+	end_local_APIC_setup();
+	irq_remap_enable_fault_handling();
+	setup_IO_APIC();
+	/* Setup local timer */
+	x86_init.timers.setup_percpu_clockev();
+	return id;
+}
+
+/*
+ * This initializes the IO-APIC and APIC hardware if this is
+ * a UP kernel.
+ */
+int __init APIC_init_uniprocessor(void)
+{
+	if (disable_apic) {
+		pr_info("Apic disabled\n");
+		return -1;
+	}
+#ifdef CONFIG_X86_64
+	if (!cpu_has_apic) {
+		disable_apic = 1;
+		pr_info("Apic disabled by BIOS\n");
+		return -1;
+	}
+#else
+	if (!smp_found_config && !cpu_has_apic)
+		return -1;
+
+	/*
+	 * Complain if the BIOS pretends there is one.
+	 */
+	if (!cpu_has_apic &&
+	    APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
+		pr_err("BIOS bug, local APIC 0x%x not detected!...\n",
+			boot_cpu_physical_apicid);
+		return -1;
+	}
+#endif
+
+	if (!smp_found_config)
+		disable_ioapic_support();
+
+	default_setup_apic_routing();
+	verify_local_APIC();
+	apic_bsp_setup(true);
+	return 0;
+}
+
+#ifdef CONFIG_UP_LATE_INIT
+void __init up_late_init(void)
+{
+	APIC_init_uniprocessor();
+}
+#endif
+
 /*
  * Power management
  */
@@ -2359,9 +2381,9 @@ static void lapic_resume(void)
 	mask_ioapic_entries();
 	legacy_pic->mask_all();
 
-	if (x2apic_mode)
-		enable_x2apic();
-	else {
+	if (x2apic_mode) {
+		__x2apic_enable();
+	} else {
 		/*
 		 * Make sure the APICBASE points to the right address
 		 *
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 3f5f60406ab1..f4dc2462a1ac 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1507,7 +1507,10 @@ void __init enable_IO_APIC(void)
 	int i8259_apic, i8259_pin;
 	int apic, pin;
 
-	if (!nr_legacy_irqs())
+	if (skip_ioapic_setup)
+		nr_ioapics = 0;
+
+	if (!nr_legacy_irqs() || !nr_ioapics)
 		return;
 
 	for_each_ioapic_pin(apic, pin) {
@@ -2295,7 +2298,7 @@ static inline void __init check_timer(void)
 	}
 	local_irq_disable();
 	apic_printk(APIC_QUIET, KERN_INFO "..... failed :(.\n");
-	if (x2apic_preenabled)
+	if (apic_is_x2apic_enabled())
 		apic_printk(APIC_QUIET, KERN_INFO
 			    "Perhaps problem with the pre-enabled x2apic mode\n"
 			    "Try booting with x2apic and interrupt-remapping disabled in the bios.\n");
@@ -2373,9 +2376,9 @@ void __init setup_IO_APIC(void)
 {
 	int ioapic;
 
-	/*
-	 * calling enable_IO_APIC() is moved to setup_local_APIC for BP
-	 */
+	if (skip_ioapic_setup || !nr_ioapics)
+		return;
+
 	io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;
 
 	apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c6049650c093..cb5692551b98 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1332,7 +1332,7 @@ void cpu_init(void)
 	barrier();
 
 	x86_configure_nx();
-	enable_x2apic();
+	x2apic_setup();
 
 	/*
 	 * set up and load the per-CPU TSS
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 6d7022c683e3..febc6aabc72e 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -73,7 +73,6 @@
 #include <asm/setup.h>
 #include <asm/uv/uv.h>
 #include <linux/mc146818rtc.h>
-#include <asm/smpboot_hooks.h>
 #include <asm/i8259.h>
 #include <asm/realmode.h>
 #include <asm/misc.h>
@@ -104,6 +103,43 @@ EXPORT_PER_CPU_SYMBOL(cpu_info);
 
 atomic_t init_deasserted;
 
