target/riscv: smstateen check for fcsr

Implement the s/h/mstateen.fcsr bit as defined in the smstateen spec
and check for it when accessing the fcsr register and its fields.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20230518175058.2772506-2-mchitale@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/csr.c

@@ -82,6 +82,10 @@ static RISCVException fs(CPURISCVState *env, int csrno)
         !riscv_cpu_cfg(env)->ext_zfinx) {
         return RISCV_EXCP_ILLEGAL_INST;
     }
+
+    if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
+        return smstateen_acc_ok(env, 0, SMSTATEEN0_FCSR);
+    }
 #endif
     return RISCV_EXCP_NONE;
 }
@@ -2104,6 +2108,9 @@ static RISCVException write_mstateen0(CPURISCVState *env, int csrno,
                                       target_ulong new_val)
 {
     uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
+    if (!riscv_has_ext(env, RVF)) {
+        wr_mask |= SMSTATEEN0_FCSR;
+    }
 
     return write_mstateen(env, csrno, wr_mask, new_val);
 }
@@ -2177,6 +2184,10 @@ static RISCVException write_hstateen0(CPURISCVState *env, int csrno,
 {
     uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
 
+    if (!riscv_has_ext(env, RVF)) {
+        wr_mask |= SMSTATEEN0_FCSR;
+    }
+
     return write_hstateen(env, csrno, wr_mask, new_val);
 }
 
@@ -2263,6 +2274,10 @@ static RISCVException write_sstateen0(CPURISCVState *env, int csrno,
 {
     uint64_t wr_mask = SMSTATEEN_STATEEN | SMSTATEEN0_HSENVCFG;
 
+    if (!riscv_has_ext(env, RVF)) {
+        wr_mask |= SMSTATEEN0_FCSR;
+    }
+
     return write_sstateen(env, csrno, wr_mask, new_val);
 }