Add PBMTE bit to menvcfg and henvcfg mask values

Also make PBMTE set on reset for backward compatibility.

Since before Spike proceeded as if these bits were set if the extension was enabled.

riscv/processor.cc

@@ -380,14 +380,18 @@ void state_t::reset(processor_t* const proc, reg_t max_isa)
   csrmap[CSR_MVENDORID] = std::make_shared<const_csr_t>(proc, CSR_MVENDORID, 0);
   csrmap[CSR_MHARTID] = std::make_shared<const_csr_t>(proc, CSR_MHARTID, proc->get_id());
   const reg_t menvcfg_mask = (proc->extension_enabled(EXT_ZICBOM) ? MENVCFG_CBCFE | MENVCFG_CBIE : 0) |
-                             (proc->extension_enabled(EXT_ZICBOZ) ? MENVCFG_CBZE : 0);
-  csrmap[CSR_MENVCFG] = menvcfg = std::make_shared<masked_csr_t>(proc, CSR_MENVCFG, menvcfg_mask, 0);
+                             (proc->extension_enabled(EXT_ZICBOZ) ? MENVCFG_CBZE : 0) |
+                             (proc->extension_enabled(EXT_SVPBMT) ? MENVCFG_PBMTE : 0);
+  const reg_t menvcfg_init = (proc->extension_enabled(EXT_SVPBMT) ? MENVCFG_PBMTE : 0);
+  csrmap[CSR_MENVCFG] = menvcfg = std::make_shared<masked_csr_t>(proc, CSR_MENVCFG, menvcfg_mask, menvcfg_init);
   const reg_t senvcfg_mask = (proc->extension_enabled(EXT_ZICBOM) ? SENVCFG_CBCFE | SENVCFG_CBIE : 0) |
                              (proc->extension_enabled(EXT_ZICBOZ) ? SENVCFG_CBZE : 0);
   csrmap[CSR_SENVCFG] = senvcfg = std::make_shared<masked_csr_t>(proc, CSR_SENVCFG, senvcfg_mask, 0);
   const reg_t henvcfg_mask = (proc->extension_enabled(EXT_ZICBOM) ? HENVCFG_CBCFE | HENVCFG_CBIE : 0) |
-                             (proc->extension_enabled(EXT_ZICBOZ) ? HENVCFG_CBZE : 0);
-  csrmap[CSR_HENVCFG] = henvcfg = std::make_shared<henvcfg_csr_t>(proc, CSR_HENVCFG, henvcfg_mask, 0, menvcfg);
+                             (proc->extension_enabled(EXT_ZICBOZ) ? HENVCFG_CBZE : 0) |
+                             (proc->extension_enabled(EXT_SVPBMT) ? HENVCFG_PBMTE : 0);
+  const reg_t henvcfg_init = (proc->extension_enabled(EXT_SVPBMT) ? HENVCFG_PBMTE : 0);
+  csrmap[CSR_HENVCFG] = henvcfg = std::make_shared<henvcfg_csr_t>(proc, CSR_HENVCFG, henvcfg_mask, henvcfg_init, menvcfg);
 
   serialized = false;