Index: aplintc.c
===================================================================
RCS file: /cvs/src/sys/arch/arm64/dev/aplintc.c,v
diff -u -p -r1.18 aplintc.c
--- aplintc.c	21 Dec 2022 22:30:42 -0000	1.18
+++ aplintc.c	3 Jul 2025 02:47:30 -0000
@@ -658,10 +658,7 @@ aplintc_send_ipi(struct cpu_info *ci, in
 	if (ci == curcpu() && reason == ARM_IPI_NOP)
 		return;
 
-	/* never overwrite IPI_DDB or IPI_HALT with IPI_NOP */
-	if (reason == ARM_IPI_DDB || reason == ARM_IPI_HALT)
-		sc->sc_ipi_reason[ci->ci_cpuid] = reason;
-	membar_producer();
+	atomic_setbits_int(&sc->sc_ipi_reason[ci->ci_cpuid], 1 << reason);
 
 	sendmask = (ci->ci_mpidr & MPIDR_AFF0);
 	if ((curcpu()->ci_mpidr & MPIDR_AFF1) == (ci->ci_mpidr & MPIDR_AFF1)) {
@@ -678,16 +675,16 @@ void
 aplintc_handle_ipi(struct aplintc_softc *sc)
 {
 	struct cpu_info *ci = curcpu();
+	u_int reasons;
 
-	membar_consumer();
-	if (sc->sc_ipi_reason[ci->ci_cpuid] == ARM_IPI_DDB) {
-		sc->sc_ipi_reason[ci->ci_cpuid] = ARM_IPI_NOP;
+	reasons = atomic_swap_uint(&sc->sc_ipi_reason[ci->ci_cpuid], 0);
+	if (reasons) {
 #ifdef DDB
-		db_enter();
+		if (ISSET(reasons, 1 << ARM_IPI_DDB))
+			db_enter();
 #endif
-	} else if (sc->sc_ipi_reason[ci->ci_cpuid] == ARM_IPI_HALT) {
-		sc->sc_ipi_reason[ci->ci_cpuid] = ARM_IPI_NOP;
-		cpu_halt();
+		if (ISSET(reasons, 1 << ARM_IPI_HALT))
+			cpu_halt();
 	}
 
 	sc->sc_ipi_count.ec_count++;