arm/kvm: add support for MTE

Extend the 'mte' property for the virt machine to cover KVM as
well. For KVM, we don't allocate tag memory, but instead enable the
capability.

If MTE has been enabled, we need to disable migration, as we do not
yet have a way to migrate the tags as well. Therefore, MTE will stay
off with KVM unless requested explicitly.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230428095533.21747-2-cohuck@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 5 insertions, 4 deletions

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 5182ed0c91..f6a88e52ac 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1480,6 +1480,7 @@ void arm_cpu_post_init(Object *obj)
                                      qdev_prop_allow_set_link_before_realize,
                                      OBJ_PROP_LINK_STRONG);
         }
+        cpu->has_mte = true;
     }
 #endif
 }
@@ -1616,7 +1617,7 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
         }
         if (cpu->tag_memory) {
             error_setg(errp,
-                       "Cannot enable %s when guest CPUs has MTE enabled",
+                       "Cannot enable %s when guest CPUs has tag memory enabled",
                        current_accel_name());
             return;
         }
@@ -1996,10 +1997,10 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
     }
 
 #ifndef CONFIG_USER_ONLY
-    if (cpu->tag_memory == NULL && cpu_isar_feature(aa64_mte, cpu)) {
+    if (!cpu->has_mte && cpu_isar_feature(aa64_mte, cpu)) {
         /*
-         * Disable the MTE feature bits if we do not have tag-memory
-         * provided by the machine.
+         * Disable the MTE feature bits if we do not have the feature
+         * setup by the machine.
          */
         cpu->isar.id_aa64pfr1 =
             FIELD_DP64(cpu->isar.id_aa64pfr1, ID_AA64PFR1, MTE, 0);