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Filename Latest commit message Latest commit date
Peter Zijlstra 3ee9e9a5af intel_idle: Disable IBRS during long idle
commit bf5835bcdb9635c97f85120dba9bfa21e111130f upstream.

Having IBRS enabled while the SMT sibling is idle unnecessarily slows
down the running sibling. OTOH, disabling IBRS around idle takes two
MSR writes, which will increase the idle latency.

Therefore, only disable IBRS around deeper idle states. Shallow idle
states are bounded by the tick in duration, since NOHZ is not allowed
for them by virtue of their short target residency.

Only do this for mwait-driven idle, since that keeps interrupts disabled
across idle, which makes disabling IBRS vs IRQ-entry a non-issue.

Note: C6 is a random threshold, most importantly C1 probably shouldn't
disable IBRS, benchmarking needed.

Suggested-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: no CPUIDLE_FLAG_IRQ_ENABLE]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[cascardo: context adjustments]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-10-07 09:16:55 +02:00
arch intel_idle: Disable IBRS during long idle 2022-10-07 09:16:55 +02:00
block blk-mq: don't create hctx debugfs dir until q->debugfs_dir is created 2022-08-25 11:17:36 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:11:22 +02:00
crypto crypto: drbg - make reseeding from get_random_bytes() synchronous 2022-06-22 14:11:18 +02:00
Documentation x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS 2022-10-07 09:16:55 +02:00
drivers intel_idle: Disable IBRS during long idle 2022-10-07 09:16:55 +02:00
fs ntfs: fix BUG_ON in ntfs_lookup_inode_by_name() 2022-10-05 10:37:42 +02:00
include x86/bugs: Report AMD retbleed vulnerability 2022-10-07 09:16:54 +02:00
init random: handle latent entropy and command line from random_init() 2022-06-22 14:11:17 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-14 18:11:41 +02:00
kernel workqueue: don't skip lockdep work dependency in cancel_work_sync() 2022-09-28 11:04:09 +02:00
lib lib/vdso: Mark do_hres() and do_coarse() as __always_inline 2022-09-05 10:27:47 +02:00
LICENSES
mm mm: fix madivse_pageout mishandling on non-LRU page 2022-10-05 10:37:43 +02:00
net net: sched: fix possible refcount leak in tc_new_tfilter() 2022-09-28 11:04:07 +02:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts mksysmap: Fix the mismatch of 'L0' symbols in System.map 2022-09-28 11:03:59 +02:00
security apparmor: Fix memleak in aa_simple_write_to_buffer() 2022-08-25 11:18:21 +02:00
sound ALSA: hda/realtek: Enable 4-speaker output Dell Precision 5530 laptop 2022-09-28 11:04:04 +02:00
tools Revert "x86/speculation: Add RSB VM Exit protections" 2022-10-07 09:16:54 +02:00
usr
virt KVM: Add infrastructure and macro to mark VM as bugged 2022-08-25 11:18:16 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
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MAINTAINERS MAINTAINERS: add Chandan as xfs maintainer for 5.4.y 2022-09-28 11:03:58 +02:00
Makefile Linux 5.4.216 2022-10-05 10:37:45 +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.