[PATCH v6 3/9] target/arm: Allow SVE to be disabled via a CPU property

[Andrew Jones <drjones@redhat.com>]

Since 97a28b0eeac14 ("target/arm: Allow VFP and Neon to be disabled via
a CPU property") we can disable the 'max' cpu model's VFP and neon
features, but there's no way to disable SVE. Add the 'sve=on|off'
property to give it that flexibility. We also rename
cpu_max_get/set_sve_vq to cpu_max_get/set_sve_max_vq in order for them
to follow the typical *_get/set_<property-name> pattern.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
---
 target/arm/cpu.c         |  3 ++-
 target/arm/cpu64.c       | 52 ++++++++++++++++++++++++++++++++++------
 target/arm/monitor.c     |  2 +-
 tests/arm-cpu-features.c |  1 +
 4 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 13813fb21354..2a1e95e90df3 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -200,7 +200,8 @@ static void arm_cpu_reset(CPUState *s)
         env->cp15.cpacr_el1 = deposit64(env->cp15.cpacr_el1, 16, 2, 3);
         env->cp15.cptr_el[3] |= CPTR_EZ;
         /* with maximum vector length */
-        env->vfp.zcr_el[1] = cpu->sve_max_vq - 1;
+        env->vfp.zcr_el[1] = cpu_isar_feature(aa64_sve, cpu) ?
+                             cpu->sve_max_vq - 1 : 0;
         env->vfp.zcr_el[2] = env->vfp.zcr_el[1];
         env->vfp.zcr_el[3] = env->vfp.zcr_el[1];
         /*
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index d7f5bf610a7d..89a8ae77fe84 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -256,15 +256,23 @@ static void aarch64_a72_initfn(Object *obj)
     define_arm_cp_regs(cpu, cortex_a72_a57_a53_cp_reginfo);
 }
 
-static void cpu_max_get_sve_vq(Object *obj, Visitor *v, const char *name,
-                               void *opaque, Error **errp)
+static void cpu_max_get_sve_max_vq(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     ARMCPU *cpu = ARM_CPU(obj);
-    visit_type_uint32(v, name, &cpu->sve_max_vq, errp);
+    uint32_t value;
+
+    /* All vector lengths are disabled when SVE is off. */
+    if (!cpu_isar_feature(aa64_sve, cpu)) {
+        value = 0;
+    } else {
+        value = cpu->sve_max_vq;
+    }
+    visit_type_uint32(v, name, &value, errp);
 }
 
-static void cpu_max_set_sve_vq(Object *obj, Visitor *v, const char *name,
-                               void *opaque, Error **errp)
+static void cpu_max_set_sve_max_vq(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     ARMCPU *cpu = ARM_CPU(obj);
     Error *err = NULL;
@@ -279,6 +287,34 @@ static void cpu_max_set_sve_vq(Object *obj, Visitor *v, const char *name,
     error_propagate(errp, err);
 }
 
+static void cpu_arm_get_sve(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    ARMCPU *cpu = ARM_CPU(obj);
+    bool value = cpu_isar_feature(aa64_sve, cpu);
+
+    visit_type_bool(v, name, &value, errp);
+}
+
+static void cpu_arm_set_sve(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    ARMCPU *cpu = ARM_CPU(obj);
+    Error *err = NULL;
+    bool value;
+    uint64_t t;
+
+    visit_type_bool(v, name, &value, &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+
+    t = cpu->isar.id_aa64pfr0;
+    t = FIELD_DP64(t, ID_AA64PFR0, SVE, value);
+    cpu->isar.id_aa64pfr0 = t;
+}
+
 /* -cpu max: if KVM is enabled, like -cpu host (best possible with this host);
  * otherwise, a CPU with as many features enabled as our emulation supports.
  * The version of '-cpu max' for qemu-system-arm is defined in cpu.c;
@@ -391,8 +427,10 @@ static void aarch64_max_initfn(Object *obj)
 #endif
 
         cpu->sve_max_vq = ARM_MAX_VQ;
-        object_property_add(obj, "sve-max-vq", "uint32", cpu_max_get_sve_vq,
-                            cpu_max_set_sve_vq, NULL, NULL, &error_fatal);
+        object_property_add(obj, "sve-max-vq", "uint32", cpu_max_get_sve_max_vq,
+                            cpu_max_set_sve_max_vq, NULL, NULL, &error_fatal);
+        object_property_add(obj, "sve", "bool", cpu_arm_get_sve,
+                            cpu_arm_set_sve, NULL, NULL, &error_fatal);
     }
 }
 
diff --git a/target/arm/monitor.c b/target/arm/monitor.c
index 560970de7f5c..2209b27b9a08 100644
--- a/target/arm/monitor.c
+++ b/target/arm/monitor.c
@@ -97,7 +97,7 @@ GICCapabilityList *qmp_query_gic_capabilities(Error **errp)
  * then the order that considers those dependencies must be used.
  */
 static const char *cpu_model_advertised_features[] = {
-    "aarch64", "pmu",
+    "aarch64", "pmu", "sve",
     NULL
 };
 
diff --git a/tests/arm-cpu-features.c b/tests/arm-cpu-features.c
index 198ff6d6b495..202bc0e3e823 100644
--- a/tests/arm-cpu-features.c
+++ b/tests/arm-cpu-features.c
@@ -179,6 +179,7 @@ static void test_query_cpu_model_expansion(const void *data)
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
         assert_has_feature(qts, "max", "aarch64");
+        assert_has_feature(qts, "max", "sve");
         assert_has_feature(qts, "cortex-a57", "pmu");
         assert_has_feature(qts, "cortex-a57", "aarch64");
 
-- 
2.21.0