arm: Clean up handling of no-MPU PMSA CPUs

ARM CPUs come in two flavours:
 * proper MMU ("VMSA")
 * only an MPU ("PMSA")
For PMSA, the MPU may be implemented, or not (in which case there
is default "always acts the same" behaviour, but it isn't guest
programmable).

QEMU is a bit confused about how we indicate this: we have an
ARM_FEATURE_MPU, but it's not clear whether this indicates
"PMSA, not VMSA" or "PMSA and MPU present" , and sometimes we
use it for one purpose and sometimes the other.

Currently trying to implement a PMSA-without-MPU core won't
work correctly because we turn off the ARM_FEATURE_MPU bit
and then a lot of things which should still exist get
turned off too.

As the first step in cleaning this up, rename the feature
bit to ARM_FEATURE_PMSA, which indicates a PMSA CPU (with
or without MPU).
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NAlistair Francis <alistair.francis@xilinx.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 1493122030-32191-5-git-send-email-peter.maydell@linaro.org

target/arm/cpu.c

@@ -593,7 +593,7 @@ static void arm_cpu_post_init(Object *obj)
                                  &error_abort);
     }
 
-    if (arm_feature(&cpu->env, ARM_FEATURE_MPU)) {
+    if (arm_feature(&cpu->env, ARM_FEATURE_PMSA)) {
         qdev_property_add_static(DEVICE(obj), &arm_cpu_has_mpu_property,
                                  &error_abort);
         if (arm_feature(&cpu->env, ARM_FEATURE_V7)) {
@@ -689,7 +689,7 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
 
     if (arm_feature(env, ARM_FEATURE_V7) &&
         !arm_feature(env, ARM_FEATURE_M) &&
-        !arm_feature(env, ARM_FEATURE_MPU)) {
+        !arm_feature(env, ARM_FEATURE_PMSA)) {
         /* v7VMSA drops support for the old ARMv5 tiny pages, so we
          * can use 4K pages.
          */
@@ -764,10 +764,10 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
     }
 
     if (!cpu->has_mpu) {
-        unset_feature(env, ARM_FEATURE_MPU);
+        unset_feature(env, ARM_FEATURE_PMSA);
     }
 
-    if (arm_feature(env, ARM_FEATURE_MPU) &&
+    if (arm_feature(env, ARM_FEATURE_PMSA) &&
         arm_feature(env, ARM_FEATURE_V7)) {
         uint32_t nr = cpu->pmsav7_dregion;
 
@@ -867,7 +867,7 @@ static void arm946_initfn(Object *obj)
 
     cpu->dtb_compatible = "arm,arm946";
     set_feature(&cpu->env, ARM_FEATURE_V5);
-    set_feature(&cpu->env, ARM_FEATURE_MPU);
+    set_feature(&cpu->env, ARM_FEATURE_PMSA);
     set_feature(&cpu->env, ARM_FEATURE_DUMMY_C15_REGS);
     cpu->midr = 0x41059461;
     cpu->ctr = 0x0f004006;
@@ -1079,7 +1079,7 @@ static void cortex_r5_initfn(Object *obj)
     set_feature(&cpu->env, ARM_FEATURE_THUMB_DIV);
     set_feature(&cpu->env, ARM_FEATURE_ARM_DIV);
     set_feature(&cpu->env, ARM_FEATURE_V7MP);
-    set_feature(&cpu->env, ARM_FEATURE_MPU);
+    set_feature(&cpu->env, ARM_FEATURE_PMSA);
     cpu->midr = 0x411fc153; /* r1p3 */
     cpu->id_pfr0 = 0x0131;
     cpu->id_pfr1 = 0x001;

target/arm/cpu.h

@@ -1181,7 +1181,7 @@ enum arm_features {
     ARM_FEATURE_V6K,
     ARM_FEATURE_V7,
     ARM_FEATURE_THUMB2,
-    ARM_FEATURE_MPU,    /* Only has Memory Protection Unit, not full MMU.  */
+    ARM_FEATURE_PMSA,   /* no MMU; may have Memory Protection Unit */
     ARM_FEATURE_VFP3,
     ARM_FEATURE_VFP_FP16,
     ARM_FEATURE_NEON,

target/arm/helper.c

@@ -485,7 +485,7 @@ static void contextidr_write(CPUARMState *env, const ARMCPRegInfo *ri,
 {
     ARMCPU *cpu = arm_env_get_cpu(env);
 
