target/arm/cpu64: Ensure kvm really supports aarch64=off

If -cpu <cpu>,aarch64=off is used then KVM must also be used, and it
and the host must support running the vcpu in 32-bit mode. Also, if
-cpu <cpu>,aarch64=on is used, then it doesn't matter if kvm is
enabled or not.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index ee55237a9b..ab63115c77 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -426,13 +426,13 @@ static void aarch64_cpu_set_aarch64(Object *obj, bool value, Error **errp)
      * restriction allows us to avoid fixing up functionality that assumes a
      * uniform execution state like do_interrupt.
      */
-    if (!kvm_enabled()) {
-        error_setg(errp, "'aarch64' feature cannot be disabled "
-                         "unless KVM is enabled");
-        return;
-    }
-
     if (value == false) {
+        if (!kvm_enabled() || !kvm_arm_aarch32_supported(CPU(cpu))) {
+            error_setg(errp, "'aarch64' feature cannot be disabled "
+                             "unless KVM is enabled and 32-bit EL1 "
+                             "is supported");
+            return;
+        }
         unset_feature(&cpu->env, ARM_FEATURE_AARCH64);
     } else {
         set_feature(&cpu->env, ARM_FEATURE_AARCH64);