[PATCH v4 10/13] target/riscv/cpu.h: use 'vlenb' in vext_get_vlmax()

[Daniel Henrique Barboza]

Rename the existing 'sew' variable to 'vsew' for extra clarity.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/cpu.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 05e83c4ac9..71696762e3 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -692,9 +692,16 @@ static inline RISCVMXL riscv_cpu_sxl(CPURISCVState *env)
  */
 static inline uint32_t vext_get_vlmax(RISCVCPU *cpu, target_ulong vtype)
 {
-    uint8_t sew = FIELD_EX64(vtype, VTYPE, VSEW);
+    uint8_t vsew = FIELD_EX64(vtype, VTYPE, VSEW);
     int8_t lmul = sextract32(FIELD_EX64(vtype, VTYPE, VLMUL), 0, 3);
-    return cpu->cfg.vlen >> (sew + 3 - lmul);
+    uint32_t vlen = cpu->cfg.vlenb << 3;
+
+    /*
+     * We need to use 'vlen' instead of 'vlenb' to
+     * preserve the '+ 3' in the formula. Otherwise
+     * we risk a negative shift if vsew < lmul.
+     */
+    return vlen >> (vsew + 3 - lmul);
 }
 
 void cpu_get_tb_cpu_state(CPURISCVState *env, vaddr *pc,
-- 
2.43.0