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>
---
 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 03a26fa680c..1df818ec6a6 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 f70b67cce3c..92cf2eedd40 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -264,6 +264,12 @@ static int read_vtype(CPURISCVState *env, int csrno, target_ulong *val)
     return 0;
 }
 
+static int read_vlenb(CPURISCVState *env, int csrno, target_ulong *val)
+{
+    *val = env_archcpu(env)->cfg.vlen >> 3;
+    return 0;
+}
+
 static int read_vl(CPURISCVState *env, int csrno, target_ulong *val)
 {
     *val = env->vl;
@@ -1412,6 +1418,7 @@ 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  },
-- 
2.17.1