[RFC PATCH v4 2/4] target/riscv: smstateen check for h/senvcfg

[Mayuresh Chitale]

Accesses to henvcfg, henvcfgh and senvcfg are allowed
only if corresponding bit in mstateen0/hstateen0 is
enabled. Otherwise an illegal instruction trap is
generated.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
---
 target/riscv/csr.c | 84 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 78 insertions(+), 6 deletions(-)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index fea5cdd178..d4920b3fa4 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -39,6 +39,37 @@ void riscv_set_csr_ops(int csrno, riscv_csr_operations *ops)
 }
 
 /* Predicates */
+static RISCVException smstateen_acc_ok(CPURISCVState *env, int mode, int bit)
+{
+    CPUState *cs = env_cpu(env);
+    RISCVCPU *cpu = RISCV_CPU(cs);
+    bool virt = riscv_cpu_virt_enabled(env);
+
+    if (!cpu->cfg.ext_smstateen) {
+        return RISCV_EXCP_NONE;
+    }
+
+#if !defined(CONFIG_USER_ONLY)
+    if (!(env->mstateen[0] & 1UL << bit)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    if (virt) {
+        if (!(env->hstateen[0] & 1UL << bit)) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        }
+    }
+
+    if (mode == PRV_U) {
+        if (!(env->sstateen[0] & 1UL << bit)) {
+            return RISCV_EXCP_ILLEGAL_INST;
+        }
+    }
+#endif
+
+    return RISCV_EXCP_NONE;
+}
+
 static RISCVException fs(CPURISCVState *env, int csrno)
 {
 #if !defined(CONFIG_USER_ONLY)
@@ -1557,6 +1588,13 @@ static RISCVException write_menvcfgh(CPURISCVState *env, 
int csrno,
 static RISCVException read_senvcfg(CPURISCVState *env, int csrno,
                                  target_ulong *val)
 {
+    RISCVException ret;
+
+    ret = smstateen_acc_ok(env, PRV_S, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
     *val = env->senvcfg;
     return RISCV_EXCP_NONE;
 }
@@ -1565,15 +1603,27 @@ static RISCVException write_senvcfg(CPURISCVState *env, 
int csrno,
                                   target_ulong val)
 {
     uint64_t mask = SENVCFG_FIOM | SENVCFG_CBIE | SENVCFG_CBCFE | SENVCFG_CBZE;
+    RISCVException ret;
 
-    env->senvcfg = (env->senvcfg & ~mask) | (val & mask);
+    ret = smstateen_acc_ok(env, PRV_S, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
 
+    env->senvcfg = (env->senvcfg & ~mask) | (val & mask);
     return RISCV_EXCP_NONE;
 }
 
 static RISCVException read_henvcfg(CPURISCVState *env, int csrno,
                                  target_ulong *val)
 {
+    RISCVException ret;
+
+    ret = smstateen_acc_ok(env, PRV_S, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
     *val = env->henvcfg;
     return RISCV_EXCP_NONE;
 }
@@ -1582,6 +1632,12 @@ static RISCVException write_henvcfg(CPURISCVState *env, 
int csrno,
                                   target_ulong val)
 {
     uint64_t mask = HENVCFG_FIOM | HENVCFG_CBIE | HENVCFG_CBCFE | HENVCFG_CBZE;
+    RISCVException ret;
+
+    ret = smstateen_acc_ok(env, PRV_S, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
 
     if (riscv_cpu_mxl(env) == MXL_RV64) {
         mask |= HENVCFG_PBMTE | HENVCFG_STCE;
@@ -1595,6 +1651,13 @@ static RISCVException write_henvcfg(CPURISCVState *env, 
int csrno,
 static RISCVException read_henvcfgh(CPURISCVState *env, int csrno,
                                  target_ulong *val)
 {
+    RISCVException ret;
+
+    ret = smstateen_acc_ok(env, PRV_S, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
     *val = env->henvcfg >> 32;
     return RISCV_EXCP_NONE;
 }
@@ -1604,9 +1667,14 @@ static RISCVException write_henvcfgh(CPURISCVState *env, 
int csrno,
 {
     uint64_t mask = HENVCFG_PBMTE | HENVCFG_STCE;
     uint64_t valh = (uint64_t)val << 32;
+    RISCVException ret;
 
-    env->henvcfg = (env->henvcfg & ~mask) | (valh & mask);
+    ret = smstateen_acc_ok(env, PRV_S, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
 
+    env->henvcfg = (env->henvcfg & ~mask) | (valh & mask);
     return RISCV_EXCP_NONE;
 }
 
@@ -1628,7 +1696,8 @@ static RISCVException write_mstateen(CPURISCVState *env, 
int csrno,
                                      target_ulong new_val)
 {
     uint64_t *reg;
-    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
+    uint64_t wr_mask = (1UL << SMSTATEEN_STATEN) |
+                       (1UL << SMSTATEEN0_HSENVCFG);
 
     reg = &env->mstateen[csrno - CSR_MSTATEEN0];
     write_smstateen(env, reg, wr_mask, new_val);
@@ -1649,7 +1718,8 @@ static RISCVException write_mstateenh(CPURISCVState *env, 
int csrno,
 {
     uint64_t *reg;
     uint64_t val;
-    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
+    uint64_t wr_mask = (1UL << SMSTATEEN_STATEN) |
+                       (1UL << SMSTATEEN0_HSENVCFG);
 
     reg = &env->mstateen[csrno - CSR_MSTATEEN0H];
     val = (uint64_t)new_val << 32;
@@ -1671,7 +1741,8 @@ static RISCVException write_hstateen(CPURISCVState *env, 
int csrno,
                                      target_ulong new_val)
 {
     uint64_t *reg;
-    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
+    uint64_t wr_mask = (1UL << SMSTATEEN_STATEN) |
+                       (1UL << SMSTATEEN0_HSENVCFG);
     int index = csrno - CSR_HSTATEEN0;
 
     reg = &env->hstateen[index];
@@ -1694,8 +1765,9 @@ static RISCVException write_hstateenh(CPURISCVState *env, 
int csrno,
 {
     uint64_t *reg;
     uint64_t val;
-    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
     int index = csrno - CSR_HSTATEEN0H;
+    uint64_t wr_mask = (1UL << SMSTATEEN_STATEN) |
+                       (1UL << SMSTATEEN0_HSENVCFG);
 
     reg = &env->hstateen[index];
     val = (uint64_t)new_val << 32;
-- 
2.25.1