[PATCH 9/8] x86/virt/tdx: Add the global metadata code generation script

[Kai Huang <kai.huang@intel.com>]

From: Paolo Bonzini <pbonzini@redhat.com>

Currently, the global metadata reading code is auto-generated by a
script [1].  Future work to support KVM TDX will need to read more
fields thus will need to regenerate the metadata reading code.

Add the script to the kernel tree to keep it under track [2].

Note the script has some minor updates (to make it more readable)
comparing to [1] but they don't change the generated code.  Also change
the name to tdx_global_metadata.py to make it more specific.

Link: https://lore.kernel.org/0853b155ec9aac09c594caa60914ed6ea4dc0a71.camel@intel.com/ [1]
Link: https://lore.kernel.org/CABgObfZWjGc0FT2My_oEd6V8ZxYHD-RejndbU_FipuADgJkFbw@mail.gmail.com/ [2]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Co-developed-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
 MAINTAINERS                    |   1 +
 scripts/tdx_global_metadata.py | 187 +++++++++++++++++++++++++++++++++
 2 files changed, 188 insertions(+)
 create mode 100644 scripts/tdx_global_metadata.py

diff --git a/MAINTAINERS b/MAINTAINERS
index cf02cbf4bef1..fc983bc02109 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -24987,6 +24987,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/core
 F:	Documentation/arch/x86/
 F:	Documentation/devicetree/bindings/x86/
 F:	arch/x86/
+F:	scripts/tdx_global_metadata.py
 F:	tools/testing/selftests/x86
 