+static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtc_lock, flags);
+	CMOS_WRITE(0xa, 0xf);
+	spin_unlock_irqrestore(&rtc_lock, flags);
+	local_flush_tlb();
+	pr_debug("1.\n");
+	*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) =
+							start_eip >> 4;
+	pr_debug("2.\n");
+	*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) =
+							start_eip & 0xf;
+	pr_debug("3.\n");
+}
+
+static inline void smpboot_restore_warm_reset_vector(void)
+{
+	unsigned long flags;
+
+	/*
+	 * Install writable page 0 entry to set BIOS data area.
+	 */
+	local_flush_tlb();
+
+	/*
+	 * Paranoid:  Set warm reset code and vector here back
+	 * to default values.
+	 */
+	spin_lock_irqsave(&rtc_lock, flags);
+	CMOS_WRITE(0, 0xf);
+	spin_unlock_irqrestore(&rtc_lock, flags);
+
+	*((volatile u32 *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = 0;
+}
+
 /*
  * Report back to the Boot Processor during boot time or to the caller processor
  * during CPU online.
@@ -136,8 +172,7 @@ static void smp_callin(void)
 	 * CPU, first the APIC. (this is probably redundant on most
 	 * boards)
 	 */
-	setup_local_APIC();
-	end_local_APIC_setup();
+	apic_ap_setup();
 
 	/*
 	 * Need to setup vector mappings before we enable interrupts.
@@ -955,9 +990,12 @@ void arch_disable_smp_support(void)
  */
 static __init void disable_smp(void)
 {
+	pr_info("SMP disabled\n");
+
+	disable_ioapic_support();
+
 	init_cpu_present(cpumask_of(0));
 	init_cpu_possible(cpumask_of(0));
-	smpboot_clear_io_apic_irqs();
 
 	if (smp_found_config)
 		physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
@@ -967,6 +1005,13 @@ static __init void disable_smp(void)
 	cpumask_set_cpu(0, cpu_core_mask(0));
 }
 
+enum {
+	SMP_OK,
+	SMP_NO_CONFIG,
+	SMP_NO_APIC,
+	SMP_FORCE_UP,
+};
+
 /*
  * Various sanity checks.
  */
@@ -1014,10 +1059,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
 	if (!smp_found_config && !acpi_lapic) {
 		preempt_enable();
 		pr_notice("SMP motherboard not detected\n");
-		disable_smp();
-		if (APIC_init_uniprocessor())
-			pr_notice("Local APIC not detected. Using dummy APIC emulation.\n");
-		return -1;
+		return SMP_NO_CONFIG;
 	}
 
 	/*
@@ -1041,9 +1083,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
 				boot_cpu_physical_apicid);
 			pr_err("... forcing use of dummy APIC emulation (tell your hw vendor)\n");
 		}
-		smpboot_clear_io_apic();
-		disable_ioapic_support();
-		return -1;
+		return SMP_NO_APIC;
 	}
 
 	verify_local_APIC();
@@ -1053,15 +1093,10 @@ static int __init smp_sanity_check(unsigned max_cpus)
 	 */
 	if (!max_cpus) {
 		pr_info("SMP mode deactivated\n");
-		smpboot_clear_io_apic();
-
-		connect_bsp_APIC();
-		setup_local_APIC();
-		bsp_end_local_APIC_setup();
-		return -1;
+		return SMP_FORCE_UP;
 	}
 
-	return 0;
+	return SMP_OK;
 }
 
 static void __init smp_cpu_index_default(void)
@@ -1101,10 +1136,21 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 	}
 	set_cpu_sibling_map(0);
 
