From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.4 248/266] x86/speculation: Support mitigations= cmdline option Date: Wed, 15 May 2019 12:55:55 +0200 Message-ID: <20190515090731.402525457@linuxfoundation.org> References: <20190515090722.696531131@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190515090722.696531131@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josh Poimboeuf , Thomas Gleixner , Jiri Kosina , Borislav Petkov , "H . Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Jiri Kosina , Waiman Long , Andrea Arcangeli , Jon Masters , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Martin Schwidefsky , Heiko Carstens , linux-s390@vger.kernel.org, Catalin Marinas List-Id: linux-arch.vger.kernel.org From: Josh Poimboeuf commit d68be4c4d31295ff6ae34a8ddfaa4c1a8ff42812 upstream. 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 Signed-off-by: Thomas Gleixner Tested-by: Jiri Kosina (on x86) Reviewed-by: Jiri Kosina Cc: Borislav Petkov Cc: "H . Peter Anvin" Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Jiri Kosina Cc: Waiman Long Cc: Andrea Arcangeli Cc: Jon Masters Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: linux-s390@vger.kernel.org Cc: Catalin Marinas Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org Cc: Greg Kroah-Hartman Cc: Tyler Hicks Cc: Linus Torvalds Cc: Randy Dunlap Cc: Steven Price Cc: Phil Auld Link: https://lkml.kernel.org/r/6616d0ae169308516cfdf5216bedd169f8a8291b.1555085500.git.jpoimboe@redhat.com [bwh: Backported to 4.4: - Drop the auto,nosmt option and the l1tf mitigation selection, which we can't support - Adjust filenames, context] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- Documentation/kernel-parameters.txt | 14 +++++++++----- arch/x86/kernel/cpu/bugs.c | 6 ++++-- arch/x86/mm/kaiser.c | 4 +++- 3 files changed, 16 insertions(+), 8 deletions(-) --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2174,15 +2174,19 @@ bytes respectively. Such letter suffixes 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] auto (default) Mitigate all CPU vulnerabilities, but leave SMT @@ -2190,7 +2194,7 @@ bytes respectively. Such letter suffixes 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) mminit_loglevel= [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -479,7 +479,8 @@ static enum spectre_v2_mitigation_cmd __ char arg[20]; int ret, i; - if (cmdline_find_option_bool(boot_command_line, "nospectre_v2")) + if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") || + cpu_mitigations_off()) return SPECTRE_V2_CMD_NONE; ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg)); @@ -743,7 +744,8 @@ static enum ssb_mitigation_cmd __init ss char arg[20]; int ret, i; - if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable")) { + if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") || + cpu_mitigations_off()) { return SPEC_STORE_BYPASS_CMD_NONE; } else { ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable", --- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -10,6 +10,7 @@ #include #include #include +#include #undef pr_fmt #define pr_fmt(fmt) "Kernel/User page tables isolation: " fmt @@ -297,7 +298,8 @@ void __init kaiser_check_boottime_disabl goto skip; } - if (cmdline_find_option_bool(boot_command_line, "nopti")) + if (cmdline_find_option_bool(boot_command_line, "nopti") || + cpu_mitigations_off()) goto disable; skip: