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>
---
 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 7afdd4814bb..fe055b67a6a 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 ca85a54a0f1..11ce6d4576a 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -188,6 +188,12 @@ 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;
@@ -1292,6 +1298,7 @@ static riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_VCSR] =                { vs,   read_vcsr,        write_vcsr        },
     [CSR_VL] =                  { vs,   read_vl                             },
     [CSR_VTYPE] =               { vs,   read_vtype                          },
+    [CSR_VLENB] =               { vs,   read_vlenb                          },
     /* User Timers and Counters */
     [CSR_CYCLE] =               { ctr,  read_instret                        },
     [CSR_INSTRET] =             { ctr,  read_instret                        },
-- 
2.17.1