-	if (smp_sanity_check(max_cpus) < 0) {
-		pr_info("SMP disabled\n");
+	switch (smp_sanity_check(max_cpus)) {
+	case SMP_NO_CONFIG:
 		disable_smp();
+		if (APIC_init_uniprocessor())
+			pr_notice("Local APIC not detected. Using dummy APIC emulation.\n");
 		return;
+	case SMP_NO_APIC:
+		disable_smp();
+		return;
+	case SMP_FORCE_UP:
+		disable_smp();
+		apic_bsp_setup(false);
+		return;
+	case SMP_OK:
+		break;
 	}
 
 	default_setup_apic_routing();
@@ -1115,33 +1161,10 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 		/* Or can we switch back to PIC here? */
 	}
 
-	connect_bsp_APIC();
-
-	/*
-	 * Switch from PIC to APIC mode.
-	 */
-	setup_local_APIC();
-
-	if (x2apic_mode)
-		cpu0_logical_apicid = apic_read(APIC_LDR);
-	else
-		cpu0_logical_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
-
-	/*
-	 * Enable IO APIC before setting up error vector
-	 */
-	if (!skip_ioapic_setup && nr_ioapics)
-		enable_IO_APIC();
-
-	bsp_end_local_APIC_setup();
-	smpboot_setup_io_apic();
-	/*
-	 * Set up local APIC timer on boot CPU.
-	 */
+	cpu0_logical_apicid = apic_bsp_setup(false);
 
 	pr_info("CPU%d: ", 0);
 	print_cpu_info(&cpu_data(0));
-	x86_init.timers.setup_percpu_clockev();
 
 	if (is_uv_system())
 		uv_system_init();
@@ -1177,9 +1200,7 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
 
 	nmi_selftest();
 	impress_friends();
-#ifdef CONFIG_X86_IO_APIC
 	setup_ioapic_dest();
-#endif
 	mtrr_aps_init();
 }
 
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 98024856df07..59de6364a910 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -4284,7 +4284,6 @@ static int alloc_hpet_msi(unsigned int irq, unsigned int id)
 }
 
 struct irq_remap_ops amd_iommu_irq_ops = {
-	.supported		= amd_iommu_supported,
 	.prepare		= amd_iommu_prepare,
 	.enable			= amd_iommu_enable,
 	.disable		= amd_iommu_disable,
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index b0522f15730f..9a20248e7068 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2014,9 +2014,6 @@ static bool detect_ivrs(void)
 	/* Make sure ACS will be enabled during PCI probe */
 	pci_request_acs();
 
-	if (!disable_irq_remap)
-		amd_iommu_irq_remap = true;
-
 	return true;
 }
 
@@ -2123,12 +2120,14 @@ static int __init iommu_go_to_state(enum iommu_init_state state)
 #ifdef CONFIG_IRQ_REMAP
 int __init amd_iommu_prepare(void)
 {
-	return iommu_go_to_state(IOMMU_ACPI_FINISHED);
-}
+	int ret;
 
-int __init amd_iommu_supported(void)
-{
-	return amd_iommu_irq_remap ? 1 : 0;
+	amd_iommu_irq_remap = true;
+
+	ret = iommu_go_to_state(IOMMU_ACPI_FINISHED);
+	if (ret)
+		return ret;
+	return amd_iommu_irq_remap ? 0 : -ENODEV;
 }
 
 int __init amd_iommu_enable(void)
diff --git a/drivers/iommu/amd_iommu_proto.h b/drivers/iommu/amd_iommu_proto.h
index 95ed6deae47f..861af9d8338a 100644
--- a/drivers/iommu/amd_iommu_proto.h
+++ b/drivers/iommu/amd_iommu_proto.h
@@ -33,7 +33,6 @@ extern void amd_iommu_init_notifier(void);
 extern void amd_iommu_init_api(void);
 
 /* Needed for interrupt remapping */
-extern int amd_iommu_supported(void);
 extern int amd_iommu_prepare(void);
 extern int amd_iommu_enable(void);
 extern void amd_iommu_disable(void);
diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index a55b207b9425..14de1ab223c8 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -32,8 +32,9 @@ struct hpet_scope {
 };
 
