This is a note to let you know that I've just added the patch titled
[PATCH 21/27] x86/speculation: Support 'mitigations=' cmdline option
to the 5.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
0021-x86-speculation-Support-mitigations-cmdline-option.patch
and it can be found in the queue-5.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@vger.kernel.org> know about it.
>From bb42508b4ffd4daa964388437887fa4f1bfc4c43 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoim...@redhat.com>
Date: Fri, 12 Apr 2019 15:39:29 -0500
Subject: [PATCH 21/27] 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 <jpoim...@redhat.com>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Tested-by: Jiri Kosina <jkos...@suse.cz> (on x86)
Reviewed-by: Jiri Kosina <jkos...@suse.cz>
Cc: Borislav Petkov <b...@alien8.de>
Cc: "H . Peter Anvin" <h...@zytor.com>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Jiri Kosina <ji...@kernel.org>
Cc: Waiman Long <long...@redhat.com>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Cc: Jon Masters <j...@redhat.com>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky <schwidef...@de.ibm.com>
Cc: Heiko Carstens <heiko.carst...@de.ibm.com>
Cc: linux-s...@vger.kernel.org
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: linux-arm-ker...@lists.infradead.org
Cc: linux-a...@vger.kernel.org
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Tyler Hicks <tyhi...@canonical.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Randy Dunlap <rdun...@infradead.org>
Cc: Steven Price <steven.pr...@arm.com>
Cc: Phil Auld <pa...@redhat.com>
Link:
https://lkml.kernel.org/r/6616d0ae169308516cfdf5216bedd169f8a8291b.1555085500.git.jpoim...@redhat.com
Signed-off-by: Greg Kroah-Hartman <gre...@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 fcc4d1bc4526..4392a66bfa3d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2571,15 +2571,20 @@
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
@@ -2587,12 +2592,13 @@
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 ca354bc70c4e..5ec64b9976e6 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -506,7 +506,8 @@ 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));
@@ -771,7 +772,8 @@ 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",
@@ -1107,6 +1109,11 @@ 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 139b28a01ce4..d0255d64edce 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
Patches currently in stable-queue which might be from jpoim...@redhat.com are
queue-5.1/0019-x86-speculation-mds-Print-SMT-vulnerable-on-MSBDS-wi.patch
queue-5.1/0016-x86-speculation-Move-arch_smt_update-call-to-after-m.patch
queue-5.1/0024-x86-speculation-mds-Add-mitigations-support-for-MDS.patch
queue-5.1/0021-x86-speculation-Support-mitigations-cmdline-option.patch
queue-5.1/0022-powerpc-speculation-Support-mitigations-cmdline-opti.patch
queue-5.1/0020-cpu-speculation-Add-mitigations-cmdline-option.patch
queue-5.1/0023-s390-speculation-Support-mitigations-cmdline-option.patch
queue-5.1/0015-x86-speculation-mds-Add-mds-full-nosmt-cmdline-optio.patch
queue-5.1/0027-x86-speculation-mds-Fix-documentation-typo.patch
queue-5.1/0017-x86-speculation-mds-Add-SMT-warning-message.patch
queue-5.1/0018-x86-speculation-mds-Fix-comment.patch
