[ot] target/riscv: pmp: exit csr writes early if value was not changed

Signed-off-by: Loïc Lefort <[email protected]>
lowRISC · Dec 6, 2023 · a98c7d6 · a98c7d6
1 parent 72c5fa9
commit a98c7d6
Showing 1 changed file with 16 additions and 8 deletions.
diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
@@ -149,6 +149,11 @@ static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index)
 static bool pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
 {
     if (pmp_index < MAX_RISCV_PMPS) {
+        if (env->pmp_state.pmp[pmp_index].cfg_reg == val) {
+            /* no change */
+            return false;
+        }
+
         if (!pmp_is_writable(env, pmp_index)) {
             qemu_log_mask(LOG_GUEST_ERROR,
                           "ignoring pmpcfg[%u] write - locked"
@@ -162,7 +167,7 @@ static bool pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
                           " - current:0x%02x new:0x%02x\n",
                           pmp_index, env->pmp_state.pmp[pmp_index].cfg_reg,
                           val);
-        } else if (env->pmp_state.pmp[pmp_index].cfg_reg != val) {
+        } else {
             env->pmp_state.pmp[pmp_index].cfg_reg = val;
             pmp_update_rule_addr(env, pmp_index);
             return true;
@@ -537,6 +542,11 @@ void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
     bool is_next_cfg_tor = false;
 
     if (addr_index < MAX_RISCV_PMPS) {
+        if (env->pmp_state.pmp[addr_index].addr_reg == val) {
+            /* no change */
+            return;
+        }
+
         /*
          * In TOR mode, need to check the lock bit of the next pmp
          * (if there is a next).
@@ -557,14 +567,12 @@ void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
         }
 
         if (pmp_is_writable(env, addr_index)) {
-            if (env->pmp_state.pmp[addr_index].addr_reg != val) {
-                env->pmp_state.pmp[addr_index].addr_reg = val;
-                pmp_update_rule_addr(env, addr_index);
-                if (is_next_cfg_tor) {
-                    pmp_update_rule_addr(env, addr_index + 1);
-                }
-                tlb_flush(env_cpu(env));
+            env->pmp_state.pmp[addr_index].addr_reg = val;
+            pmp_update_rule_addr(env, addr_index);
+            if (is_next_cfg_tor) {
+                pmp_update_rule_addr(env, addr_index + 1);
             }
+            tlb_flush(env_cpu(env));
         } else {
             qemu_log_mask(LOG_GUEST_ERROR,
                           "ignoring pmpaddr[%u] write - locked"