Message-ID: <20260130194753.672739-1-sohil.mehta@intel.com>
Date: Fri, 30 Jan 2026 11:47:53 -0800
From: Sohil Mehta <sohil.mehta@...el.com>
To: Dave Hansen <dave.hansen@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>,
	x86@...nel.org
Cc: Thomas Gleixner <tglx@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Nikolay Borisov <nik.borisov@...e.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Sohil Mehta <sohil.mehta@...el.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4] scripts/x86/intel: Add a script to update the old microcode list

The kernel maintains a table of minimum expected microcode revisions for
Intel CPUs in intel-ucode-defs.h. Systems with microcode older than
these revisions are flagged with X86_BUG_OLD_MICROCODE.

The static list of microcode revisions needs to be updated periodically
in response to releases of the official microcode at:
https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files.git.

Introduce a simple script to extract the revision information from the
microcode files and print it in the precise format expected by the
microcode header.

Maintaining the script in the kernel tree ensures a central location
that a submitter can use to generate the kernel-specific update. This
not only reduces the possibility of errors but also makes it easier to
validate the changes for reviewers and maintainers.

Typically, someone at Intel would see a new public release, wait for at
least three months to ensure the update is stable, run this script to
refresh the intel-ucode-defs.h file, and send a patch upstream to update
the mainline and stable versions.

Having a standard update script and a defined process minimizes the
ambiguity when refreshing the old microcode list. As always, there can
be exceptions to this process which should be supported with appropriate
justification.

Originally-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
---
v4:
 - Add suggested timeline to the update process.
 - Include platform ID information based on Dave's series:
   https://lore.kernel.org/all/20260119195047.86E3C696@davehans-spike.ostc.intel.com/
   This patch should be applied after the bug-fix series has merged.

v3: https://lore.kernel.org/lkml/20250825171510.3332029-1-sohil.mehta@intel.com/
 - Include motivation for having the script in the kernel. (Boris)
 - Update instructions to clarify typical usage. (Boris)
---
 MAINTAINERS                        |   1 +
 scripts/update-intel-ucode-defs.py | 128 +++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100755 scripts/update-intel-ucode-defs.py

diff --git a/MAINTAINERS b/MAINTAINERS
index 0d044a58cbfe..861c0c42c95d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -28245,6 +28245,7 @@ S:	Maintained
 F:	Documentation/admin-guide/hw-vuln/
 F:	arch/x86/include/asm/nospec-branch.h
 F:	arch/x86/kernel/cpu/bugs.c
+F:	scripts/update-intel-ucode-defs.py
 