 #define IR_X2APIC_MODE(mode) (mode ? (1 << 11) : 0)
-#define IRTE_DEST(dest) ((x2apic_mode) ? dest : dest << 8)
+#define IRTE_DEST(dest) ((eim_mode) ? dest : dest << 8)
 
+static int __read_mostly eim_mode;
 static struct ioapic_scope ir_ioapic[MAX_IO_APICS];
 static struct hpet_scope ir_hpet[MAX_HPET_TBS];
 
@@ -481,11 +482,11 @@ static int intel_setup_irq_remapping(struct intel_iommu *iommu)
 	if (iommu->ir_table)
 		return 0;
 
-	ir_table = kzalloc(sizeof(struct ir_table), GFP_ATOMIC);
+	ir_table = kzalloc(sizeof(struct ir_table), GFP_KERNEL);
 	if (!ir_table)
 		return -ENOMEM;
 
-	pages = alloc_pages_node(iommu->node, GFP_ATOMIC | __GFP_ZERO,
+	pages = alloc_pages_node(iommu->node, GFP_KERNEL | __GFP_ZERO,
 				 INTR_REMAP_PAGE_ORDER);
 
 	if (!pages) {
@@ -566,13 +567,27 @@ static int __init dmar_x2apic_optout(void)
 	return dmar->flags & DMAR_X2APIC_OPT_OUT;
 }
 
-static int __init intel_irq_remapping_supported(void)
+static void __init intel_cleanup_irq_remapping(void)
+{
+	struct dmar_drhd_unit *drhd;
+	struct intel_iommu *iommu;
+
+	for_each_iommu(iommu, drhd) {
+		if (ecap_ir_support(iommu->ecap)) {
+			iommu_disable_irq_remapping(iommu);
+			intel_teardown_irq_remapping(iommu);
+		}
+	}
+
+	if (x2apic_supported())
+		pr_warn("Failed to enable irq remapping.  You are vulnerable to irq-injection attacks.\n");
+}
+
+static int __init intel_prepare_irq_remapping(void)
 {
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
 
-	if (disable_irq_remap)
-		return 0;
 	if (irq_remap_broken) {
 		printk(KERN_WARNING
 			"This system BIOS has enabled interrupt remapping\n"
@@ -581,38 +596,45 @@ static int __init intel_irq_remapping_supported(void)
 			"interrupt remapping is being disabled.  Please\n"
 			"contact your BIOS vendor for an update\n");
 		add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
-		disable_irq_remap = 1;
-		return 0;
+		return -ENODEV;
 	}
 
+	if (dmar_table_init() < 0)
+		return -ENODEV;
+
 	if (!dmar_ir_support())
-		return 0;
+		return -ENODEV;
+
+	if (parse_ioapics_under_ir() != 1) {
+		printk(KERN_INFO "Not enabling interrupt remapping\n");
+		goto error;
+	}
 
+	/* First make sure all IOMMUs support IRQ remapping */
 	for_each_iommu(iommu, drhd)
 		if (!ecap_ir_support(iommu->ecap))
-			return 0;
+			goto error;
 
-	return 1;
+	/* Do the allocations early */
+	for_each_iommu(iommu, drhd)
+		if (intel_setup_irq_remapping(iommu))
+			goto error;
+
+	return 0;
+
+error:
+	intel_cleanup_irq_remapping();
+	return -ENODEV;
 }
 
 static int __init intel_enable_irq_remapping(void)
 {
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
-	bool x2apic_present;
 	int setup = 0;
 	int eim = 0;
 
