[Stable-7.2.5 10/14] target/s390x: Make MC raise specification exception when class >= 16

[Michael Tokarev]

From: Ilya Leoshkevich <iii@linux.ibm.com>

MC requires bit positions 8-11 (upper 4 bits of class) to be zeros,
otherwise it must raise a specification exception.

Cc: qemu-stable@nongnu.org
Fixes: 20d143e2cab8 ("s390x/tcg: Implement MONITOR CALL")
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230724082032.66864-6-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 9c028c057adce49304c6e4a51f6b426bd4f8f6b8)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: context edit in target/s390x/tcg/translate.c)

diff --git a/target/s390x/tcg/excp_helper.c b/target/s390x/tcg/excp_helper.c
index fe02d82201..7094020dcd 100644
--- a/target/s390x/tcg/excp_helper.c
+++ b/target/s390x/tcg/excp_helper.c
@@ -638,7 +638,7 @@ void monitor_event(CPUS390XState *env,
 void HELPER(monitor_call)(CPUS390XState *env, uint64_t monitor_code,
                           uint32_t monitor_class)
 {
-    g_assert(monitor_class <= 0xff);
+    g_assert(monitor_class <= 0xf);
 
     if (env->cregs[8] & (0x8000 >> monitor_class)) {
         monitor_event(env, monitor_code, monitor_class, GETPC());
diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c
index 0c6e0a1bd0..ff64d6c28f 100644
--- a/target/s390x/tcg/translate.c
+++ b/target/s390x/tcg/translate.c
@@ -3350,9 +3350,9 @@ static DisasJumpType op_mc(DisasContext *s, DisasOps *o)
 #if !defined(CONFIG_USER_ONLY)
     TCGv_i32 i2;
 #endif
-    const uint16_t monitor_class = get_field(s, i2);
+    const uint8_t monitor_class = get_field(s, i2);
 
-    if (monitor_class & 0xff00) {
+    if (monitor_class & 0xf0) {
         gen_program_exception(s, PGM_SPECIFICATION);
         return DISAS_NORETURN;
     }
-- 
2.39.2