target/arm/cpu64: max cpu: Support sve properties with KVM

Extend the SVE vq map initialization and validation with KVM's
supported vector lengths when KVM is enabled. In order to determine
and select supported lengths we add two new KVM functions for getting
and setting the KVM_REG_ARM64_SVE_VLS pseudo-register.

This patch has been co-authored with Richard Henderson, who reworked
the target/arm/cpu64.c changes in order to push all the validation and
auto-enabling/disabling steps into the finalizer, resulting in a nice
LOC reduction.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Message-id: 20191031142734.8590-9-drjones@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 102 insertions, 2 deletions

diff --git a/tests/arm-cpu-features.c b/tests/arm-cpu-features.c
index a48f9107dd..ffdbc3fce6 100644
--- a/tests/arm-cpu-features.c
+++ b/tests/arm-cpu-features.c
@@ -130,6 +130,17 @@ static QDict *resp_get_props(QDict *resp)
     return qdict;
 }
 
+static bool resp_get_feature(QDict *resp, const char *feature)
+{
+    QDict *props;
+
+    g_assert(resp);
+    g_assert(resp_has_props(resp));
+    props = resp_get_props(resp);
+    g_assert(qdict_get(props, feature));
+    return qdict_get_bool(props, feature);
+}
+
 #define assert_has_feature(qts, cpu_type, feature)                     \
 ({                                                                     \
     QDict *_resp = do_query_no_props(qts, cpu_type);                   \
@@ -359,6 +370,25 @@ static void sve_tests_sve_off(const void *data)
     qtest_quit(qts);
 }
 
+static void sve_tests_sve_off_kvm(const void *data)
+{
+    QTestState *qts;
+
+    qts = qtest_init(MACHINE_KVM "-cpu max,sve=off");
+
+    /*
+     * We don't know if this host supports SVE so we don't
+     * attempt to test enabling anything. We only test that
+     * everything is disabled (as it should be with sve=off)
+     * and that using sve<N>=off to explicitly disable vector
+     * lengths is OK too.
+     */
+    assert_sve_vls(qts, "max", 0, NULL);
+    assert_sve_vls(qts, "max", 0, "{ 'sve128': false }");
+
+    qtest_quit(qts);
+}
+
 static void test_query_cpu_model_expansion(const void *data)
 {
     QTestState *qts;
@@ -414,14 +444,82 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
     }
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
+        bool kvm_supports_sve;
+        char max_name[8], name[8];
+        uint32_t max_vq, vq;
+        uint64_t vls;
+        QDict *resp;
+        char *error;
+
         assert_has_feature(qts, "host", "aarch64");
         assert_has_feature(qts, "host", "pmu");
 
-        assert_has_feature(qts, "max", "sve");
-
         assert_error(qts, "cortex-a15",
             "We cannot guarantee the CPU type 'cortex-a15' works "
             "with KVM on this host", NULL);
+
+        assert_has_feature(qts, "max", "sve");
+        resp = do_query_no_props(qts, "max");
+        kvm_supports_sve = resp_get_feature(resp, "sve");
+        vls = resp_get_sve_vls(resp);
+        qobject_unref(resp);
+
+        if (kvm_supports_sve) {
+            g_assert(vls != 0);
+            max_vq = 64 - __builtin_clzll(vls);
+            sprintf(max_name, "sve%d", max_vq * 128);
+
+            /* Enabling a supported length is of course fine. */
+            assert_sve_vls(qts, "max", vls, "{ %s: true }", max_name);
+
+            /* Get the next supported length smaller than max-vq. */
+            vq = 64 - __builtin_clzll(vls & ~BIT_ULL(max_vq - 1));
+            if (vq) {
+                /*
+                 * We have at least one length smaller than max-vq,
+                 * so we can disable max-vq.
+                 */
+                assert_sve_vls(qts, "max", (vls & ~BIT_ULL(max_vq - 1)),
+                               "{ %s: false }", max_name);
+
+                /*
+                 * Smaller, supported vector lengths cannot be disabled
+                 * unless all larger, supported vector lengths are also
+                 * disabled.
+                 */
+                sprintf(name, "sve%d", vq * 128);
+                error = g_strdup_printf("cannot disable %s", name);
+                assert_error(qts, "max", error,
+                             "{ %s: true, %s: false }",
+                             max_name, name);
+                g_free(error);
+            }
+
+            /*
+             * The smallest, supported vector length is required, because
+             * we need at least one vector length enabled.
+             */
+            vq = __builtin_ffsll(vls);
+            sprintf(name, "sve%d", vq * 128);
+            error = g_strdup_printf("cannot disable %s", name);
+            assert_error(qts, "max", error, "{ %s: false }", name);
+            g_free(error);
+
+            /* Get an unsupported length. */
+            for (vq = 1; vq <= max_vq; ++vq) {
+                if (!(vls & BIT_ULL(vq - 1))) {
+                    break;
+                }
+            }
+            if (vq <= SVE_MAX_VQ) {
+                sprintf(name, "sve%d", vq * 128);
+                error = g_strdup_printf("cannot enable %s", name);
+                assert_error(qts, "max", error, "{ %s: true }", name);
+                g_free(error);
+            }
+        } else {
+            g_assert(vls == 0);
+        }
     } else {
         assert_has_not_feature(qts, "host", "aarch64");
         assert_has_not_feature(qts, "host", "pmu");
@@ -454,6 +552,8 @@ int main(int argc, char **argv)
                             NULL, sve_tests_sve_max_vq_8);
         qtest_add_data_func("/arm/max/query-cpu-model-expansion/sve-off",
                             NULL, sve_tests_sve_off);
+        qtest_add_data_func("/arm/kvm/query-cpu-model-expansion/sve-off",
+                            NULL, sve_tests_sve_off_kvm);
     }
 
     return g_test_run();