-	x2apic_present = x2apic_supported();
-
-	if (parse_ioapics_under_ir() != 1) {
-		printk(KERN_INFO "Not enable interrupt remapping\n");
-		goto error;
-	}
-
-	if (x2apic_present) {
-		pr_info("Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");
-
+	if (x2apic_supported()) {
 		eim = !dmar_x2apic_optout();
 		if (!eim)
 			printk(KERN_WARNING
@@ -646,16 +668,15 @@ static int __init intel_enable_irq_remapping(void)
 	/*
 	 * check for the Interrupt-remapping support
 	 */
-	for_each_iommu(iommu, drhd) {
-		if (!ecap_ir_support(iommu->ecap))
-			continue;
-
+	for_each_iommu(iommu, drhd)
 		if (eim && !ecap_eim_support(iommu->ecap)) {
 			printk(KERN_INFO "DRHD %Lx: EIM not supported by DRHD, "
 			       " ecap %Lx\n", drhd->reg_base_addr, iommu->ecap);
-			goto error;
+			eim = 0;
 		}
-	}
+	eim_mode = eim;
+	if (eim)
+		pr_info("Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");
 
 	/*
 	 * Enable queued invalidation for all the DRHD's.
@@ -675,12 +696,6 @@ static int __init intel_enable_irq_remapping(void)
 	 * Setup Interrupt-remapping for all the DRHD's now.
 	 */
 	for_each_iommu(iommu, drhd) {
-		if (!ecap_ir_support(iommu->ecap))
-			continue;
-
-		if (intel_setup_irq_remapping(iommu))
-			goto error;
-
 		iommu_set_irq_remapping(iommu, eim);
 		setup = 1;
 	}
@@ -702,15 +717,7 @@ static int __init intel_enable_irq_remapping(void)
 	return eim ? IRQ_REMAP_X2APIC_MODE : IRQ_REMAP_XAPIC_MODE;
 
 error:
-	for_each_iommu(iommu, drhd)
-		if (ecap_ir_support(iommu->ecap)) {
-			iommu_disable_irq_remapping(iommu);
-			intel_teardown_irq_remapping(iommu);
-		}
-
-	if (x2apic_present)
-		pr_warn("Failed to enable irq remapping.  You are vulnerable to irq-injection attacks.\n");
-
+	intel_cleanup_irq_remapping();
 	return -1;
 }
 
@@ -1199,8 +1206,7 @@ static int intel_alloc_hpet_msi(unsigned int irq, unsigned int id)
 }
 
 struct irq_remap_ops intel_irq_remap_ops = {
-	.supported		= intel_irq_remapping_supported,
-	.prepare		= dmar_table_init,
+	.prepare		= intel_prepare_irq_remapping,
 	.enable			= intel_enable_irq_remapping,
 	.disable		= disable_irq_remapping,
 	.reenable		= reenable_irq_remapping,
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 89c4846683be..390079ee1350 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -17,12 +17,11 @@
 #include "irq_remapping.h"
 
 int irq_remapping_enabled;
-
-int disable_irq_remap;
 int irq_remap_broken;
 int disable_sourceid_checking;
 int no_x2apic_optout;
 
+static int disable_irq_remap;
 static struct irq_remap_ops *remap_ops;
 
 static int msi_alloc_remapped_irq(struct pci_dev *pdev, int irq, int nvec);
@@ -194,45 +193,32 @@ static __init int setup_irqremap(char *str)
 }
 early_param("intremap", setup_irqremap);
 
-void __init setup_irq_remapping_ops(void)
-{
-	remap_ops = &intel_irq_remap_ops;
-
-#ifdef CONFIG_AMD_IOMMU
-	if (amd_iommu_irq_ops.prepare() == 0)
-		remap_ops = &amd_iommu_irq_ops;
-#endif
-}
-
 void set_irq_remapping_broken(void)
 {
 	irq_remap_broken = 1;
 }
 
-int irq_remapping_supported(void)
+int __init irq_remapping_prepare(void)
 {
 	if (disable_irq_remap)
-		return 0;
-
-	if (!remap_ops || !remap_ops->supported)
-		return 0;
-
-	return remap_ops->supported();
-}
+		return -ENOSYS;
 
