bug fix: canonical check on virtual address for data accesses (#2667)

As mentioned in the spec, we need to perform a canonical check on the virtual address for instruction fetch, load, and store. If the check fails, it will cause the page-fault exception.

This PR fixes the above two:
- Changes INSTR_ACCESS_FAULT to INSTR_PAGE_FAULT
- Adding virtual address check on data accesses as well

core/cva6_mmu/cva6_mmu.sv

@@ -133,6 +133,7 @@ module cva6_mmu
   logic iaccess_err;  // insufficient privilege to access this instruction page
   logic i_g_st_access_err;  // insufficient privilege at g stage to access this instruction page
   logic daccess_err;  // insufficient privilege to access this data page
+  logic canonical_addr_check;  // canonical check on the virtual address for SV39
   logic d_g_st_access_err;  // insufficient privilege to access this data page
   logic ptw_active;  // PTW is currently walking a page table
   logic walking_instr;  // PTW is walking because of an ITLB miss
@@ -380,7 +381,7 @@ module cva6_mmu
       // we work with SV39 or SV32, so if VM is enabled, check that all bits [CVA6Cfg.VLEN-1:CVA6Cfg.SV-1] are equal
       if (icache_areq_i.fetch_req && !((&icache_areq_i.fetch_vaddr[CVA6Cfg.VLEN-1:CVA6Cfg.SV-1]) == 1'b1 || (|icache_areq_i.fetch_vaddr[CVA6Cfg.VLEN-1:CVA6Cfg.SV-1]) == 1'b0)) begin
 
-        icache_areq_o.fetch_exception.cause = riscv::INSTR_ACCESS_FAULT;
+        icache_areq_o.fetch_exception.cause = riscv::INSTR_PAGE_FAULT;
         icache_areq_o.fetch_exception.valid = 1'b1;
         if (CVA6Cfg.TvalEn)
           icache_areq_o.fetch_exception.tval = CVA6Cfg.XLEN'(icache_areq_i.fetch_vaddr);
@@ -512,6 +513,10 @@ module cva6_mmu
     lsu_valid_o = lsu_req_q;
     lsu_exception_o = misaligned_ex_i;
 
+    // we work with SV39 or SV32, so if VM is enabled, check that all bits [CVA6Cfg.VLEN-1:CVA6Cfg.SV-1] are equal to bit [CVA6Cfg.SV]
+    canonical_addr_check = (lsu_req_i && en_ld_st_translation_i &&
+           !((&lsu_vaddr_i[CVA6Cfg.VLEN-1:CVA6Cfg.SV-1]) == 1'b1 || (|lsu_vaddr_i[CVA6Cfg.VLEN-1:CVA6Cfg.SV-1]) == 1'b0));
+
     // Check if the User flag is set, then we may only access it in supervisor mode
     // if SUM is enabled
     daccess_err = en_ld_st_translation_i &&
@@ -578,7 +583,7 @@ module cva6_mmu
               lsu_exception_o.tinst = '0;
               lsu_exception_o.gva = ld_st_v_i;
             end
-          end else if ((en_ld_st_translation_i || !CVA6Cfg.RVH) && (!dtlb_pte_q.w || daccess_err || !dtlb_pte_q.d)) begin
+          end else if ((en_ld_st_translation_i || !CVA6Cfg.RVH) && (!dtlb_pte_q.w || daccess_err || canonical_addr_check || !dtlb_pte_q.d)) begin
             lsu_exception_o.cause = riscv::STORE_PAGE_FAULT;
             lsu_exception_o.valid = 1'b1;
             if (CVA6Cfg.TvalEn)
@@ -606,7 +611,7 @@ module cva6_mmu
               lsu_exception_o.gva = ld_st_v_i;
             end
             // check for sufficient access privileges - throw a page fault if necessary
-          end else if (daccess_err) begin
+          end else if (daccess_err || canonical_addr_check) begin
             lsu_exception_o.cause = riscv::LOAD_PAGE_FAULT;
             lsu_exception_o.valid = 1'b1;
             if (CVA6Cfg.TvalEn)