FEAT_NV defines three new bits in HCR_EL2: NV, NV1 and AT.  When the
feature is enabled, allow these bits to be written, and flush the
TLBs for the bits which affect page table interpretation.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
---
 target/arm/cpu-features.h | 5 +++++
 target/arm/helper.c       | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/target/arm/cpu-features.h b/target/arm/cpu-features.h
index 954d3582685..3a43c328d9e 100644
--- a/target/arm/cpu-features.h
+++ b/target/arm/cpu-features.h
@@ -839,6 +839,11 @@ static inline bool isar_feature_aa64_e0pd(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64mmfr2, ID_AA64MMFR2, E0PD) != 0;
 }
 
+static inline bool isar_feature_aa64_nv(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64mmfr2, ID_AA64MMFR2, NV) != 0;
+}
+
 static inline bool isar_feature_aa64_pmuv3p1(const ARMISARegisters *id)
 {
     return FIELD_EX64(id->id_aa64dfr0, ID_AA64DFR0, PMUVER) >= 4 &&
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 7889fd45d67..4e5fd25199c 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -5815,6 +5815,9 @@ static void do_hcr_write(CPUARMState *env, uint64_t value, uint64_t valid_mask)
         if (cpu_isar_feature(aa64_rme, cpu)) {
             valid_mask |= HCR_GPF;
         }
+        if (cpu_isar_feature(aa64_nv, cpu)) {
+            valid_mask |= HCR_NV | HCR_NV1 | HCR_AT;
+        }
     }
 
     if (cpu_isar_feature(any_evt, cpu)) {
@@ -5833,9 +5836,10 @@ static void do_hcr_write(CPUARMState *env, uint64_t value, uint64_t valid_mask)
      * HCR_DC disables stage1 and enables stage2 translation
      * HCR_DCT enables tagging on (disabled) stage1 translation
      * HCR_FWB changes the interpretation of stage2 descriptor bits
+     * HCR_NV and HCR_NV1 affect interpretation of descriptor bits
      */
     if ((env->cp15.hcr_el2 ^ value) &
-        (HCR_VM | HCR_PTW | HCR_DC | HCR_DCT | HCR_FWB)) {
+        (HCR_VM | HCR_PTW | HCR_DC | HCR_DCT | HCR_FWB | HCR_NV | HCR_NV1)) {
         tlb_flush(CPU(cpu));
     }
     env->cp15.hcr_el2 = value;
-- 
2.34.1