Make misa.Q writable

riscv/csrs.cc

@@ -488,11 +488,12 @@ bool sstatus_csr_t::enabled(const reg_t which) {
 misa_csr_t::misa_csr_t(processor_t* const proc, const reg_t addr, const reg_t max_isa):
   basic_csr_t(proc, addr, max_isa),
   max_isa(max_isa),
-  write_mask(max_isa & (0  // allow MAFDCH bits in MISA to be modified
+  write_mask(max_isa & (0  // allow MAFDQCH bits in MISA to be modified
                         | (1L << ('M' - 'A'))
                         | (1L << ('A' - 'A'))
                         | (1L << ('F' - 'A'))
                         | (1L << ('D' - 'A'))
+                        | (1L << ('Q' - 'A'))
                         | (1L << ('C' - 'A'))
                         | (1L << ('H' - 'A'))
                         )
@@ -510,6 +511,7 @@ bool misa_csr_t::unlogged_write(const reg_t val) noexcept {
 
   reg_t adjusted_val = val;
   adjusted_val = dependency(adjusted_val, 'D', 'F');
+  adjusted_val = dependency(adjusted_val, 'Q', 'D');
 
   const reg_t old_misa = read();
   const bool prev_h = old_misa & (1L << ('H' - 'A'));