diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 47bedb88c9388..108fdc25f90ba 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -247,7 +247,7 @@ static inline int x2apic_enabled(void)
 #else /* !CONFIG_X86_X2APIC */
 static inline void x2apic_setup(void) { }
 static inline int x2apic_enabled(void) { return 0; }
-
+static inline u32 native_apic_msr_read(u32 reg) { BUG(); }
 #define x2apic_mode		(0)
 #define	x2apic_supported()	(0)
 #endif /* !CONFIG_X86_X2APIC */
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index d6b505942c7ff..e26447aa469e9 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1318,8 +1318,7 @@ static int __init __apic_intr_mode_select(void)
 	if (!boot_cpu_has(X86_FEATURE_APIC) &&
 		APIC_INTEGRATED(boot_cpu_apic_version)) {
 		apic_is_disabled = true;
-		pr_err(FW_BUG "Local APIC %d not detected, force emulation\n",
-				       boot_cpu_physical_apicid);
+		pr_err(FW_BUG "Local APIC not detected, force emulation\n");
 		return APIC_PIC;
 	}
 #endif
@@ -1340,12 +1339,6 @@ static int __init __apic_intr_mode_select(void)
 		pr_info("APIC: SMP mode deactivated\n");
 		return APIC_SYMMETRIC_IO_NO_ROUTING;
 	}
-
-	if (read_apic_id() != boot_cpu_physical_apicid) {
-		panic("Boot APIC ID in local APIC unexpected (%d vs %d)",
-		     read_apic_id(), boot_cpu_physical_apicid);
-		/* Or can we switch back to PIC here? */
-	}
 #endif
 
 	return APIC_SYMMETRIC_IO;
@@ -1741,6 +1734,23 @@ void apic_ap_setup(void)
 	end_local_APIC_setup();
 }
 
+static __init void apic_read_boot_cpu_id(bool x2apic)
+{
+	/*
+	 * This can be invoked from check_x2apic() before the APIC has been
+	 * selected. But that code knows for sure that the BIOS enabled
+	 * X2APIC.
+	 */
+	if (x2apic) {
+		boot_cpu_physical_apicid = native_apic_msr_read(APIC_ID);
+		boot_cpu_apic_version = GET_APIC_VERSION(native_apic_msr_read(APIC_LVR));
+	} else {
+		boot_cpu_physical_apicid = read_apic_id();
+		boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
+	}
+}
+
+
 #ifdef CONFIG_X86_X2APIC
 int x2apic_mode;
 EXPORT_SYMBOL_GPL(x2apic_mode);
@@ -1921,6 +1931,7 @@ void __init check_x2apic(void)
 			x2apic_state = X2APIC_ON_LOCKED;
 		else
 			x2apic_state = X2APIC_ON;
+		apic_read_boot_cpu_id(true);
 	} else if (!boot_cpu_has(X86_FEATURE_X2APIC)) {
 		x2apic_state = X2APIC_DISABLED;
 	}
@@ -2109,15 +2120,11 @@ static int __init detect_init_APIC(void)
  */
 void __init init_apic_mappings(void)
 {
-	unsigned int new_apicid;
-
 	if (apic_validate_deadline_timer())
 		pr_info("TSC deadline timer available\n");
 
-	if (x2apic_mode) {
-		boot_cpu_physical_apicid = read_apic_id();
+	if (x2apic_mode)
 		return;
-	}
 
 	/* If no local APIC can be found return early */
 	if (!smp_found_config && detect_init_APIC()) {
@@ -2134,39 +2141,19 @@ void __init init_apic_mappings(void)
 		if (!acpi_lapic && !smp_found_config)
 			register_lapic_address(apic_phys);
 	}
-
-	/*
-	 * Fetch the APIC ID of the BSP in case we have a
-	 * default configuration (or the MP table is broken).
-	 */
-	new_apicid = read_apic_id();
-	if (boot_cpu_physical_apicid != new_apicid) {
-		boot_cpu_physical_apicid = new_apicid;
-		/*
-		 * yeah -- we lie about apic_version
-		 * in case if apic was disabled via boot option
-		 * but it's not a problem for SMP compiled kernel
-		 * since apic_intr_mode_select is prepared for such
-		 * a case and disable smp mode
-		 */
-		boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
-	}
 }
 
 void __init register_lapic_address(unsigned long address)
 {
 	mp_lapic_addr = address;
 
