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
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committed by
Thomas Gleixner

parent
98af845294
commit
d68be4c4d3
@@ -2514,15 +2514,20 @@
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http://repo.or.cz/w/linux-2.6/mini2440.git
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mitigations=
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Control optional mitigations for CPU vulnerabilities.
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This is a set of curated, arch-independent options, each
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of which is an aggregation of existing arch-specific
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options.
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[X86] Control optional mitigations for CPU
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vulnerabilities. This is a set of curated,
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arch-independent options, each of which is an
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aggregation of existing arch-specific options.
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off
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Disable all optional CPU mitigations. This
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improves system performance, but it may also
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expose users to several CPU vulnerabilities.
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Equivalent to: nopti [X86]
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nospectre_v2 [X86]
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spectre_v2_user=off [X86]
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spec_store_bypass_disable=off [X86]
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l1tf=off [X86]
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auto (default)
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Mitigate all CPU vulnerabilities, but leave SMT
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@@ -2530,12 +2535,13 @@
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users who don't want to be surprised by SMT
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getting disabled across kernel upgrades, or who
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have other ways of avoiding SMT-based attacks.
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This is the default behavior.
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Equivalent to: (default behavior)
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auto,nosmt
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Mitigate all CPU vulnerabilities, disabling SMT
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if needed. This is for users who always want to
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be fully mitigated, even if it means losing SMT.
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Equivalent to: l1tf=flush,nosmt [X86]
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mminit_loglevel=
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[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
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