hw/intc/loongarch_pch: fix edge triggered irq handling

For edge triggered irq, qemu_irq_pulse is used to inject irq. It will
set irq with high level and low level soon to simluate pulse irq.

For edge triggered irq, irq is injected and set as pending at rising
level, do not clear irq at lowering level. LoongArch pch interrupt will
clear irq for lowering level irq, there will be problem. ACPI ged deivce
is edge-triggered irq, it is used for cpu/memory hotplug.

This patch fixes memory hotplug issue on LoongArch virt machine.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230707091557.1474790-1-maobibo@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>

hw/intc/loongarch_pch_pic.c

@@ -30,7 +30,11 @@ static void pch_pic_update_irq(LoongArchPCHPIC *s, uint64_t mask, int level)
             qemu_set_irq(s->parent_irq[s->htmsi_vector[irq]], 1);
         }
     } else {
-        val = mask & s->intisr;
+        /*
+         * intirr means requested pending irq
+         * do not clear pending irq for edge-triggered on lowering edge
+         */
+        val = mask & s->intisr & ~s->intirr;
         if (val) {
             irq = ctz64(val);
             s->intisr &= ~MAKE_64BIT_MASK(irq, 1);
@@ -51,6 +55,7 @@ static void pch_pic_irq_handler(void *opaque, int irq, int level)
         /* Edge triggered */
         if (level) {
             if ((s->last_intirr & mask) == 0) {
+                /* marked pending on a rising edge */
                 s->intirr |= mask;
             }
             s->last_intirr |= mask;