Add method to probe which memory regions are reservable

Default reservable regions is the same as before

riscv/mmu.cc

@@ -192,6 +192,10 @@ void mmu_t::load_slow_path_intrapage(reg_t addr, reg_t len, uint8_t* bytes, uint
 
   reg_t paddr = translate(addr, len, LOAD, xlate_flags);
 
+  if ((xlate_flags & RISCV_XLATE_LR) && !sim->reservable(paddr)) {
+    throw trap_load_access_fault((proc) ? proc->state.v : false, addr, 0, 0);
+  }
+
   if (auto host_addr = sim->addr_to_mem(paddr)) {
     memcpy(bytes, host_addr, len);
     if (tracer.interested_in_range(paddr, paddr + PGSIZE, LOAD))
@@ -199,12 +203,13 @@ void mmu_t::load_slow_path_intrapage(reg_t addr, reg_t len, uint8_t* bytes, uint
     else if (xlate_flags == 0)
       refill_tlb(addr, paddr, host_addr, LOAD);
 
-    if (xlate_flags & RISCV_XLATE_LR) {
-      load_reservation_address = paddr;
-    }
-  } else if ((xlate_flags & RISCV_XLATE_LR) || !mmio_load(paddr, len, bytes)) {
+  } else if (!mmio_load(paddr, len, bytes)) {
     throw trap_load_access_fault((proc) ? proc->state.v : false, addr, 0, 0);
   }
+
+  if (xlate_flags & RISCV_XLATE_LR) {
+    load_reservation_address = paddr;
+  }
 }
 
 void mmu_t::load_slow_path(reg_t addr, reg_t len, uint8_t* bytes, uint32_t xlate_flags)

riscv/mmu.h

@@ -163,7 +163,7 @@ public:
   void clean_inval(reg_t addr, bool clean, bool inval) {
     convert_load_traps_to_store_traps({
       const reg_t paddr = translate(addr, blocksz, LOAD, 0) & ~(blocksz - 1);
-      if (sim->addr_to_mem(paddr)) {
+      if (sim->reservable(paddr)) {
         if (tracer.interested_in_range(paddr, paddr + PGSIZE, LOAD))
           tracer.clean_invalidate(paddr, blocksz, clean, inval);
       } else {
@@ -185,10 +185,10 @@ public:
     }
 
     reg_t paddr = translate(vaddr, 1, STORE, 0);
-    if (sim->addr_to_mem(paddr))
+    if (sim->reservable(paddr))
       return load_reservation_address == paddr;
     else
-      throw trap_store_access_fault((proc) ? proc->state.v : false, vaddr, 0, 0); // disallow SC to I/O space
+      throw trap_store_access_fault((proc) ? proc->state.v : false, vaddr, 0, 0);
   }
 
   template<typename T>

riscv/simif.h

@@ -11,6 +11,7 @@ class simif_t
 public:
   // should return NULL for MMIO addresses
   virtual char* addr_to_mem(reg_t paddr) = 0;
+  virtual bool reservable(reg_t paddr) { return addr_to_mem(paddr); }
   // used for MMIO addresses
   virtual bool mmio_fetch(reg_t paddr, size_t len, uint8_t* bytes) { return mmio_load(paddr, len, bytes); }
   virtual bool mmio_load(reg_t paddr, size_t len, uint8_t* bytes) = 0;