[PATCH v2 2/2] target/s390x: mark feats dependent on deprecated feats as deprecated

[Collin Walling <walling@linux.ibm.com>]

There are certain CPU model features that depend on other features
that are flagged for deprecation. For example `ineff_nc_tx` depends
on the `te` deprecated feature.

If a user defines a VM with the current list of deprecated features
disabled, the following warning occurs:

	warning: 'ineff_nc_tx' requires 'te'

To alleviate this, add these "dependent features" to the deprecated
features list. This allows the user to see *all* features that should
be disabled to ensure a successful migration to a host system that
may not support certain deprecated features.

Fixes: 6e55b32d45 ("target/s390x: flag te and cte as deprecated")
Signed-off-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
---
 target/s390x/cpu_features.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index 20f9947c7be..babee7f5bac 100644
--- a/target/s390x/cpu_features.c
+++ b/target/s390x/cpu_features.c
@@ -360,10 +360,23 @@ void s390_get_deprecated_features(S390FeatBitmap features)
          S390_FEAT_TRANSACTIONAL_EXE
     };
     int i;
+    bool restart;
 
     for (i = 0; i < ARRAY_SIZE(feats); i++) {
         set_bit(feats[i], features);
     }
+
+    /* Mark features that depend on any deprecated feature */
+    do {
+        restart = false;
+        for (i = 0; i < s390_feat_deps_len; i++) {
+            if (test_bit(s390_feat_deps[i][1], features) &&
+                !test_and_set_bit(s390_feat_deps[i][0], features)) {
+                /* Restart in case set features have other dependencies */
+                restart = true;
+            }
+        }
+    } while (restart);
 }
 
 #define FEAT_GROUP_INIT(_name, _group, _desc)        \
-- 
2.55.0