From: Greentime Hu <greentime.hu@sifive.com>

Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20211210075704.23951-11-frank.chang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/cpu_bits.h | 1 +
 target/riscv/csr.c      | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 8dc6aa62c6..1e31f4d35f 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -63,6 +63,7 @@
 #define CSR_VCSR            0x00f
 #define CSR_VL              0xc20
 #define CSR_VTYPE           0xc21
+#define CSR_VLENB           0xc22
 
 /* VCSR fields */
 #define VCSR_VXSAT_SHIFT    0
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 832ccdcf33..5d1eec1ea0 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -285,6 +285,12 @@ static RISCVException read_vl(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static int read_vlenb(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env_archcpu(env)->cfg.vlen >> 3;
+    return RISCV_EXCP_NONE;
+}
+
 static RISCVException read_vxrm(CPURISCVState *env, int csrno,
                                 target_ulong *val)
 {
@@ -1835,6 +1841,7 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_VCSR]     = { "vcsr",     vs,     read_vcsr,    write_vcsr   },
     [CSR_VL]       = { "vl",       vs,     read_vl                    },
     [CSR_VTYPE]    = { "vtype",    vs,     read_vtype                 },
+    [CSR_VLENB]    = { "vlenb",    vs,     read_vlenb                 },
     /* User Timers and Counters */
     [CSR_CYCLE]    = { "cycle",    ctr,    read_instret  },
     [CSR_INSTRET]  = { "instret",  ctr,    read_instret  },
-- 
2.31.1