From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- scripts/update-intel-ucode-defs.py | 130 +++++++++++++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) create mode 100755 scripts/update-intel-ucode-defs.py (limited to 'scripts/update-intel-ucode-defs.py') diff --git a/scripts/update-intel-ucode-defs.py b/scripts/update-intel-ucode-defs.py new file mode 100755 index 000000000..9d6cc2c60 --- /dev/null +++ b/scripts/update-intel-ucode-defs.py @@ -0,0 +1,130 @@ +#!/usr/bin/env 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. + +Any exception to this process should be supported with an appropriate +justification. +""" + +SIG_RE = re.compile(r'sig (0x[0-9a-fA-F]+)') +PFM_RE = re.compile(r'pf_mask (0x[0-9a-fA-F]+)') +REV_RE = re.compile(r'rev (0x[0-9a-fA-F]+)') + +# Functions to extract family, model, and stepping +def bits(val, bottom, top): + mask = (1 << (top + 1 - bottom)) - 1 + return (val >> bottom) & mask + +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) + +class Ucode: + def __init__(self, sig, pfm, rev): + self.family = family(sig) + self.model = model(sig) + self.steppings = 1 << step(sig) + self.platforms = pfm + self.rev = rev + + self.key = (self.family, self.model, self.steppings, self.platforms) + + def __eq__(self, other): + return self.key == other.key + + def __hash__(self): + return hash(self.key) + + def __str__(self): + return "{ .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 }," % \ + (self.family, self.model, self.steppings, self.platforms, self.rev) + +def main(): + 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 + iucode_tool = shutil.which("iucode-tool") or shutil.which("iucode_tool") + if iucode_tool is None: + print("Error: iucode-tool not found, please install it", file=sys.stderr) + sys.exit(1) + + cmd = [iucode_tool, '--list-all'] + args.ucode_files + + result = subprocess.run(cmd, capture_output=True, text=True) + if result.returncode != 0: + print("Error: iucode-tool ran into an error, exiting", file=sys.stderr) + if result.stderr: + print(result.stderr, file=sys.stderr, end='') + sys.exit(1) + + ucodes = set() + + # Parse the output of iucode-tool + for line in result.stdout.splitlines(): + sig_match = SIG_RE.search(line) + pfm_match = PFM_RE.search(line) + rev_match = REV_RE.search(line) + + if not (sig_match and pfm_match and rev_match): + continue + + sig = int(sig_match.group(1), 16) + pfm = int(pfm_match.group(1), 16) + rev = int(rev_match.group(1), 16) + debug_rev = bits(rev, 31, 31) + if debug_rev != 0: + print("Error: Debug ucode file found, exiting", file=sys.stderr) + sys.exit(1) + + ucodes.add(Ucode(sig, pfm, rev)) + + if not ucodes: + print("Error: No valid microcode files found, exiting", file=sys.stderr) + sys.exit(1) + + # Sort and print the microcode entries + print("/* SPDX-License-Identifier: GPL-2.0 */") + print("/* Auto-generated by scripts/update-intel-ucode-defs.py */") + for u in sorted(ucodes, key=lambda x: x.key): + print(u) + +if __name__ == "__main__": + main() -- cgit v1.3.1