target/s390x: Use a 16-bit immediate in VREP

Unlike most other instructions that contain an immediate element index,
VREP's one is 16-bit, and not 4-bit. The code uses only 8 bits, so
using, e.g., 0x101 does not lead to a specification exception.

Fix by checking all 16 bits.

Cc: qemu-stable@nongnu.org
Fixes: 28d0873 ("s390x/tcg: Implement VECTOR REPLICATE")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230807163459.849766-1-iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 23e87d4)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

target/s390x/tcg/translate_vx.c.inc

@@ -57,7 +57,7 @@
 #define FPF_LONG        3
 #define FPF_EXT         4
 
-static inline bool valid_vec_element(uint8_t enr, MemOp es)
+static inline bool valid_vec_element(uint16_t enr, MemOp es)
 {
     return !(enr & ~(NUM_VEC_ELEMENTS(es) - 1));
 }
@@ -1014,7 +1014,7 @@ static DisasJumpType op_vpdi(DisasContext *s, DisasOps *o)
 
 static DisasJumpType op_vrep(DisasContext *s, DisasOps *o)
 {
-    const uint8_t enr = get_field(s, i2);
+    const uint16_t enr = get_field(s, i2);
     const uint8_t es = get_field(s, m4);
 
     if (es > ES_64 || !valid_vec_element(enr, es)) {