AIA: Take interrupts at VS level through vstopi instead of vsip and vsie

An interrupt is pending at VS level if and only if vstopi is not 0.

The modification is backward compatible because hvictl is implicitly 0
without AIA.

riscv/processor.cc

@@ -907,9 +907,11 @@ reg_t processor_t::select_an_interrupt_with_default_priority(reg_t enabled_inter
 void processor_t::take_interrupt(reg_t pending_interrupts)
 {
   const reg_t s_pending_interrupts = state.nonvirtual_sip->read() & state.nonvirtual_sie->read();
+  const reg_t vstopi = state.vstopi->read();
+  const reg_t vs_pending_interrupt = vstopi ? ((reg_t(1) << get_field(vstopi, MTOPI_IID)) << 1) : 0; // SSIP -> VSSIP, etc
 
   // Do nothing if no pending interrupts
-  if (!pending_interrupts && !s_pending_interrupts) {
+  if (!pending_interrupts && !s_pending_interrupts && !vs_pending_interrupt == 0) {
     return;
   }
 
@@ -928,9 +930,8 @@ void processor_t::take_interrupt(reg_t pending_interrupts)
     enabled_interrupts = s_pending_interrupts & deleg_to_hs & -hs_enabled;
     if (state.v && enabled_interrupts == 0) {
       // VS-ints have least priority and can only be taken with virt enabled
-      const reg_t deleg_to_vs = state.hideleg->read();
       const reg_t vs_enabled = state.prv < PRV_S || (state.prv == PRV_S && sie);
-      enabled_interrupts = pending_interrupts & deleg_to_vs & -vs_enabled;
+      enabled_interrupts = vs_pending_interrupt & -vs_enabled;
     }
   }