[PATCH v6 2/5] target/riscv: smstateen check for h/senvcfg

[Mayuresh Chitale <mchitale@ventanamicro.com>]

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 | 100 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 93 insertions(+), 7 deletions(-)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 27032a416c..ab06b117f9 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -40,6 +40,55 @@ void riscv_set_csr_ops(int csrno, riscv_csr_operations *ops)
 }
 
 /* Predicates */
+#if !defined(CONFIG_USER_ONLY)
+static RISCVException smstateen_acc_ok(CPURISCVState *env, int index,
+                                       uint64_t bit)
+{
+    bool virt = riscv_cpu_virt_enabled(env);
+    CPUState *cs = env_cpu(env);
+    RISCVCPU *cpu = RISCV_CPU(cs);
+    uint64_t hstateen = env->hstateen[index];
+    uint64_t sstateen = env->sstateen[index];
+
+    if (env->priv == PRV_M || !cpu->cfg.ext_smstateen) {
+        return RISCV_EXCP_NONE;
+    }
+
+    if (!(env->mstateen[index] & bit)) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
+
+    /*
+     * Treat hstateen and sstateen as read-only zero if mstateen0.staten
+     * is clear.
+     */
+    if (!(env->mstateen[index] & SMSTATEEN_STATEN)) {
+        hstateen = 0;
+        sstateen = 0;
+    }
+
+    if (virt) {
+        if (!(hstateen & bit)) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        }
+        /*
+         * Treat sstateen as read-only zero if hstateen0.staten is clear.
+         */
+        if (!(hstateen & SMSTATEEN_STATEN)) {
+            sstateen = 0;
+        }
+    }
+
+    if (env->priv == PRV_U && riscv_has_ext(env, RVS)) {
+        if (!(sstateen & bit)) {
+            return RISCV_EXCP_ILLEGAL_INST;
+        }
+    }
+
+    return RISCV_EXCP_NONE;
+}
+#endif
+
 static RISCVException fs(CPURISCVState *env, int csrno)
 {
 #if !defined(CONFIG_USER_ONLY)
@@ -1708,6 +1757,13 @@ 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, 0, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
     *val = env->senvcfg;
     return RISCV_EXCP_NONE;
 }
@@ -1716,15 +1772,27 @@ 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, 0, 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, 0, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
     *val = env->henvcfg;
     return RISCV_EXCP_NONE;
 }
@@ -1733,6 +1801,12 @@ 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, 0, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
 
     if (riscv_cpu_mxl(env) == MXL_RV64) {
         mask |= HENVCFG_PBMTE | HENVCFG_STCE;
@@ -1746,6 +1820,13 @@ 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, 0, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
     *val = env->henvcfg >> 32;
     return RISCV_EXCP_NONE;
 }
@@ -1755,9 +1836,14 @@ 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, 0, SMSTATEEN0_HSENVCFG);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
 
+    env->henvcfg = (env->henvcfg & ~mask) | (valh & mask);
     return RISCV_EXCP_NONE;
 }
 
@@ -1789,7 +1875,7 @@ static RISCVException write_mstateen(CPURISCVState *env, int csrno,
 static RISCVException write_mstateen0(CPURISCVState *env, int csrno,
                                       target_ulong new_val)
 {
-    uint64_t wr_mask = SMSTATEEN_STATEN;
+    uint64_t wr_mask = SMSTATEEN_STATEN | SMSTATEEN0_HSENVCFG;
 
     return write_mstateen(env, csrno, wr_mask, new_val);
 }
@@ -1836,7 +1922,7 @@ static RISCVException write_mstateenh(CPURISCVState *env, int csrno,
 static RISCVException write_mstateen0h(CPURISCVState *env, int csrno,
                                       target_ulong new_val)
 {
-    uint64_t wr_mask = SMSTATEEN_STATEN;
+    uint64_t wr_mask = SMSTATEEN_STATEN | SMSTATEEN0_HSENVCFG;
 
     return write_mstateenh(env, csrno, wr_mask, new_val);
 }
@@ -1885,7 +1971,7 @@ static RISCVException write_hstateen(CPURISCVState *env, int csrno,
 static RISCVException write_hstateen0(CPURISCVState *env, int csrno,
                                       target_ulong new_val)
 {
-    uint64_t wr_mask = SMSTATEEN_STATEN;
+    uint64_t wr_mask = SMSTATEEN_STATEN | SMSTATEEN0_HSENVCFG;
 
     return write_hstateen(env, csrno, wr_mask, new_val);
 }
@@ -1936,7 +2022,7 @@ static RISCVException write_hstateenh(CPURISCVState *env, int csrno,
 static RISCVException write_hstateen0h(CPURISCVState *env, int csrno,
                                        target_ulong new_val)
 {
-    uint64_t wr_mask = SMSTATEEN_STATEN;
+    uint64_t wr_mask = SMSTATEEN_STATEN | SMSTATEEN0_HSENVCFG;
 
     return write_hstateenh(env, csrno, wr_mask, new_val);
 }
@@ -1995,7 +2081,7 @@ static RISCVException write_sstateen(CPURISCVState *env, int csrno,
 static RISCVException write_sstateen0(CPURISCVState *env, int csrno,
                                       target_ulong new_val)
 {
-    uint64_t wr_mask = SMSTATEEN_STATEN;
+    uint64_t wr_mask = SMSTATEEN_STATEN | SMSTATEEN0_HSENVCFG;
 
     return write_sstateen(env, csrno, wr_mask, new_val);
 }
-- 
2.25.1