 X86 MCE INFRASTRUCTURE
 M:	Tony Luck <tony.luck@...el.com>
diff --git a/scripts/update-intel-ucode-defs.py b/scripts/update-intel-ucode-defs.py
new file mode 100755
index 000000000000..50ec47cea1c5
--- /dev/null
+++ b/scripts/update-intel-ucode-defs.py
@@ -0,0 +1,128 @@
+#!/usr/bin/python3
+# SPDX-License-Identifier: GPL-2.0
+import argparse
+import re
+import shutil
+import subprocess
+import sys
+import os
+
+script = os.path.relpath(__file__)
+
+DESCRIPTION = f"""
+For Intel CPUs, update the microcode revisions that determine
+X86_BUG_OLD_MICROCODE.
+
+This script is intended to be run in response to releases of the
+official Intel microcode GitHub repository:
+https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files.git
+
+It takes the Intel microcode files as input and uses iucode-tool to
+extract the revision information. It prints the output in the format
+expected by intel-ucode-defs.h.
+
+Usage:
+    ./{script} /path/to/microcode/files > /path/to/intel-ucode-defs.h
+
+Typically, someone at Intel would see a new public release, wait for at
+least three months to ensure the update is stable, run this script to
+refresh the intel-ucode-defs.h file, and send a patch upstream to update
+the mainline and stable versions.
+
+As always, there can be exceptions to the above process which should be
+supported by appropriate justification.
+"""
+
+parser = argparse.ArgumentParser(description=DESCRIPTION,
+                                 formatter_class=argparse.RawDescriptionHelpFormatter)
+parser.add_argument('ucode_files', nargs='+', help='Path(s) to the microcode files')
+
+args = parser.parse_args()
+
+# Process the microcode files using iucode-tool
+if shutil.which("iucode-tool") is None:
+    print("Error: iucode-tool not found, please install it", file=sys.stderr)
+    sys.exit(1)
+
+cmd = ['iucode-tool', '--list-all' ]
+cmd.extend(args.ucode_files)
+
+process = subprocess.Popen(cmd, stdout=subprocess.PIPE, universal_newlines=True)
+process.wait()
+if process.returncode != 0:
+    print("Error: iucode-tool ran into an error, exiting", file=sys.stderr)
+    sys.exit(1)
+
+# Functions to extract family, model, and stepping
+def bits(val, bottom, top):
+    mask = (1 << (top + 1 - bottom)) - 1
+    mask = mask << bottom
+    return (val & mask) >> bottom
+
+def family(sig):
+    if bits(sig, 8, 11) == 0xf:
+        return bits(sig, 8, 11) + bits(sig, 20, 27)
+    return bits(sig, 8, 11)
+
+def model(sig):
+    return bits(sig, 4, 7)  | (bits(sig, 16, 19) << 4)
+
+def step(sig):
+    return bits(sig, 0, 3)
+
+# Parse the output of iucode-tool
+ucode_list = []
+for line in process.stdout:
+    if line.find(" sig ") == -1:
+        continue
+    sig = re.search('sig (0x[0-9a-fA-F]+)', line).group(1)
+    rev = re.search('rev (0x[0-9a-fA-F]+)', line).group(1)
+    pfm = re.search('pf_mask (0x[0-9a-fA-F]+)', line).group(1)
+    sig = int(sig, 16)
+    rev = int(rev, 16)
+    pfm = int(pfm, 16)
+    debug_rev = bits(rev, 31, 31)
+    if debug_rev != 0:
+        print("Error: Debug ucode file found, exiting", file=sys.stderr)
+        sys.exit(1)
+
+    ucrev = {}
+    ucrev['sig']       = sig
+    ucrev['platforms'] = pfm
+    ucrev['rev']       = rev
+    ucode_list.append(ucrev)
+
+# Remove duplicates, if any
+ucode_dict = {}
+for rev in ucode_list:
+    ucode_key = (rev['sig'], rev['platforms'])
+    existing = ucode_dict.get(ucode_key)
+    if existing is not None:
+        # If the existing one is newer, just move on:
+        if existing['rev'] > rev['rev']:
+            continue
+    ucode_dict[ucode_key] = rev
+
+# Prepare the microcode entries
+ucode_entries = []
+for ucode_key in ucode_dict:
+    rev = ucode_dict[ucode_key]
+    sig = rev['sig']
+    ucode_entries.append({
+        'family': family(sig),
+        'model': model(sig),
+        'steppings': 1 << step(sig),
+        'platforms': rev['platforms'],
+        'rev': rev['rev'],
+        'sig': sig
+    })
+
+if not ucode_entries:
+    print("Error: No valid microcode files found, exiting", file=sys.stderr)
+    sys.exit(1)
+
+# Sort and print the microcode entries
+ucode_entries.sort(key=lambda x: (x['family'], x['model'], x['steppings'], x['platforms']))
+for entry in ucode_entries:
+    print("{ .flags = X86_CPU_ID_FLAG_ENTRY_VALID, .vendor = X86_VENDOR_INTEL, .family = 0x%x,  .model = 0x%02x, .steppings = 0x%04x, .platform_mask = 0x%02x, .driver_data = 0x%x }," %
+          (entry['family'], entry['model'], entry['steppings'], entry['platforms'], entry['rev']))
-- 
2.43.0

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