implement ADD_FEATURES similar to EXCLUDE_FEATURES

it allows to add any feature to selected pre-defined CPUID model

bochs/.bochsrc

@@ -145,6 +145,12 @@
 #  sapphire_rapids            Intel(R) Xeon(R) w9-3475X (Sappire Rapids)
 #  arrow_lake                 15th Gen Intel(R) Core(TM) Ultra 5 245K (ArrowLake)
 #
+#  ADD_FEATURES:
+#    Enable one of more CPU feature in the CPU configuration selected by MODEL.
+#    Could be useful for testing CPU with newer imaginary configurations by
+#    adding a specific feature or set of features to existing MODEL. The list 
+#    of features to add supplied through space or comma separated string.
+#
 #  EXCLUDE_FEATURES:
 #    Disable one of more CPU feature from CPU configuration selected by MODEL.
 #    Could be useful for testing CPU without a specific feature or set of

bochs/CHANGES

@@ -7,7 +7,7 @@ Brief summary :
  - Implemented AMX-TF32 ISA extension
  - Added initial support for AVX10_1 ISA extension and AVX10 CPUID leaf 0x24 (to be enabled in Xeon Granite Rapids)
  - CPUID: Added Arrow Lake CPU definition
- - CPUID: Support for disabling of one of more CPU feature from CPUID configuration (see "exclude_features" in bochsrc sample and documentation)
+ - CPUID: Support for enabling/disabling of one of more CPU features from CPUID configuration (see "add_features" and "exclude_features" in bochsrc sample and documentation)
  - Bugfixes for CPU emulation correctness (critical bugfixes for WAITPKG, LASS, XSAVEC/XSAVES, CPUID and SHA1 ISA implementation)
  - USB: Added the USB Debugger support for xHCI and UHCI
  - Added USB boot option (requires BIOS from https://github.com/fysnet/i440fx)
@@ -29,7 +29,7 @@ Detailed change log :
 - CPUID: 
   - Added Arrow Lake CPU definition
     - Features AVX-VNNI, AVX-IFMA, AVX-VNNI-INT8, AVX-VNNI-INT16, AVX_NE_CONVERT, GFNI, VAES/VPCLMULQDQ, SHA512, SM3/SM4, CMPCCXADD, LASS, SERIALIZE, UINTR
-  - Support for disabling of one of more CPU feature from CPUID configuration (see "exclude_features" in bochsrc sample and documentation)
+  - Support for enabling/disabling of one of more CPU features from CPUID configuration (see "add_features" and "exclude_features" in bochsrc sample and documentation)
 
 - Configure and compile
   - Fixed compilation of plugin version with debugger enabled on Windows

bochs/PARAM_TREE.txt

@@ -33,6 +33,7 @@ cpuid
   level
   family
   model
+  add_features
   exclude_features
   stepping
   vendor_string

bochs/config.cc

@@ -613,10 +613,17 @@ void bx_init_options()
       "Choose pre-defined CPU configuration",
       cpu_names, 0, 0);
 
+  new bx_param_string_c(cpu_param,
+      "add_features",
+      "Add these features to selected pre-defined CPU configuration",
+      "Choose features to add to selected pre-defined CPU configuration",
+      "",
+      BX_PATHNAME_LEN);
+
   new bx_param_string_c(cpu_param,
       "exclude_features",
-      "Exclude these features from CPU configuration",
+      "Exclude these features from selected pre-defined CPU configuration",
-      "Choose features to exclude from selected CPU configuration",
+      "Choose features to exclude from selected pre-defined CPU configuration",
       "",
       BX_PATHNAME_LEN);
 

bochs/cpu/cpu.h

@@ -1385,7 +1385,7 @@ public: // for now...
  ~BX_CPU_C();
 
   void initialize(void);
-  void exclude_cpuid_features(const char *feature_list);
+  void add_remove_cpuid_features(const char *feature_list, bool add);
   void init_statistics(void);
   void after_restore_state(void);
   void register_state(void);

bochs/cpu/init.cc

@@ -115,7 +115,7 @@ static bx_cpuid_t *cpuid_factory(BX_CPU_C *cpu)
 