 X86 CPUID DATABASE
diff --git a/scripts/tdx_global_metadata.py b/scripts/tdx_global_metadata.py
new file mode 100644
index 000000000000..7f5cc13b1d78
--- /dev/null
+++ b/scripts/tdx_global_metadata.py
@@ -0,0 +1,187 @@
+#! /usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+import json
+import sys
+
+# Note: this script does not run as part of the build process.
+# It is used to generate structs from the TDX global_metadata.json
+# file, and functions to fill in said structs.  Rerun it if
+# you need more fields.
+
+TDX_STRUCTS = {
+    "version": [
+        "BUILD_DATE",
+        "BUILD_NUM",
+        "MINOR_VERSION",
+        "MAJOR_VERSION",
+        "UPDATE_VERSION",
+        "INTERNAL_VERSION",
+    ],
+    "features": [
+        "TDX_FEATURES0"
+    ],
+    "tdmr": [
+        "MAX_TDMRS",
+        "MAX_RESERVED_PER_TDMR",
+        "PAMT_4K_ENTRY_SIZE",
+        "PAMT_2M_ENTRY_SIZE",
+        "PAMT_1G_ENTRY_SIZE",
+    ],
+    "cmr": [
+        "NUM_CMRS", "CMR_BASE", "CMR_SIZE"
+    ],
+}
+
+STRUCT_PREFIX = "tdx_sys_info"
+FUNC_PREFIX = "get_tdx_sys_info"
+STRVAR_PREFIX = "sysinfo"
+
+def print_class_struct_field(field_name, element_bytes, num_fields, num_elements, file):
+    element_type = "u%s" % (element_bytes * 8)
+    element_array = ""
+    if num_fields > 1:
+        element_array += "[%d]" % (num_fields)
+    if num_elements > 1:
+        element_array += "[%d]" % (num_elements)
+    print("\t%s %s%s;" % (element_type, field_name, element_array), file=file)
+
+def print_class_struct(class_name, fields, file):
+    struct_name = "%s_%s" % (STRUCT_PREFIX, class_name)
+    print("struct %s {" % (struct_name), file=file)
+    for f in fields:
+        print_class_struct_field(
+            f["Field Name"].lower(),
+            int(f["Element Size (Bytes)"]),
+            int(f["Num Fields"]),
+            int(f["Num Elements"]),
+            file=file)
+    print("};", file=file)
+
+def print_read_field(field_id, struct_var, struct_member, indent, file):
+    print(
+        "%sif (!ret && !(ret = read_sys_metadata_field(%s, &val)))\n%s\t%s->%s = val;"
+        % (indent, field_id, indent, struct_var, struct_member),
+        file=file,
+    )
+
+def print_class_function(class_name, fields, file):
+    func_name = "%s_%s" % (FUNC_PREFIX, class_name)
+    struct_name = "%s_%s" % (STRUCT_PREFIX, class_name)
+    struct_var = "%s_%s" % (STRVAR_PREFIX, class_name)
+
+    print("static int %s(struct %s *%s)" % (func_name, struct_name, struct_var), file=file)
+    print("{", file=file)
+    print("\tint ret = 0;", file=file)
+    print("\tu64 val;", file=file)
+
+    has_i = 0
+    has_j = 0
+    for f in fields:
+        num_fields = int(f["Num Fields"])
+        num_elements = int(f["Num Elements"])
+        if num_fields > 1:
+            has_i = 1
+        if num_elements > 1:
+            has_j = 1
+
+    if has_i == 1 and has_j == 1:
+        print("\tint i, j;", file=file)
+    elif has_i == 1:
+        print("\tint i;", file=file)
+
+    print(file=file)
+    for f in fields:
+        fname = f["Field Name"]
+        field_id = f["Base FIELD_ID (Hex)"]
+        num_fields = int(f["Num Fields"])
+        num_elements = int(f["Num Elements"])
+        struct_member = fname.lower()
+        indent = "\t"
+        if num_fields > 1:
+            if fname == "CMR_BASE" or fname == "CMR_SIZE":
+                limit = "%s_%s->num_cmrs" %(STRVAR_PREFIX, "cmr")
+            elif fname == "CPUID_CONFIG_LEAVES" or fname == "CPUID_CONFIG_VALUES":
+                limit = "%s_%s->num_cpuid_config" %(STRVAR_PREFIX, "td_conf")
+            else:
+                limit = "%d" %(num_fields)
+            print("%sfor (i = 0; i < %s; i++)" % (indent, limit), file=file)
+            indent += "\t"
+            field_id += " + i"
+            struct_member += "[i]"
+        if num_elements > 1:
+            print("%sfor (j = 0; j < %d; j++)" % (indent, num_elements), file=file)
+            indent += "\t"
+            field_id += " * 2 + j"
+            struct_member += "[j]"
+
+        print_read_field(
+            field_id,
+            struct_var,
+            struct_member,
+            indent,
+            file=file,
+        )
+
+    print(file=file)
+    print("\treturn ret;", file=file)
+    print("}", file=file)
+
+def print_main_struct(file):
+    print("struct tdx_sys_info {", file=file)
+    for class_name, field_names in TDX_STRUCTS.items():
+        struct_name = "%s_%s" % (STRUCT_PREFIX, class_name)
+        struct_var = class_name
+        print("\tstruct %s %s;" % (struct_name, struct_var), file=file)
+    print("};", file=file)
+
+def print_main_function(file):
+    print("static int get_tdx_sys_info(struct tdx_sys_info *sysinfo)", file=file)
+    print("{", file=file)
+    print("\tint ret = 0;", file=file)
+    print(file=file)
+    for class_name, field_names in TDX_STRUCTS.items():
+        func_name = "%s_%s" % (FUNC_PREFIX, class_name)
+        struct_var = class_name
+        print("\tret = ret ?: %s(&sysinfo->%s);" % (func_name, struct_var), file=file)
+    print(file=file)
+    print("\treturn ret;", file=file)
+    print("}", file=file)
+
+jsonfile = sys.argv[1]
+hfile = sys.argv[2]
+cfile = sys.argv[3]
+hfileifdef = hfile.replace(".", "_")
+
+with open(jsonfile, "r") as f:
+    json_in = json.load(f)
+    fields = {x["Field Name"]: x for x in json_in["Fields"]}
+
+with open(hfile, "w") as f:
+    print("/* SPDX-License-Identifier: GPL-2.0 */", file=f)
+    print("/* Automatically generated TDX global metadata structures. */", file=f)
+    print("#ifndef _X86_VIRT_TDX_AUTO_GENERATED_" + hfileifdef.upper(), file=f)
+    print("#define _X86_VIRT_TDX_AUTO_GENERATED_" + hfileifdef.upper(), file=f)
+    print(file=f)
+    print("#include <linux/types.h>", file=f)
+    print(file=f)
+    for class_name, field_names in TDX_STRUCTS.items():
+        print_class_struct(class_name, [fields[x] for x in field_names], file=f)
+        print(file=f)
+    print_main_struct(file=f)
+    print(file=f)
+    print("#endif", file=f)
+
+with open(cfile, "w") as f:
+    print("// SPDX-License-Identifier: GPL-2.0", file=f)
+    print("/*", file=f)
+    print(" * Automatically generated functions to read TDX global metadata.", file=f)
+    print(" *", file=f)
+    print(" * This file doesn't compile on its own as it lacks of inclusion", file=f)
+    print(" * of SEAMCALL wrapper primitive which reads global metadata.", file=f)
+    print(" * Include this file to other C file instead.", file=f)
+    print(" */", file=f)
+    for class_name, field_names in TDX_STRUCTS.items():
+        print(file=f)
+        print_class_function(class_name, [fields[x] for x in field_names], file=f)
+    print(file=f)
+    print_main_function(file=f)
-- 
2.46.2