| From 06fea97f2d216af0c5cb34c617301f378f4b8031 Mon Sep 17 00:00:00 2001 |
| From: Josh Poimboeuf <jpoimboe@redhat.com> |
| Date: Fri, 12 Apr 2019 15:39:29 -0500 |
| Subject: [PATCH 24/30] x86/speculation: Support 'mitigations=' cmdline option |
| |
| 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 <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 |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| Documentation/admin-guide/kernel-parameters.txt | 16 +++++++++++----- |
| arch/x86/kernel/cpu/bugs.c | 11 +++++++++-- |
| arch/x86/mm/pti.c | 4 +++- |
| 3 files changed, 23 insertions(+), 8 deletions(-) |
| |
| diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt |
| index 6a1b94afb005..31c17532c219 100644 |
| --- a/Documentation/admin-guide/kernel-parameters.txt |
| +++ b/Documentation/admin-guide/kernel-parameters.txt |
| @@ -2503,15 +2503,20 @@ |
| 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 |
| @@ -2519,12 +2524,13 @@ |
| 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 |
| diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c |
| index 8d432a3d38a3..904d55cf80a2 100644 |
| --- a/arch/x86/kernel/cpu/bugs.c |
| +++ b/arch/x86/kernel/cpu/bugs.c |
| @@ -494,7 +494,8 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void) |
| 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)); |
| @@ -756,7 +757,8 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void) |
| 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", |
| @@ -1077,6 +1079,11 @@ static void __init l1tf_select_mitigation(void) |
| if (!boot_cpu_has_bug(X86_BUG_L1TF)) |
| return; |
| |
| + if (cpu_mitigations_off()) |
| + l1tf_mitigation = L1TF_MITIGATION_OFF; |
| + else if (cpu_mitigations_auto_nosmt()) |
| + l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT; |
| + |
| override_cache_bits(&boot_cpu_data); |
| |
| switch (l1tf_mitigation) { |
| diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c |
| index c1fc1ae6b429..4df3e5c89d57 100644 |
| --- a/arch/x86/mm/pti.c |
| +++ b/arch/x86/mm/pti.c |
| @@ -35,6 +35,7 @@ |
| #include <linux/spinlock.h> |
| #include <linux/mm.h> |
| #include <linux/uaccess.h> |
| +#include <linux/cpu.h> |
| |
| #include <asm/cpufeature.h> |
| #include <asm/hypervisor.h> |
| @@ -115,7 +116,8 @@ void __init pti_check_boottime_disable(void) |
| } |
| } |
| |
| - if (cmdline_find_option_bool(boot_command_line, "nopti")) { |
| + if (cmdline_find_option_bool(boot_command_line, "nopti") || |
| + cpu_mitigations_off()) { |
| pti_mode = PTI_FORCE_OFF; |
| pti_print_if_insecure("disabled on command line."); |
| return; |
| -- |
| 2.21.0 |
| |