arm: Add has-mpu property

For processors that support MPUs, add a property to de-feature it. This
is similar to the implementation of the EL3 feature.

The processor definition in init sets ARM_FEATURE_MPU if it can support
an MPU. post_init exposes the property, defaulting to true. If cleared
by the instantiator, ARM_FEATURE_MPU is then removed at realize time.

This is to support R profile processors that may or may-not have an MPU
configured.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 632918cc48786e868ea18aa6bd12f70597994cad.1434066412.git.peter.crosthwaite@xilinx.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 16 insertions, 0 deletions

diff --git a/target-arm/cpu-qom.h b/target-arm/cpu-qom.h
index 57b4a12069..072aa9baa7 100644
--- a/target-arm/cpu-qom.h
+++ b/target-arm/cpu-qom.h
@@ -103,6 +103,9 @@ typedef struct ARMCPU {
     /* CPU has security extension */
     bool has_el3;
 
+    /* CPU has memory protection unit */
+    bool has_mpu;
+
     /* PSCI conduit used to invoke PSCI methods
      * 0 - disabled, 1 - smc, 2 - hvc
      */
diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index 6fa51f4446..7496983b42 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -454,6 +454,9 @@ static Property arm_cpu_rvbar_property =
 static Property arm_cpu_has_el3_property =
             DEFINE_PROP_BOOL("has_el3", ARMCPU, has_el3, true);
 
+static Property arm_cpu_has_mpu_property =
+            DEFINE_PROP_BOOL("has-mpu", ARMCPU, has_mpu, true);
+
 static void arm_cpu_post_init(Object *obj)
 {
     ARMCPU *cpu = ARM_CPU(obj);
@@ -481,6 +484,12 @@ static void arm_cpu_post_init(Object *obj)
         qdev_property_add_static(DEVICE(obj), &arm_cpu_has_el3_property,
                                  &error_abort);
     }
+
+    if (arm_feature(&cpu->env, ARM_FEATURE_MPU)) {
+        qdev_property_add_static(DEVICE(obj), &arm_cpu_has_mpu_property,
+                                 &error_abort);
+    }
+
 }
 
 static void arm_cpu_finalizefn(Object *obj)
@@ -567,6 +576,10 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
         cpu->id_aa64pfr0 &= ~0xf000;
     }
 
+    if (!cpu->has_mpu) {
+        unset_feature(env, ARM_FEATURE_MPU);
+    }
+
     register_cp_regs_for_features(cpu);
     arm_cpu_register_gdb_regs_for_features(cpu);