KVM: x86: Prevent set vCPU into INIT/SIPI_RECEIVED state when INIT are latched

Commit 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states")
fixed KVM to also latch pending LAPIC INIT event when vCPU is in VMX
operation.

However, current API of KVM_SET_MP_STATE allows userspace to put vCPU
into KVM_MP_STATE_SIPI_RECEIVED or KVM_MP_STATE_INIT_RECEIVED even when
vCPU is in VMX operation.

Fix this by introducing a util method to check if vCPU state latch INIT
signals and use it in KVM_SET_MP_STATE handler.

Fixes: 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states")
Reported-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -2714,7 +2714,7 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 	 * KVM_MP_STATE_INIT_RECEIVED state), just eat SIPIs
 	 * and leave the INIT pending.
 	 */
-	if (is_smm(vcpu) || kvm_x86_ops->apic_init_signal_blocked(vcpu)) {
+	if (kvm_vcpu_latch_init(vcpu)) {
 		WARN_ON_ONCE(vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED);
 		if (test_bit(KVM_APIC_SIPI, &apic->pending_events))
 			clear_bit(KVM_APIC_SIPI, &apic->pending_events);

arch/x86/kvm/x86.c

@@ -8706,8 +8706,12 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 	    mp_state->mp_state != KVM_MP_STATE_RUNNABLE)
 		goto out;
 
-	/* INITs are latched while in SMM */
-	if ((is_smm(vcpu) || vcpu->arch.smi_pending) &&
+	/*
+	 * KVM_MP_STATE_INIT_RECEIVED means the processor is in
+	 * INIT state; latched init should be reported using
+	 * KVM_SET_VCPU_EVENTS, so reject it here.
+	 */
+	if ((kvm_vcpu_latch_init(vcpu) || vcpu->arch.smi_pending) &&
 	    (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED ||
 	     mp_state->mp_state == KVM_MP_STATE_INIT_RECEIVED))
 		goto out;

arch/x86/kvm/x86.h

@@ -258,6 +258,11 @@ static inline bool kvm_check_has_quirk(struct kvm *kvm, u64 quirk)
 	return !(kvm->arch.disabled_quirks & quirk);
 }
 
+static inline bool kvm_vcpu_latch_init(struct kvm_vcpu *vcpu)
+{
+	return is_smm(vcpu) || kvm_x86_ops->apic_init_signal_blocked(vcpu);
+}
+
 void kvm_set_pending_timer(struct kvm_vcpu *vcpu);
 void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip);