[PATCH v2] tests/qtest/arm-cpu-features: Add feature setting tests

[Andrew Jones <drjones@redhat.com>]

Some cpu features may be enabled and disabled for all configurations
that support the feature. Let's test that.

A recent regression[*] inspired adding these tests.

[*] '-cpu host,pmu=on' caused a segfault

Based-on: "target/arm: Check supported KVM features globally (not per vCPU)"
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
Note: We need to apply this test change after the Based-on patch is
      applied in order to avoid breaking CI with segfaults.

v2:
  - When a feature is enabled by default set false first [Peter]
  - Add Based-on tag [Peter]
  - Also do the PMU setting test with TCG [drew]
  - Improve commit message [drew]
---
 tests/qtest/arm-cpu-features.c | 38 ++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/tests/qtest/arm-cpu-features.c b/tests/qtest/arm-cpu-features.c
index 469217367661..f7e062c1891e 100644
--- a/tests/qtest/arm-cpu-features.c
+++ b/tests/qtest/arm-cpu-features.c
@@ -159,16 +159,35 @@ static bool resp_get_feature(QDict *resp, const char *feature)
     qobject_unref(_resp);                                              \
 })
 
-#define assert_feature(qts, cpu_type, feature, expected_value)         \
+#define resp_assert_feature(resp, feature, expected_value)             \
 ({                                                                     \
-    QDict *_resp, *_props;                                             \
+    QDict *_props;                                                     \
                                                                        \
-    _resp = do_query_no_props(qts, cpu_type);                          \
     g_assert(_resp);                                                   \
     g_assert(resp_has_props(_resp));                                   \
     _props = resp_get_props(_resp);                                    \
     g_assert(qdict_get(_props, feature));                              \
     g_assert(qdict_get_bool(_props, feature) == (expected_value));     \
+})
+
+#define assert_feature(qts, cpu_type, feature, expected_value)         \
+({                                                                     \
+    QDict *_resp;                                                      \
+                                                                       \
+    _resp = do_query_no_props(qts, cpu_type);                          \
+    g_assert(_resp);                                                   \
+    resp_assert_feature(_resp, feature, expected_value);               \
+    qobject_unref(_resp);                                              \
+})
+
+#define assert_set_feature(qts, cpu_type, feature, value)              \
+({                                                                     \
+    const char *_fmt = (value) ? "{ %s: true }" : "{ %s: false }";     \
+    QDict *_resp;                                                      \
+                                                                       \
+    _resp = do_query(qts, cpu_type, _fmt, feature);                    \
+    g_assert(_resp);                                                   \
+    resp_assert_feature(_resp, feature, value);                        \
     qobject_unref(_resp);                                              \
 })
 
@@ -424,10 +443,14 @@ static void test_query_cpu_model_expansion(const void *data)
     assert_error(qts, "host", "The CPU type 'host' requires KVM", NULL);
 
     /* Test expected feature presence/absence for some cpu types */
-    assert_has_feature_enabled(qts, "max", "pmu");
     assert_has_feature_enabled(qts, "cortex-a15", "pmu");
     assert_has_not_feature(qts, "cortex-a15", "aarch64");
 
+    /* Enabling and disabling pmu should always work. */
+    assert_has_feature_enabled(qts, "max", "pmu");
+    assert_set_feature(qts, "max", "pmu", false);
+    assert_set_feature(qts, "max", "pmu", true);
+
     assert_has_not_feature(qts, "max", "kvm-no-adjvtime");
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
@@ -464,7 +487,10 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         return;
     }
 
+    /* Enabling and disabling kvm-no-adjvtime should always work. */
     assert_has_feature_disabled(qts, "host", "kvm-no-adjvtime");
+    assert_set_feature(qts, "host", "kvm-no-adjvtime", true);
+    assert_set_feature(qts, "host", "kvm-no-adjvtime", false);
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
         bool kvm_supports_sve;
@@ -475,7 +501,11 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         char *error;
 
         assert_has_feature_enabled(qts, "host", "aarch64");
+
+        /* Enabling and disabling pmu should always work. */
         assert_has_feature_enabled(qts, "host", "pmu");
+        assert_set_feature(qts, "host", "pmu", false);
+        assert_set_feature(qts, "host", "pmu", true);
 
         assert_error(qts, "cortex-a15",
             "We cannot guarantee the CPU type 'cortex-a15' works "
-- 
2.25.4