-    if (raw_read(env, ri) != value && !arm_feature(env, ARM_FEATURE_MPU)
+    if (raw_read(env, ri) != value && !arm_feature(env, ARM_FEATURE_PMSA)
         && !extended_addresses_enabled(env)) {
         /* For VMSA (when not using the LPAE long descriptor page table
          * format) this register includes the ASID, so do a TLB flush.
@@ -4615,7 +4615,7 @@ void register_cp_regs_for_features(ARMCPU *cpu)
         define_arm_cp_regs(cpu, v6k_cp_reginfo);
     }
     if (arm_feature(env, ARM_FEATURE_V7MP) &&
-        !arm_feature(env, ARM_FEATURE_MPU)) {
+        !arm_feature(env, ARM_FEATURE_PMSA)) {
         define_arm_cp_regs(cpu, v7mp_cp_reginfo);
     }
     if (arm_feature(env, ARM_FEATURE_V7)) {
@@ -4969,7 +4969,7 @@ void register_cp_regs_for_features(ARMCPU *cpu)
         }
     }
 
-    if (arm_feature(env, ARM_FEATURE_MPU)) {
+    if (arm_feature(env, ARM_FEATURE_PMSA)) {
         if (arm_feature(env, ARM_FEATURE_V6)) {
             /* PMSAv6 not implemented */
             assert(arm_feature(env, ARM_FEATURE_V7));
@@ -5131,7 +5131,7 @@ void register_cp_regs_for_features(ARMCPU *cpu)
             define_arm_cp_regs(cpu, id_pre_v8_midr_cp_reginfo);
         }
         define_arm_cp_regs(cpu, id_cp_reginfo);
-        if (!arm_feature(env, ARM_FEATURE_MPU)) {
+        if (!arm_feature(env, ARM_FEATURE_PMSA)) {
             define_one_arm_cp_reg(cpu, &id_tlbtr_reginfo);
         } else if (arm_feature(env, ARM_FEATURE_V7)) {
             define_one_arm_cp_reg(cpu, &id_mpuir_reginfo);
@@ -8442,7 +8442,7 @@ static bool get_phys_addr(CPUARMState *env, target_ulong address,
     /* pmsav7 has special handling for when MPU is disabled so call it before
      * the common MMU/MPU disabled check below.
      */
-    if (arm_feature(env, ARM_FEATURE_MPU) &&
+    if (arm_feature(env, ARM_FEATURE_PMSA) &&
         arm_feature(env, ARM_FEATURE_V7)) {
         *page_size = TARGET_PAGE_SIZE;
         return get_phys_addr_pmsav7(env, address, access_type, mmu_idx,
@@ -8457,7 +8457,7 @@ static bool get_phys_addr(CPUARMState *env, target_ulong address,
         return 0;
     }
 
-    if (arm_feature(env, ARM_FEATURE_MPU)) {
+    if (arm_feature(env, ARM_FEATURE_PMSA)) {
         /* Pre-v7 MPU */
         *page_size = TARGET_PAGE_SIZE;
         return get_phys_addr_pmsav5(env, address, access_type, mmu_idx,

target/arm/machine.c

@@ -142,7 +142,7 @@ static bool pmsav7_needed(void *opaque)
     ARMCPU *cpu = opaque;
     CPUARMState *env = &cpu->env;
 
-    return arm_feature(env, ARM_FEATURE_MPU) &&
+    return arm_feature(env, ARM_FEATURE_PMSA) &&
            arm_feature(env, ARM_FEATURE_V7);
 }