xen/riscv: implement make_intc_domU_node()

Introduce a RISC-V specific function to create an interrupt controller
Device Tree node for DomU domains during dom0less build.

Add make_intc_domU_node() to the dom0less build path and wire it to
a new generic helper, intc_make_domu_dt_node(), which delegates DT
node creation to the active interrupt controller implementation via
vintc_init_ops.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/riscv/include/asm/domain.h

@@ -97,6 +97,8 @@ struct arch_domain {
     struct paging_domain paging;
 
     const unsigned long *isa;
+
+    struct vintc *vintc;
 };
 
 #include <xen/sched.h>

xen/arch/riscv/include/asm/intc.h

@@ -16,6 +16,7 @@ enum intc_variant {
 
 struct cpu_user_regs;
 struct irq_desc;
+struct kernel_info;
 
 struct intc_info {
     enum intc_variant hw_variant;
@@ -47,6 +48,15 @@ struct intc_hw_init_ops {
     int (*init)(void);
 };
 
+struct vintc_init_ops {
+    /* Create interrupt controller node for domain */
+    int (*make_domu_dt_node)(struct kernel_info *kinfo);
+};
+
+struct vintc {
+    const struct vintc_init_ops *init_ops;
+};
+
 void intc_preinit(void);
 
 void register_intc_ops(const struct intc_hw_init_ops *init_ops);

xen/arch/riscv/intc.c

@@ -3,6 +3,7 @@
 #include <xen/acpi.h>
 #include <xen/bug.h>
 #include <xen/device_tree.h>
+#include <xen/fdt-kernel.h>
 #include <xen/init.h>
 #include <xen/irq.h>
 #include <xen/lib.h>
@@ -72,3 +73,10 @@ void intc_route_irq_to_xen(struct irq_desc *desc, unsigned int priority)
     intc_set_irq_type(desc, desc->arch.type);
     intc_set_irq_priority(desc, priority);
 }
+
+int __init make_intc_domU_node(struct kernel_info *kinfo)
+{
+    const struct vintc *vintc = kinfo->bd.d->arch.vintc;
+
+    return vintc->init_ops->make_domu_dt_node(kinfo);
+}