[PATCH 4/5] target/riscv: Add MEDELEGH, HEDELEGH csrs for RV32

[Fea.Wang]

Based on privileged spec 1.13, the RV32 needs to implement MEDELEGH
and HEDELEGH for exception codes 32-47 for reserving and exception codes
48-63 for custom use. Add the CSR number though the implementation is
just reading zero and writing ignore. Besides, for accessing HEDELEGH, it
should be controlled by mstateen0 'P1P13' bit.

Signed-off-by: Fea.Wang <fea.wang@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
---
 target/riscv/cpu_bits.h |  2 ++
 target/riscv/csr.c      | 31 +++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 28bd3fb0b4..f888025c59 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -156,6 +156,8 @@
 
 /* 32-bit only */
 #define CSR_MSTATUSH        0x310
+#define CSR_MEDELEGH        0x312
+#define CSR_HEDELEGH        0x612
 
 /* Machine Trap Handling */
 #define CSR_MSCRATCH        0x340
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index d844ce770e..4d7313f456 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -3227,6 +3227,33 @@ static RISCVException write_hedeleg(CPURISCVState *env, 
int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException read_hedelegh(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    RISCVException ret;
+    ret = smstateen_acc_ok(env, 0, SMSTATEEN0_P1P13);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
+    /* Reserved, now read zero */
+    *val = 0;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_hedelegh(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    RISCVException ret;
+    ret = smstateen_acc_ok(env, 0, SMSTATEEN0_P1P13);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
+    /* Reserved, now write ignore */
+    return RISCV_EXCP_NONE;
+}
+
 static RISCVException rmw_hvien64(CPURISCVState *env, int csrno,
                                     uint64_t *ret_val,
                                     uint64_t new_val, uint64_t wr_mask)
@@ -4674,6 +4701,10 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
 
     [CSR_MSTATUSH]    = { "mstatush",   any32, read_mstatush,
                           write_mstatush                                   },
+    [CSR_MEDELEGH]    = { "medelegh",   any32, read_zero, write_ignore,
+                          .min_priv_ver = PRIV_VERSION_1_13_0              },
+    [CSR_HEDELEGH]    = { "hedelegh",   any32, read_hedelegh, write_hedelegh,
+                          .min_priv_ver = PRIV_VERSION_1_13_0              },
 
     /* Machine Trap Handling */
     [CSR_MSCRATCH] = { "mscratch", any,  read_mscratch, write_mscratch,
-- 
2.34.1