-	if (!x2apic_mode) {
-		set_fixmap_nocache(FIX_APIC_BASE, address);
-		apic_mmio_base = APIC_BASE;
-		apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
-			    APIC_BASE, address);
-	}
-	if (boot_cpu_physical_apicid == -1U) {
-		boot_cpu_physical_apicid  = read_apic_id();
-		boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
-	}
+	if (x2apic_mode)
+		return;
+
+	set_fixmap_nocache(FIX_APIC_BASE, address);
+	apic_mmio_base = APIC_BASE;
+	apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n", APIC_BASE, address);
+	apic_read_boot_cpu_id(false);
 }
 
 /*
@@ -2446,31 +2433,15 @@ int generic_processor_info(int apicid, int version)
 				phys_cpu_present_map);
 
 	/*
-	 * boot_cpu_physical_apicid is designed to have the apicid
-	 * returned by read_apic_id(), i.e, the apicid of the
-	 * currently booting-up processor. However, on some platforms,
-	 * it is temporarily modified by the apicid reported as BSP
-	 * through MP table. Concretely:
-	 *
-	 * - arch/x86/kernel/mpparse.c: MP_processor_info()
-	 * - arch/x86/mm/amdtopology.c: amd_numa_init()
-	 *
-	 * This function is executed with the modified
-	 * boot_cpu_physical_apicid. So, disabled_cpu_apicid kernel
-	 * parameter doesn't work to disable APs on kdump 2nd kernel.
-	 *
-	 * Since fixing handling of boot_cpu_physical_apicid requires
-	 * another discussion and tests on each platform, we leave it
-	 * for now and here we use read_apic_id() directly in this
-	 * function, generic_processor_info().
+	 * boot_cpu_physical_apicid is guaranteed to contain the boot CPU
+	 * APIC ID read from the local APIC when this function is invoked.
 	 */
-	if (disabled_cpu_apicid != BAD_APICID &&
-	    disabled_cpu_apicid != read_apic_id() &&
+	if (disabled_cpu_apicid != boot_cpu_physical_apicid &&
 	    disabled_cpu_apicid == apicid) {
 		int thiscpu = num_processors + disabled_cpus;
 
-		pr_warn("APIC: Disabling requested cpu."
-			" Processor %d/0x%x ignored.\n", thiscpu, apicid);
+		pr_warn("APIC: Disabling requested cpu. Processor %d/0x%x ignored.\n",
+			thiscpu, apicid);
 
 		disabled_cpus++;
 		return -ENODEV;
@@ -2626,15 +2597,6 @@ static void __init apic_bsp_up_setup(void)
 {
 #ifdef CONFIG_X86_64
 	apic_write(APIC_ID, apic->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);
 }
diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
index fed721f90116f..fe9a7f63d2d93 100644
--- a/arch/x86/kernel/mpparse.c
+++ b/arch/x86/kernel/mpparse.c
@@ -58,10 +58,8 @@ static void __init MP_processor_info(struct mpc_cpu *m)
 
 	apicid = m->apicid;
 
-	if (m->cpuflag & CPU_BOOTPROCESSOR) {
+	if (m->cpuflag & CPU_BOOTPROCESSOR)
 		bootup_cpu = " (Bootup-CPU)";
-		boot_cpu_physical_apicid = m->apicid;
-	}
 
 	pr_info("Processor #%d%s\n", m->apicid, bootup_cpu);
 	generic_processor_info(apicid, m->apicver);