This just allows read/write of three feature bits. ASID is still
ignored. Any writes to TTBR0_EL0 and TTBR1_EL0, including changing
the ASID, will still cause a complete flush of the TLB.

Signed-off-by: Jim MacArthur <jim.macarthur@linaro.org>
---
 target/arm/cpu-features.h | 7 +++++++
 target/arm/helper.c       | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/target/arm/cpu-features.h b/target/arm/cpu-features.h
index 579fa8f8f4..d56bda9ce0 100644
--- a/target/arm/cpu-features.h
+++ b/target/arm/cpu-features.h
@@ -346,6 +346,8 @@ FIELD(ID_AA64MMFR3, SDERR, 52, 4)
 FIELD(ID_AA64MMFR3, ADERR, 56, 4)
 FIELD(ID_AA64MMFR3, SPEC_FPACC, 60, 4)
 
+FIELD(ID_AA64MMFR4, ASID2, 8, 4)
+
 FIELD(ID_AA64DFR0, DEBUGVER, 0, 4)
 FIELD(ID_AA64DFR0, TRACEVER, 4, 4)
 FIELD(ID_AA64DFR0, PMUVER, 8, 4)
@@ -1369,6 +1371,11 @@ static inline bool isar_feature_aa64_aie(const ARMISARegisters *id)
     return FIELD_EX64_IDREG(id, ID_AA64MMFR3, AIE) != 0;
 }
 
+static inline bool isar_feature_aa64_asid2(const ARMISARegisters *id)
+{
+    return FIELD_EX64_IDREG(id, ID_AA64MMFR4, ASID2) != 0;
+}
+
 static inline bool isar_feature_aa64_mec(const ARMISARegisters *id)
 {
     return FIELD_EX64_IDREG(id, ID_AA64MMFR3, MEC) != 0;
diff --git a/target/arm/helper.c b/target/arm/helper.c
index c20334fa65..7812a82bab 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6102,6 +6102,9 @@ static void tcr2_el1_write(CPUARMState *env, const ARMCPRegInfo *ri,
     if (cpu_isar_feature(aa64_aie, cpu)) {
         valid_mask |= TCR2_AIE;
     }
+    if (cpu_isar_feature(aa64_asid2, cpu)) {
+        valid_mask |= TCR2_FNG1 | TCR2_FNG0 | TCR2_A2;
+    }
     value &= valid_mask;
     raw_write(env, ri, value);
 }
@@ -6121,6 +6124,9 @@ static void tcr2_el2_write(CPUARMState *env, const ARMCPRegInfo *ri,
     if (cpu_isar_feature(aa64_mec, cpu)) {
         valid_mask |= TCR2_AMEC0 | TCR2_AMEC1;
     }
+    if (cpu_isar_feature(aa64_asid2, cpu)) {
+        valid_mask |= TCR2_FNG1 | TCR2_FNG0 | TCR2_A2;
+    }
     value &= valid_mask;
     raw_write(env, ri, value);
 }
-- 
2.43.0