diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 51abd44ab8c2dce145d726dc0b3bf7f72da59f78..3b4412c83eec089e13d91db9854f1738f37d6818 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -174,6 +174,7 @@ static inline int apic_is_clustered_box(void)
 extern int setup_APIC_eilvt(u8 lvt_off, u8 vector, u8 msg_type, u8 mask);
 extern void lapic_assign_system_vectors(void);
 extern void lapic_assign_legacy_vector(unsigned int isairq, bool replace);
+extern void lapic_update_legacy_vectors(void);
 extern void lapic_online(void);
 extern void lapic_offline(void);
 extern bool apic_needs_pit(void);
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 539f3e88ca7cdbef2adfbfd567abe2a1501e0f90..24539a05c58c713ac01e9b4b38116abfc742d7f6 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2539,6 +2539,7 @@ static void __init apic_bsp_setup(bool upmode)
 	end_local_APIC_setup();
 	irq_remap_enable_fault_handling();
 	setup_IO_APIC();
+	lapic_update_legacy_vectors();
 }
 
 #ifdef CONFIG_UP_LATE_INIT
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 758bbf25ef748f2d4560eb146af6be2bc65831e1..bd557e9f5dd8eae28c3c77854855cdeebec53116 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -687,6 +687,26 @@ void lapic_assign_legacy_vector(unsigned int irq, bool replace)
 	irq_matrix_assign_system(vector_matrix, ISA_IRQ_VECTOR(irq), replace);
 }
 
+void __init lapic_update_legacy_vectors(void)
+{
+	unsigned int i;
+
+	if (IS_ENABLED(CONFIG_X86_IO_APIC) && nr_ioapics > 0)
+		return;
+
+	/*
+	 * If the IO/APIC is disabled via config, kernel command line or
+	 * lack of enumeration then all legacy interrupts are routed
+	 * through the PIC. Make sure that they are marked as legacy
+	 * vectors. PIC_CASCADE_IRQ has already been marked in
+	 * lapic_assign_system_vectors().
+	 */
+	for (i = 0; i < nr_legacy_irqs(); i++) {
+		if (i != PIC_CASCADE_IR)
+			lapic_assign_legacy_vector(i, true);
+	}
+}
+
 void __init lapic_assign_system_vectors(void)
 {
 	unsigned int i, vector = 0;