diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 4915acdbfcd8d9..5bb481aefcbcdc 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -351,10 +351,8 @@ static void kvm_recalculate_logical_map(struct kvm_apic_map *new,
 	 * reversing the LDR calculation to get cluster of APICs, i.e. no
 	 * additional work is required.
 	 */
-	if (apic_x2apic_mode(apic)) {
-		WARN_ON_ONCE(ldr != kvm_apic_calc_x2apic_ldr(kvm_x2apic_id(apic)));
+	if (apic_x2apic_mode(apic))
 		return;
-	}
 
 	if (WARN_ON_ONCE(!kvm_apic_map_get_logical_dest(new, ldr,
 							&cluster, &mask))) {
@@ -2966,18 +2964,28 @@ static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
 		struct kvm_lapic_state *s, bool set)
 {
 	if (apic_x2apic_mode(vcpu->arch.apic)) {
+		u32 x2apic_id = kvm_x2apic_id(vcpu->arch.apic);
 		u32 *id = (u32 *)(s->regs + APIC_ID);
 		u32 *ldr = (u32 *)(s->regs + APIC_LDR);
 		u64 icr;
 
 		if (vcpu->kvm->arch.x2apic_format) {
-			if (*id != vcpu->vcpu_id)
+			if (*id != x2apic_id)
 				return -EINVAL;
 		} else {
+			/*
+			 * Ignore the userspace value when setting APIC state.
+			 * KVM's model is that the x2APIC ID is readonly, e.g.
+			 * KVM only supports delivering interrupts to KVM's
+			 * version of the x2APIC ID.  However, for backwards
+			 * compatibility, don't reject attempts to set a
+			 * mismatched ID for userspace that hasn't opted into
+			 * x2apic_format.
+			 */
 			if (set)
-				*id >>= 24;
+				*id = x2apic_id;
 			else
-				*id <<= 24;
+				*id = x2apic_id << 24;
 		}
 
 		/*
@@ -2986,7 +2994,7 @@ static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
 		 * split to ICR+ICR2 in userspace for backwards compatibility.
 		 */
 		if (set) {
-			*ldr = kvm_apic_calc_x2apic_ldr(*id);
+			*ldr = kvm_apic_calc_x2apic_ldr(x2apic_id);
 
 			icr = __kvm_lapic_get_reg(s->regs, APIC_ICR) |
 			      (u64)__kvm_lapic_get_reg(s->regs, APIC_ICR2) << 32;