target/riscv/cpu_helper.c: Invalid exception on MMU translation stage

According to RISCV privileged spec sect. 5.3.2 Virtual Address Translation Process
access-fault exceptions may raise only after PMA/PMP check. Current implementation
generates an access-fault for mbare mode even if there were no PMA/PMP errors.
This patch removes the erroneous MMU mode check and generates an access-fault
exception based on the pmp_violation flag only.

Fixes: 1448689 ("target/riscv: Allow specifying MMU stage")

Signed-off-by: Ivan Klokov <ivan.klokov@syntacore.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20231121071757.7178-2-ivan.klokov@syntacore.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit 82d53ad)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

target/riscv/cpu_helper.c

@@ -1100,47 +1100,31 @@ static void raise_mmu_exception(CPURISCVState *env, target_ulong address,
                                 bool two_stage_indirect)
 {
     CPUState *cs = env_cpu(env);
-    int page_fault_exceptions, vm;
-    uint64_t stap_mode;
-
-    if (riscv_cpu_mxl(env) == MXL_RV32) {
-        stap_mode = SATP32_MODE;
-    } else {
-        stap_mode = SATP64_MODE;
-    }
-
-    if (first_stage) {
-        vm = get_field(env->satp, stap_mode);
-    } else {
-        vm = get_field(env->hgatp, stap_mode);
-    }
-
-    page_fault_exceptions = vm != VM_1_10_MBARE && !pmp_violation;
 
     switch (access_type) {
     case MMU_INST_FETCH:
         if (env->virt_enabled && !first_stage) {
             cs->exception_index = RISCV_EXCP_INST_GUEST_PAGE_FAULT;
         } else {
-            cs->exception_index = page_fault_exceptions ?
-                RISCV_EXCP_INST_PAGE_FAULT : RISCV_EXCP_INST_ACCESS_FAULT;
+            cs->exception_index = pmp_violation ?
+                RISCV_EXCP_INST_ACCESS_FAULT : RISCV_EXCP_INST_PAGE_FAULT;
         }
         break;
     case MMU_DATA_LOAD:
         if (two_stage && !first_stage) {
             cs->exception_index = RISCV_EXCP_LOAD_GUEST_ACCESS_FAULT;
         } else {
-            cs->exception_index = page_fault_exceptions ?
-                RISCV_EXCP_LOAD_PAGE_FAULT : RISCV_EXCP_LOAD_ACCESS_FAULT;
+            cs->exception_index = pmp_violation ?
+                RISCV_EXCP_LOAD_ACCESS_FAULT : RISCV_EXCP_LOAD_PAGE_FAULT;
         }
         break;
     case MMU_DATA_STORE:
         if (two_stage && !first_stage) {
             cs->exception_index = RISCV_EXCP_STORE_GUEST_AMO_ACCESS_FAULT;
         } else {
-            cs->exception_index = page_fault_exceptions ?
-                RISCV_EXCP_STORE_PAGE_FAULT :
-                RISCV_EXCP_STORE_AMO_ACCESS_FAULT;
+            cs->exception_index = pmp_violation ?
+                RISCV_EXCP_STORE_AMO_ACCESS_FAULT :
+                RISCV_EXCP_STORE_PAGE_FAULT;
         }
         break;
     default: