KVM: x86: Fixes posted interrupt check for IRQs delivery modes

Current logic incorrectly uses the enum ioapic_irq_destination_types
to check the posted interrupt destination types. However, the value was
set using APIC_DM_XXX macros, which are left-shifted by 8 bits.

Fixes by using the APIC_DM_FIXED and APIC_DM_LOWEST instead.

Fixes: (fdcf7562 'KVM: x86: Disable posted interrupts for non-standard IRQs delivery modes')
Cc: Alexander Graf <graf@amazon.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <1586239989-58305-1-git-send-email-suravee.suthikulpanit@amd.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1663,8 +1663,8 @@ void kvm_set_msi_irq(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *e,
 static inline bool kvm_irq_is_postable(struct kvm_lapic_irq *irq)
 {
 	/* We can only post Fixed and LowPrio IRQs */
-	return (irq->delivery_mode == dest_Fixed ||
-		irq->delivery_mode == dest_LowestPrio);
+	return (irq->delivery_mode == APIC_DM_FIXED ||
+		irq->delivery_mode == APIC_DM_LOWEST);
 }
 
 static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)