Fix Svukte implementation

- Change polarity of svukte_qualified to match ISA spec
- Avoid address dependence of svukte_qualified, per ISA spec
- Move address check to separate routine

Author: aswaterman

riscv/mmu.cc

@@ -630,28 +630,36 @@ reg_t mmu_t::s2xlate(reg_t gva, reg_t gpa, access_type type, access_type trap_ty
   }
 }
 
-bool mmu_t::check_svukte_qualified(reg_t addr, reg_t mode, bool forced_virt)
+bool mmu_t::svukte_qualified(reg_t mode, bool forced_virt)
 {
   state_t* state = proc->get_state();
 
   if (mode != PRV_U)
-    return true;
+    return false;
 
-  if (proc->extension_enabled('S') && get_field(state->senvcfg->read(), SENVCFG_UKTE)) {
-    if (forced_virt && state->prv == PRV_U) {
-      bool hstatus_hukte = proc->extension_enabled('H') && (get_field(state->hstatus->read(), HSTATUS_HUKTE) == 1);
-      return !hstatus_hukte;
-    }
+  bool ukte = get_field(state->senvcfg->read(), SENVCFG_UKTE);
+  if (forced_virt && state->prv == PRV_U)
+    ukte = get_field(state->hstatus->read(), HSTATUS_HUKTE);
 
-    assert(proc->get_xlen() == 64);
-    if ((addr >> 63) & 1) {
-      return (state->v || forced_virt) && ((state->vsatp->read() & SATP64_MODE) == 0);
-    }
-  }
+  if (!ukte)
+    return false;
+
+  assert(proc->get_xlen() == 64);
+
+  if ((proc->get_state()->satp->readvirt(state->v) & SATP64_MODE) == 0)
+    return false;
 
   return true;
 }
 
+bool mmu_t::svukte_fault(reg_t addr, reg_t mode, bool forced_virt)
+{
+  if (!svukte_qualified(mode, forced_virt))
+    return false;
+
+  return addr >> (proc->get_xlen() - 1);
+}
+
 reg_t mmu_t::walk(mem_access_info_t access_info)
 {
   access_type type = access_info.type;
@@ -674,7 +682,7 @@ reg_t mmu_t::walk(mem_access_info_t access_info)
   if (vm.levels == 0)
     return s2xlate(addr, addr & ((reg_t(2) << (proc->xlen-1))-1), type, type, virt, hlvx, false) & ~page_mask; // zero-extend from xlen
 
-  if (proc->extension_enabled(EXT_SVUKTE) && !check_svukte_qualified(addr, mode, access_info.flags.forced_virt)) {
+  if (proc->extension_enabled(EXT_SVUKTE) && svukte_fault(addr, mode, access_info.flags.forced_virt)) {
     throw_page_fault_exception(virt, addr, type);
   }
 

riscv/mmu.h

@@ -453,7 +453,8 @@ class mmu_t
     check_triggers(operation, address, virt, address, data);
   }
   void check_triggers(triggers::operation_t operation, reg_t address, bool virt, reg_t tval, std::optional<reg_t> data);
-  bool check_svukte_qualified(reg_t addr, reg_t mode, bool forced_virt);
+  bool svukte_qualified(reg_t mode, bool forced_virt);
+  bool svukte_fault(reg_t addr, reg_t mode, bool forced_virt);
   reg_t translate(mem_access_info_t access_info, reg_t len);
 
   reg_t pte_load(reg_t pte_paddr, reg_t addr, bool virt, access_type trap_type, size_t ptesize) {