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Filename Latest commit message Latest commit date
Breno Leitao f3a324362b x86/bugs: Reset speculation control settings on init
[ Upstream commit 0125acda7d76b943ca55811df40ed6ec0ecf670f ]

Currently, x86_spec_ctrl_base is read at boot time and speculative bits
are set if Kconfig items are enabled. For example, IBRS is enabled if
CONFIG_CPU_IBRS_ENTRY is configured, etc. These MSR bits are not cleared
if the mitigations are disabled.

This is a problem when kexec-ing a kernel that has the mitigation
disabled from a kernel that has the mitigation enabled. In this case,
the MSR bits are not cleared during the new kernel boot. As a result,
this might have some performance degradation that is hard to pinpoint.

This problem does not happen if the machine is (hard) rebooted because
the bit will be cleared by default.

  [ bp: Massage. ]

Suggested-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20221128153148.1129350-1-leitao@debian.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-03-11 16:43:54 +01:00
arch x86/bugs: Reset speculation control settings on init 2023-03-11 16:43:54 +01:00
block blk-iocost: fix divide by 0 error in calc_lcoefs() 2023-03-11 16:43:54 +01:00
certs
crypto crypto: rsa-pkcs1pad - Use akcipher_request_complete 2023-03-11 16:43:41 +01:00
Documentation docs: Fix path paste-o for /sys/kernel/warn_count 2023-02-06 07:52:50 +01:00
drivers thermal: intel: Fix unsigned comparison with less than zero 2023-03-11 16:43:54 +01:00
fs udf: Define EFSCORRUPTED error code 2023-03-11 16:43:53 +01:00
include ASoC: soc-dapm.h: fixup warning struct snd_pcm_substream not declared 2023-03-11 16:43:48 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-08 11:22:59 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:23:06 +01:00
kernel timers: Prevent union confusion from unexpected restart_syscall() 2023-03-11 16:43:54 +01:00
lib lib/mpi: Fix buffer overrun when SG is too long 2023-03-11 16:43:38 +01:00
LICENSES
mm Revert "mm: Always release pages to the buddy allocator in memblock_free_late()." 2023-02-22 12:50:39 +01:00
net wifi: mac80211: make rate u32 in sta_set_rate_info_rx() 2023-03-11 16:43:42 +01:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2023-01-18 11:41:26 +01:00
scripts ftrace/scripts: Update the instructions for ftrace-bisect.sh 2023-02-06 07:52:44 +01:00
security tomoyo: fix broken dependency on *.conf.default 2023-02-06 07:52:35 +01:00
sound ASoC: soc-compress.c: fixup private_data on snd_soc_new_compress() 2023-03-11 16:43:46 +01:00
tools selftests/ftrace: Fix bash specific "==" operator 2023-03-11 16:43:50 +01:00
usr
virt KVM: arm64: vgic: Fix exit condition in scan_its_table() 2022-10-29 10:20:35 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS net/phy/mdio-i2c: Move header file to include/linux/mdio 2023-02-06 07:52:46 +01:00
Makefile Linux 5.4.234 2023-03-03 11:41:49 +01:00
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.