No description
  • C 98.2%
  • Assembly 1%
  • Makefile 0.3%
  • Shell 0.2%
  • Python 0.1%
Find a file
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Otavio Pontes 369428a646 x86/microcode: Check for offline CPUs before requesting new microcode
[ Upstream commit 7189b3c11903667808029ec9766a6e96de5012a5 ]

Currently, the late microcode loading mechanism checks whether any CPUs
are offlined, and, in such a case, aborts the load attempt.

However, this must be done before the kernel caches new microcode from
the filesystem. Otherwise, when offlined CPUs are onlined later, those
cores are going to be updated through the CPU hotplug notifier callback
with the new microcode, while CPUs previously onine will continue to run
with the older microcode.

For example:

Turn off one core (2 threads):

  echo 0 > /sys/devices/system/cpu/cpu3/online
  echo 0 > /sys/devices/system/cpu/cpu1/online

Install the ucode fails because a primary SMT thread is offline:

  cp intel-ucode/06-8e-09 /lib/firmware/intel-ucode/
  echo 1 > /sys/devices/system/cpu/microcode/reload
  bash: echo: write error: Invalid argument

Turn the core back on

  echo 1 > /sys/devices/system/cpu/cpu3/online
  echo 1 > /sys/devices/system/cpu/cpu1/online
  cat /proc/cpuinfo |grep microcode
  microcode : 0x30
  microcode : 0xde
  microcode : 0x30
  microcode : 0xde

The rationale for why the update is aborted when at least one primary
thread is offline is because even if that thread is soft-offlined
and idle, it will still have to participate in broadcasted MCE's
synchronization dance or enter SMM, and in both examples it will execute
instructions so it better have the same microcode revision as the other
cores.

 [ bp: Heavily edit and extend commit message with the reasoning behind all
   this. ]

Fixes: 30ec26da99 ("x86/microcode: Do not upload microcode if CPUs are offline")
Signed-off-by: Otavio Pontes <otavio.pontes@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Ashok Raj <ashok.raj@intel.com>
Link: https://lkml.kernel.org/r/20210319165515.9240-2-otavio.pontes@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-14 09:44:17 +02:00
arch x86/microcode: Check for offline CPUs before requesting new microcode 2021-05-14 09:44:17 +02:00
block block: only update parent bi_status when bio fail 2021-04-16 11:46:38 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-04 10:26:29 +01:00
crypto crypto: rng - fix crypto_rng_reset() refcounting when !CRYPTO_STATS 2021-05-11 14:04:15 +02:00
Documentation dt-bindings: net: ethernet-controller: fix typo in NVMEM 2021-04-14 08:24:18 +02:00
drivers spi: stm32: drop devres version of spi_register_master 2021-05-14 09:44:17 +02:00
fs ovl: fix missing revert_creds() on error path 2021-05-14 09:44:16 +02:00
include KVM: Stop looking for coalesced MMIO zones if the bus is destroyed 2021-05-14 09:44:15 +02:00
init init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM 2021-04-10 13:34:32 +02:00
ipc
kernel tracing: Restructure trace_clock_global() to never block 2021-05-11 14:04:18 +02:00
lib avoid __memcat_p link failure 2021-05-07 10:51:37 +02:00
LICENSES
mm mm: fix race by making init_zero_pfn() early_initcall 2021-04-07 14:47:42 +02:00
net cfg80211: scan: drop entry from hidden_list on overflow 2021-05-14 09:44:13 +02:00
samples samples, bpf: Add missing munmap in xdpsock 2021-03-17 17:03:33 +01:00
scripts ftrace: Have recordmcount use w8 to read relp->r_info in arm64_is_fake_mcount 2021-03-09 11:09:39 +01:00
security security: commoncap: fix -Wstringop-overread warning 2021-05-11 14:04:16 +02:00
sound ALSA: hda/realtek: ALC285 Thinkpad jack pin quirk is unreachable 2021-05-14 09:44:15 +02:00
tools perf ftrace: Fix access to pid in array when setting a pid filter 2021-05-07 10:51:37 +02:00
usr
virt KVM: Stop looking for coalesced MMIO zones if the bus is destroyed 2021-05-14 09:44:15 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.118 2021-05-11 14:04:18 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.