-int __init irq_remapping_prepare(void)
-{
-	if (!remap_ops || !remap_ops->prepare)
-		return -ENODEV;
+	if (intel_irq_remap_ops.prepare() == 0)
+		remap_ops = &intel_irq_remap_ops;
+	else if (IS_ENABLED(CONFIG_AMD_IOMMU) &&
+		 amd_iommu_irq_ops.prepare() == 0)
+		remap_ops = &amd_iommu_irq_ops;
+	else
+		return -ENOSYS;
 
-	return remap_ops->prepare();
+	return 0;
 }
 
 int __init irq_remapping_enable(void)
 {
 	int ret;
 
-	if (!remap_ops || !remap_ops->enable)
+	if (!remap_ops->enable)
 		return -ENODEV;
 
 	ret = remap_ops->enable();
@@ -245,22 +231,16 @@ int __init irq_remapping_enable(void)
 
 void irq_remapping_disable(void)
 {
-	if (!irq_remapping_enabled ||
-	    !remap_ops ||
-	    !remap_ops->disable)
-		return;
-
-	remap_ops->disable();
+	if (irq_remapping_enabled && remap_ops->disable)
+		remap_ops->disable();
 }
 
 int irq_remapping_reenable(int mode)
 {
-	if (!irq_remapping_enabled ||
-	    !remap_ops ||
-	    !remap_ops->reenable)
-		return 0;
+	if (irq_remapping_enabled && remap_ops->reenable)
+		return remap_ops->reenable(mode);
 
-	return remap_ops->reenable(mode);
+	return 0;
 }
 
 int __init irq_remap_enable_fault_handling(void)
@@ -268,7 +248,7 @@ int __init irq_remap_enable_fault_handling(void)
 	if (!irq_remapping_enabled)
 		return 0;
 
-	if (!remap_ops || !remap_ops->enable_faulting)
+	if (!remap_ops->enable_faulting)
 		return -ENODEV;
 
 	return remap_ops->enable_faulting();
@@ -279,7 +259,7 @@ int setup_ioapic_remapped_entry(int irq,
 				unsigned int destination, int vector,
 				struct io_apic_irq_attr *attr)
 {
-	if (!remap_ops || !remap_ops->setup_ioapic_entry)
+	if (!remap_ops->setup_ioapic_entry)
 		return -ENODEV;
 
 	return remap_ops->setup_ioapic_entry(irq, entry, destination,
@@ -289,8 +269,7 @@ int setup_ioapic_remapped_entry(int irq,
 static int set_remapped_irq_affinity(struct irq_data *data,
 				     const struct cpumask *mask, bool force)
 {
-	if (!config_enabled(CONFIG_SMP) || !remap_ops ||
-	    !remap_ops->set_affinity)
+	if (!config_enabled(CONFIG_SMP) || !remap_ops->set_affinity)
 		return 0;
 
 	return remap_ops->set_affinity(data, mask, force);
@@ -300,10 +279,7 @@ void free_remapped_irq(int irq)
 {
 	struct irq_cfg *cfg = irq_cfg(irq);
 
-	if (!remap_ops || !remap_ops->free_irq)
-		return;
-
-	if (irq_remapped(cfg))
+	if (irq_remapped(cfg) && remap_ops->free_irq)
 		remap_ops->free_irq(irq);
 }
 
