pointer masking: Implement hstatus.HUPMM (Flush TLB on changing hstatus.HUPMM)

Author: YenHaoChen

riscv/csrs.cc

@@ -1859,8 +1859,15 @@ hstatus_csr_t::hstatus_csr_t(processor_t* const proc, const reg_t addr):
 bool hstatus_csr_t::unlogged_write(const reg_t val) noexcept {
   const reg_t mask = HSTATUS_VTSR | HSTATUS_VTW
     | (proc->supports_impl(IMPL_MMU) ? HSTATUS_VTVM : 0)
+    | (proc->extension_enabled(EXT_SSNPM) ? HSTATUS_HUPMM : 0)
     | HSTATUS_HU | HSTATUS_SPVP | HSTATUS_SPV | HSTATUS_GVA;
 
-  const reg_t new_hstatus = (read() & ~mask) | (val & mask);
+  const reg_t pmm_reserved = 1; // Reserved value of mseccfg.PMM
+  reg_t pmm = get_field(val, HSTATUS_HUPMM);
+  const reg_t adjusted_val = set_field(val, HSTATUS_HUPMM, pmm != pmm_reserved ? pmm : 0);
+
+  const reg_t new_hstatus = (read() & ~mask) | (adjusted_val & mask);
+  if (get_field(new_hstatus, HSTATUS_HUPMM) != get_field(read(), HSTATUS_HUPMM))
+    proc->get_mmu()->flush_tlb();
   return basic_csr_t::unlogged_write(new_hstatus);
 }

riscv/mmu.cc

@@ -624,8 +624,12 @@ reg_t mmu_t::get_pmlen(bool effective_virt, reg_t effective_priv, xlate_flags_t
     pmm = get_field(proc->state.menvcfg->read(), MENVCFG_PMM);
   else if (effective_virt && effective_priv == PRV_S)
     pmm = get_field(proc->state.henvcfg->read(), HENVCFG_PMM);
+  else if (proc->state.prv == PRV_U && flags.forced_virt)
+    pmm = get_field(proc->state.hstatus->read(), HSTATUS_HUPMM);
   else if (effective_priv == PRV_U)
     pmm = get_field(proc->state.senvcfg->read(), SENVCFG_PMM);
+  else
+    assert(false);
 
   switch (pmm) {
     case 2: return 7;