KVM: VMX: Don't unblock vCPU w/ Posted IRQ if IRQs are disabled in guest

Don't configure the wakeup handler when a vCPU is blocking with IRQs
disabled, in which case any IRQ, posted or otherwise, should not be
recognized and thus should not wake the vCPU.

Fixes: bf9f6ac8 ("KVM: Update Posted-Interrupts Descriptor when vCPU is blocked")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/posted_intr.c

@@ -147,7 +147,8 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
 	struct pi_desc old, new;
 	struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
 
-	if (!vmx_can_use_vtd_pi(vcpu->kvm))
+	if (!vmx_can_use_vtd_pi(vcpu->kvm) ||
+	    vmx_interrupt_blocked(vcpu))
 		return 0;
 
 	WARN_ON(irqs_disabled());