@@ -315,13 +291,13 @@ void compose_remapped_msi_msg(struct pci_dev *pdev,
 
 	if (!irq_remapped(cfg))
 		native_compose_msi_msg(pdev, irq, dest, msg, hpet_id);
-	else if (remap_ops && remap_ops->compose_msi_msg)
+	else if (remap_ops->compose_msi_msg)
 		remap_ops->compose_msi_msg(pdev, irq, dest, msg, hpet_id);
 }
 
 static int msi_alloc_remapped_irq(struct pci_dev *pdev, int irq, int nvec)
 {
-	if (!remap_ops || !remap_ops->msi_alloc_irq)
+	if (!remap_ops->msi_alloc_irq)
 		return -ENODEV;
 
 	return remap_ops->msi_alloc_irq(pdev, irq, nvec);
@@ -330,7 +306,7 @@ static int msi_alloc_remapped_irq(struct pci_dev *pdev, int irq, int nvec)
 static int msi_setup_remapped_irq(struct pci_dev *pdev, unsigned int irq,
 				  int index, int sub_handle)
 {
-	if (!remap_ops || !remap_ops->msi_setup_irq)
+	if (!remap_ops->msi_setup_irq)
 		return -ENODEV;
 
 	return remap_ops->msi_setup_irq(pdev, irq, index, sub_handle);
@@ -340,7 +316,7 @@ int setup_hpet_msi_remapped(unsigned int irq, unsigned int id)
 {
 	int ret;
 
-	if (!remap_ops || !remap_ops->alloc_hpet_msi)
+	if (!remap_ops->alloc_hpet_msi)
 		return -ENODEV;
 
 	ret = remap_ops->alloc_hpet_msi(irq, id);
diff --git a/drivers/iommu/irq_remapping.h b/drivers/iommu/irq_remapping.h
index fde250f86e60..c448eb48340a 100644
--- a/drivers/iommu/irq_remapping.h
+++ b/drivers/iommu/irq_remapping.h
@@ -31,16 +31,12 @@ struct cpumask;
 struct pci_dev;
 struct msi_msg;
 
-extern int disable_irq_remap;
 extern int irq_remap_broken;
 extern int disable_sourceid_checking;
 extern int no_x2apic_optout;
 extern int irq_remapping_enabled;
 
 struct irq_remap_ops {
-	/* Check whether Interrupt Remapping is supported */
-	int (*supported)(void);
-
 	/* Initializes hardware and makes it ready for remapping interrupts */
 	int  (*prepare)(void);
 
@@ -89,7 +85,6 @@ extern struct irq_remap_ops amd_iommu_irq_ops;
 #else  /* CONFIG_IRQ_REMAP */
 
 #define irq_remapping_enabled 0
-#define disable_irq_remap     1
 #define irq_remap_broken      0
 
 #endif /* CONFIG_IRQ_REMAP */
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 93dff5fff524..be91db2a7017 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -151,6 +151,13 @@ smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,
 static inline void kick_all_cpus_sync(void) {  }
 static inline void wake_up_all_idle_cpus(void) {  }
 
+#ifdef CONFIG_UP_LATE_INIT
+extern void __init up_late_init(void);
+static inline void smp_init(void) { up_late_init(); }
+#else
+static inline void smp_init(void) { }
+#endif
+
 #endif /* !SMP */
 
 /*
diff --git a/init/main.c b/init/main.c
index 61b993767db5..179ada15d08a 100644
--- a/init/main.c
+++ b/init/main.c
@@ -87,10 +87,6 @@
 #include <asm/sections.h>
 #include <asm/cacheflush.h>
 
-#ifdef CONFIG_X86_LOCAL_APIC
-#include <asm/smp.h>
-#endif
-
 static int kernel_init(void *);
 
 extern void init_IRQ(void);
@@ -351,15 +347,6 @@ __setup("rdinit=", rdinit_setup);
 
 #ifndef CONFIG_SMP
 static const unsigned int setup_max_cpus = NR_CPUS;
-#ifdef CONFIG_X86_LOCAL_APIC
-static void __init smp_init(void)
-{
-	APIC_init_uniprocessor();
-}
-#else
-#define smp_init()	do { } while (0)
-#endif
-
 static inline void setup_nr_cpu_ids(void) { }
 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 #endif