 #include <string>
 
-void BX_CPU_C::exclude_cpuid_features(const char *input)
+void BX_CPU_C::add_remove_cpuid_features(const char *input, bool add)
 {
   // Use as delimiters: space, tab, newline, and comma
   static const char *delimiters = " \t\n,";
@@ -130,8 +130,12 @@ void BX_CPU_C::exclude_cpuid_features(const char *input)
       if (i > start) {
         std::string feature_name(input + start, input + i);
         int feature = match_cpu_feature(feature_name.c_str());
-        if (feature >= 0)
+        if (feature >= 0) {
-          BX_CPU_THIS_PTR cpuid->disable_cpu_extension(feature);
+          if (add)
+            BX_CPU_THIS_PTR cpuid->enable_cpu_extension(feature);
+          else
+            BX_CPU_THIS_PTR cpuid->disable_cpu_extension(feature);
+        }
         else
           BX_PANIC(("CPUID: unknown feature name \"%s\" cannot be disabled", feature_name.c_str()));
       }
@@ -161,7 +165,10 @@ void BX_CPU_C::initialize(void)
     BX_INFO(("initialized CPU model %s", cpu_model_name));
 
     const char* features_to_exclude = SIM->get_param_string(BXPN_CPU_EXCLUDE_FEATURES)->getptr();
-    exclude_cpuid_features(features_to_exclude);
+    add_remove_cpuid_features(features_to_exclude, false);
+
+    const char* features_to_eadd = SIM->get_param_string(BXPN_CPU_ADD_FEATURES)->getptr();
+    add_remove_cpuid_features(features_to_exclude, true);
   }
 
   BX_CPU_THIS_PTR cpuid->get_cpu_extensions(BX_CPU_THIS_PTR ia_extensions_bitmask);

bochs/doc/docbook/user/user.dbk

@@ -3411,6 +3411,13 @@ supported configurations. When this option is used and the value
 is different from 'bx_generic', the parameters of the <link linkend="bochsopt-cpuid">CPUID</link>
 option have no effect anymore. See the <xref linkend="cpu-models"> for supported values.
 </para>
+<para><command>add_features</command></para>
+<para>
+Enable one of more CPU feature in the CPU configuration selected by MODEL.
+Could be useful for testing CPU with newer imaginary configurations by
+adding a specific feature or set of features to existing MODEL. The list 
+of features to add supplied through space or comma separated string.
+</para>
 <para><command>exclude_features</command></para>
 <para>
 Disable one of more CPU feature from CPU configuration selected by MODEL.

bochs/doc/man/bochsrc.5

@@ -136,6 +136,13 @@ supported configurations. When this option is used and the value
 is different from 'bx_generic', the parameters of the CPUID option
 have no effect anymore. See the bochsrc sample for supported values.
 
+add_features:
+
+Enable one of more CPU feature in the CPU configuration selected by MODEL.
+Could be useful for testing CPU with newer imaginary configurations by
+adding a specific feature or set of features to existing MODEL. The list 
+of features to add supplied through space or comma separated string.
+
 exclude_features:
 
 Disable one of more CPU feature from CPU configuration selected by MODEL.

bochs/param_names.h

@@ -39,6 +39,7 @@
 #define BXPN_CPU_NCORES                  "cpu.n_cores"
 #define BXPN_CPU_NTHREADS                "cpu.n_threads"
 #define BXPN_CPU_MODEL                   "cpu.model"
+#define BXPN_CPU_ADD_FEATURES            "cpu.add_features"
 #define BXPN_CPU_EXCLUDE_FEATURES        "cpu.exclude_features"
 #define BXPN_IPS                         "cpu.ips"
 #define BXPN_SMP_QUANTUM                 "cpu.quantum"