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Jiri Kosina fc083988b6 x86/bugs, kvm: Introduce boot-time control of L1TF mitigations 
commit d90a7a0ec8 upstream

Introduce the 'l1tf=' kernel command line option to allow for boot-time
switching of mitigation that is used on processors affected by L1TF.

The possible values are:

  full
	Provides all available mitigations for the L1TF vulnerability. Disables
	SMT and enables all mitigations in the hypervisors. SMT control via
	/sys/devices/system/cpu/smt/control is still possible after boot.
	Hypervisors will issue a warning when the first VM is started in
	a potentially insecure configuration, i.e. SMT enabled or L1D flush
	disabled.

  full,force
	Same as 'full', but disables SMT control. Implies the 'nosmt=force'
	command line option. sysfs control of SMT and the hypervisor flush
	control is disabled.

  flush
	Leaves SMT enabled and enables the conditional hypervisor mitigation.
	Hypervisors will issue a warning when the first VM is started in a
	potentially insecure configuration, i.e. SMT enabled or L1D flush
	disabled.

  flush,nosmt
	Disables SMT and enables the conditional hypervisor mitigation. SMT
	control via /sys/devices/system/cpu/smt/control is still possible
	after boot. If SMT is reenabled or flushing disabled at runtime
	hypervisors will issue a warning.

  flush,nowarn
	Same as 'flush', but hypervisors will not warn when
	a VM is started in a potentially insecure configuration.

  off
	Disables hypervisor mitigations and doesn't emit any warnings.

Default is 'flush'.

Let KVM adhere to these semantics, which means:

  - 'lt1f=full,force'	: Performe L1D flushes. No runtime control
    			  possible.

  - 'l1tf=full'
  - 'l1tf-flush'
  - 'l1tf=flush,nosmt'	: Perform L1D flushes and warn on VM start if
			  SMT has been runtime enabled or L1D flushing
			  has been run-time enabled

  - 'l1tf=flush,nowarn'	: Perform L1D flushes and no warnings are emitted.

  - 'l1tf=off'		: L1D flushes are not performed and no warnings
			  are emitted.

KVM can always override the L1D flushing behavior using its 'vmentry_l1d_flush'
module parameter except when lt1f=full,force is set.

This makes KVM's private 'nosmt' option redundant, and as it is a bit
non-systematic anyway (this is something to control globally, not on
hypervisor level), remove that option.

Add the missing Documentation entry for the l1tf vulnerability sysfs file
while at it.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142323.202758176@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2018-08-15 18:12:56 +02:00
Documentation x86/bugs, kvm: Introduce boot-time control of L1TF mitigations 2018-08-15 18:12:56 +02:00
arch x86/bugs, kvm: Introduce boot-time control of L1TF mitigations 2018-08-15 18:12:56 +02:00
block block: reset bi_iter.bi_done after splitting bio 2018-08-03 07:50:42 +02:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto crypto: authenc - don't leak pointers to authenc keys 2018-08-03 07:50:40 +02:00
drivers x86/speculation/l1tf: Add sysfs reporting for l1tf 2018-08-15 18:12:50 +02:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs fix __legitimize_mnt()/mntput() race 2018-08-15 18:12:48 +02:00
include cpu/hotplug: Set CPU_SMT_NOT_SUPPORTED early 2018-08-15 18:12:56 +02:00
init init: rename and re-order boot_cpu_state_init() 2018-08-15 18:12:48 +02:00
ipc ipc/shm: fix shmat() nil address after round-down when remapping 2018-05-30 07:51:49 +02:00
kernel cpu/hotplug: Set CPU_SMT_NOT_SUPPORTED early 2018-08-15 18:12:56 +02:00
lib lib/rhashtable: consider param->min_size when setting initial table size 2018-07-25 11:25:09 +02:00
mm x86/speculation/l1tf: Limit swap file size to MAX_PA/2 2018-08-15 18:12:51 +02:00
net netlink: Don't shift on 64 for ngroups 2018-08-09 12:16:38 +02:00
samples samples/bpf: Partially fixes the bpf.o build 2018-04-26 11:02:12 +02:00
scripts Kbuild: fix # escaping in .cmd files for future Make 2018-07-11 16:29:21 +02:00
security ima: based on policy verify firmware signatures (pre-allocated buffer) 2018-08-03 07:50:31 +02:00
sound ASoC: topology: Add missing clock gating parameter when parsing hw_configs 2018-08-03 07:50:42 +02:00
tools selftests: intel_pstate: return Kselftest Skip code for skipped tests 2018-08-03 07:50:27 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM/Eventfd: Avoid crash when assign and deassign specific eventfd in parallel. 2018-07-25 11:25:07 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
…
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS dt-bindings: Document mti,mips-cpc binding 2018-03-15 10:54:35 +01:00
Makefile Linux 4.14.62 2018-08-09 12:16:40 +02:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.