xen/riscv: route unhandled interrupts to do_unexpected_trap()

Currently, an interrupt cause which is not explicitly handled is silently
ignored, and execution resumes without reporting the fault. This is
incorrect and do_unexpected_trap() should be called in the case of
unhandled interrupt.

Fixes: a8b85fabf6 ("xen/riscv: add external interrupt handling for hypervisor mode")
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/riscv/traps.c

@@ -196,6 +196,7 @@ void do_trap(struct cpu_user_regs *cpu_regs)
         {
             /* Handle interrupt */
             unsigned long icause = cause & ~CAUSE_IRQ_FLAG;
+            bool intr_handled = true;
 
             switch ( icause )
             {
@@ -204,9 +205,11 @@ void do_trap(struct cpu_user_regs *cpu_regs)
                 break;
 
             default:
+                intr_handled = false;
                 break;
             }
 
+            if ( intr_handled )
                 break;
         }