target/arm: Replace ARM_FEATURE_PXN with ID_MMFR0.VMSA check

The ARM_FEATURE_PXN bit indicates whether the CPU supports the PXN
bit in short-descriptor translation table format descriptors.  This
is indicated by ID_MMFR0.VMSA being at least 0b0100.  Replace the
feature bit with an ID register check, in line with our preference
for ID register checks over feature bits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200910173855.4068-2-peter.maydell@linaro.org

3 files changed, 17 insertions, 4 deletions

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index a7643deab4..d13a7b8717 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1588,7 +1588,6 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
     }
     if (arm_feature(env, ARM_FEATURE_LPAE)) {
         set_feature(env, ARM_FEATURE_V7MP);
-        set_feature(env, ARM_FEATURE_PXN);
     }
     if (arm_feature(env, ARM_FEATURE_CBAR_RO)) {
         set_feature(env, ARM_FEATURE_CBAR);
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 6036f61d60..14a673d8e9 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1772,6 +1772,15 @@ FIELD(ID_ISAR6, FHM, 8, 4)
 FIELD(ID_ISAR6, SB, 12, 4)
 FIELD(ID_ISAR6, SPECRES, 16, 4)
 
+FIELD(ID_MMFR0, VMSA, 0, 4)
+FIELD(ID_MMFR0, PMSA, 4, 4)
+FIELD(ID_MMFR0, OUTERSHR, 8, 4)
+FIELD(ID_MMFR0, SHARELVL, 12, 4)
+FIELD(ID_MMFR0, TCM, 16, 4)
+FIELD(ID_MMFR0, AUXREG, 20, 4)
+FIELD(ID_MMFR0, FCSE, 24, 4)
+FIELD(ID_MMFR0, INNERSHR, 28, 4)
+
 FIELD(ID_MMFR3, CMAINTVA, 0, 4)
 FIELD(ID_MMFR3, CMAINTSW, 4, 4)
 FIELD(ID_MMFR3, BPMAINT, 8, 4)
@@ -1949,7 +1958,6 @@ enum arm_features {
     ARM_FEATURE_CACHE_DIRTY_REG, /* 1136/1176 cache dirty status register */
     ARM_FEATURE_CACHE_BLOCK_OPS, /* v6 optional cache block operations */
     ARM_FEATURE_MPIDR, /* has cp15 MPIDR */
-    ARM_FEATURE_PXN, /* has Privileged Execute Never bit */
     ARM_FEATURE_LPAE, /* has Large Physical Address Extension */
     ARM_FEATURE_V8,
     ARM_FEATURE_AARCH64, /* supports 64 bit mode */
@@ -3615,6 +3623,11 @@ static inline bool isar_feature_aa32_vminmaxnm(const ARMISARegisters *id)
     return FIELD_EX32(id->mvfr2, MVFR2, FPMISC) >= 4;
 }
 
+static inline bool isar_feature_aa32_pxn(const ARMISARegisters *id)
+{
+    return FIELD_EX32(id->id_mmfr0, ID_MMFR0, VMSA) >= 4;
+}
+
 static inline bool isar_feature_aa32_pan(const ARMISARegisters *id)
 {
     return FIELD_EX32(id->id_mmfr3, ID_MMFR3, PAN) != 0;
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 88bd9dd35d..ab6ca23b64 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -10537,6 +10537,7 @@ static bool get_phys_addr_v6(CPUARMState *env, uint32_t address,
                              target_ulong *page_size, ARMMMUFaultInfo *fi)
 {
     CPUState *cs = env_cpu(env);
+    ARMCPU *cpu = env_archcpu(env);
     int level = 1;
     uint32_t table;
     uint32_t desc;
@@ -10563,7 +10564,7 @@ static bool get_phys_addr_v6(CPUARMState *env, uint32_t address,
         goto do_fault;
     }
     type = (desc & 3);
-    if (type == 0 || (type == 3 && !arm_feature(env, ARM_FEATURE_PXN))) {
+    if (type == 0 || (type == 3 && !cpu_isar_feature(aa32_pxn, cpu))) {
         /* Section translation fault, or attempt to use the encoding
          * which is Reserved on implementations without PXN.
          */
@@ -10605,7 +10606,7 @@ static bool get_phys_addr_v6(CPUARMState *env, uint32_t address,
         pxn = desc & 1;
         ns = extract32(desc, 19, 1);
     } else {
-        if (arm_feature(env, ARM_FEATURE_PXN)) {
+        if (cpu_isar_feature(aa32_pxn, cpu)) {
             pxn = (desc >> 2) & 1;
         }
         ns = extract32(desc, 3, 1);