arm/acpi: Fix event-channel interrupt when booting with ACPI

Store the event-channel interrupt number and flag in HVM parameter
HVM_PARAM_CALLBACK_IRQ. Then Dom0 could get it through hypercall
HVMOP_get_param.

Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>

xen/arch/arm/domain_build.c

@@ -2050,6 +2050,7 @@ static void initrd_load(struct kernel_info *kinfo)
 static void evtchn_fixup(struct domain *d, struct kernel_info *kinfo)
 {
     int res, node;
+    u64 val;
     gic_interrupt_t intr;
 
     /*
@@ -2065,6 +2066,19 @@ static void evtchn_fixup(struct domain *d, struct kernel_info *kinfo)
     printk("Allocating PPI %u for event channel interrupt\n",
            d->arch.evtchn_irq);
 
+    /* Set the value of domain param HVM_PARAM_CALLBACK_IRQ */
+    val = (u64)HVM_PARAM_CALLBACK_TYPE_PPI << 56;
+    val |= (2 << 8); /* Active-low level-sensitive  */
+    val |= d->arch.evtchn_irq & 0xff;
+    d->arch.hvm_domain.params[HVM_PARAM_CALLBACK_IRQ] = val;
+
+    /*
+     * When booting Dom0 using ACPI, Dom0 can only get the event channel
+     * interrupt via hypercall.
+     */
+    if ( !acpi_disabled )
+        return;
+
     /* Fix up "interrupts" in /hypervisor node */
     node = fdt_path_offset(kinfo->fdt, "/hypervisor");
     if ( node < 0 )