KVM: PPC: Book3S HV P9: Inject pending xive interrupts at guest entry

If there is a pending xive interrupt, inject it at guest entry (if
MSR[EE] is enabled) rather than take another interrupt when the guest
is entered. If xive is enabled then LPCR[LPES] is set so this behaviour
should be expected.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220303053315.1056880-3-npiggin@gmail.com

arch/powerpc/kvm/book3s_hv.c

@@ -4519,9 +4519,14 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
 
 	if (!nested) {
 		kvmppc_core_prepare_to_enter(vcpu);
-		if (test_bit(BOOK3S_IRQPRIO_EXTERNAL,
-			     &vcpu->arch.pending_exceptions))
+		if (vcpu->arch.shregs.msr & MSR_EE) {
+			if (xive_interrupt_pending(vcpu))
+				kvmppc_inject_interrupt_hv(vcpu,
+						BOOK3S_INTERRUPT_EXTERNAL, 0);
+		} else if (test_bit(BOOK3S_IRQPRIO_EXTERNAL,
+			     &vcpu->arch.pending_exceptions)) {
 			lpcr |= LPCR_MER;
+		}
 	} else if (vcpu->arch.pending_exceptions ||
 		   vcpu->arch.doorbell_request ||
 		   xive_interrupt_pending(vcpu)) {