Add svnapot extention support

model/riscv_vmem.sail

@@ -164,7 +164,30 @@ function pt_walk(sv_params,
                 }
               }
               else {
+                let mask_bits = level * sv_params.pte_PPN_j_size_bits;
+                let mask : bits(64) = ~ (ones() << mask_bits);
+                let ppn : bits(64) = ppns | (vpns_of_va(sv_params, va) & mask);
+                let napot_mask : bits(64) = ppn ^ (ppn - 1);
+                let napot_mask_not : bits(64) = ~ (napot_mask);
+                let ptshift_level = sv_params.levels - 1;
+                let ptshift = ptshift_level * sv_params.vpn_size_bits;
+
+                let page_base = (ppn & napot_mask_not) | 
+                                (vpns_of_va(sv_params, va) & napot_mask) | 
+                                (vpns_of_va(sv_params, va) & ((zero_extend(0b1) << ptshift) - zero_extend(0b1)));
+
                 let pa = (ppns << pagesize_bits) | zero_extend(offset_of_va(va));
+                let pa_napot = page_base << 12 | zero_extend(offset_of_va(va));
+
+                // For svnapot ext purpose.
+                if (pte & (zero_extend(0b1) << 63)) == (zero_extend(0b1) << 63) then {
+                  if (napot_mask != zero_extend(0xf)) then {
+                    return PTW_Failure(PTW_Invalid_PTE(), ext_ptw)
+                  } else {
+                    return PTW_Success(pa_napot, pte, pte_addr, level, global', ext_ptw)
+                  }
+                };
+
                 PTW_Success(pa, pte, pte_addr, level, global', ext_ptw)
               }
           }

model/riscv_vmem_ptw.sail

@@ -15,13 +15,14 @@
 // Failure modes for address-translation/page-table-walks
 // PRIVATE
 union PTW_Error = {
-  PTW_Invalid_Addr  : unit,          // invalid source address
-  PTW_Access        : unit,          // physical memory access error for a PTE
-  PTW_Invalid_PTE   : unit,
-  PTW_No_Permission : unit,
-  PTW_Misaligned    : unit,          // misaligned superpage
-  PTW_PTE_Update    : unit,          // PTE update needed but not enabled
-  PTW_Ext_Error     : ext_ptw_error  // parameterized for errors from extensions
+  PTW_Invalid_Addr    : unit,          // invalid source address
+  PTW_Access          : unit,          // physical memory access error for a PTE
+  PTW_Invalid_PTE     : unit,
+  PTW_No_Permission   : unit,
+  PTW_Misaligned      : unit,          // misaligned superpage
+  PTW_PTE_Update      : unit,          // PTE update needed but not enabled
+  PTW_Ext_Error       : ext_ptw_error, // parameterized for errors from extensions
+  PTW_Unsupport_Napot : unit           // Unsupport Napot bits
 }
 
 // PRIVATE: only 'to_str' overload is public
@@ -33,7 +34,8 @@ function ptw_error_to_str(e : PTW_Error) -> string = {
     PTW_No_Permission()  => "no-permission",
     PTW_Misaligned()     => "misaligned-superpage",
     PTW_PTE_Update()     => "pte-update-needed",
-    PTW_Ext_Error(e)     => "extension-error"
+    PTW_Ext_Error(e)     => "extension-error",
+    PTW_Unsupport_Napot()=> "unsupport napot bits"
   }
 }