x86/speculation: Support 'mitigations=' cmdline option

Configure x86 runtime CPU speculation bug mitigations in accordance with
the 'mitigations=' cmdline option.  This affects Meltdown, Spectre v2,
Speculative Store Bypass, and L1TF.

The default behavior is unchanged.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86)
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/6616d0ae169308516cfdf5216bedd169f8a8291b.1555085500.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf
2019-04-12 15:39:29 -05:00
committed by Thomas Gleixner
parent 98af845294
commit d68be4c4d3
3 changed files with 23 additions and 8 deletions

View File

@@ -2514,15 +2514,20 @@
http://repo.or.cz/w/linux-2.6/mini2440.git
mitigations=
Control optional mitigations for CPU vulnerabilities.
This is a set of curated, arch-independent options, each
of which is an aggregation of existing arch-specific
options.
[X86] Control optional mitigations for CPU
vulnerabilities. This is a set of curated,
arch-independent options, each of which is an
aggregation of existing arch-specific options.
off
Disable all optional CPU mitigations. This
improves system performance, but it may also
expose users to several CPU vulnerabilities.
Equivalent to: nopti [X86]
nospectre_v2 [X86]
spectre_v2_user=off [X86]
spec_store_bypass_disable=off [X86]
l1tf=off [X86]
auto (default)
Mitigate all CPU vulnerabilities, but leave SMT
@@ -2530,12 +2535,13 @@
users who don't want to be surprised by SMT
getting disabled across kernel upgrades, or who
have other ways of avoiding SMT-based attacks.
This is the default behavior.
Equivalent to: (default behavior)
auto,nosmt
Mitigate all CPU vulnerabilities, disabling SMT
if needed. This is for users who always want to
be fully mitigated, even if it means losing SMT.
Equivalent to: l1tf=flush,nosmt [X86]
mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this